News from Rohde & Schwarz · News from Rohde & Schwarz ... digital audio and video broadcasting as...

News from Rohde & Schwarz

Signals up to 3.3 GHzwith digital and analog modulation

ATC radiocommunicationsVHF-UHF multichannel radio equipment

Broadband communicationsDigital TV signals for cable headends

1541997/ II

2 News from Rohde & Schwarz Number 154 (1997/II)

Number 154 1997/II Volume 37

Signal Generator SMIQ features the classic mod-ulation modes AM, FM and ϕM plus I/Q, burst,pulse and broadband amplitude modulation upto 3.3 GHz. This makes SMIQ an unrivalled signal source for mobile radio, digital audio andvideo broadcasting as well as other broadbandsystems (page 4). Photo 42 814/1

Johann Klier Signal Generator SMIQHigh-quality digital modulation up to 3.3 GHz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Volker Janssen; Matthias Keller EMI Test Receiver ESCS30Top in full-compliance testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Hans-Günther Klarl Series 200 multichannel radio equipmentVHF-UHF ATC radiocommunications go multichannel . . . . . . . . . . . . . . . . . . . . . . . .10

Holger Buchholz; Hendrik Köhler HF Broadband System XB2900Custom-tailored shortwave communications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

Walter Bschor QAM Transmitter CT100QTProcessing digital TV signals for cable headends . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

Thomas Rieder; Michael Müller Paging Transmitters SU330/SD330New transmitters for nationwide coverage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

Dr. Klaus Rieskamp Satellite Tracking Antenna AS809Radiomonitoring LEO communication satellites. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

Thomas Mauksch CMD80: measurements for CDMA and AMPS mobiles . . . . . . . . . . . . . . . . . . . . . .22

Dr. Lothar Tschimpke Low-cost continuity check in board testing using Cocheck II . . . . . . . . . . . . . . . . . .24

Wolfgang Kufer Coherence analysis in audio technology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

Jörg Pfitzner; Long-term monitoring of sound-broadcast andWolf D. Seidl TV transmitters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27

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Application notes

For LGGA in Liechtenstein Rohde & Schwarz has set up a cable headend system with the main station in Vaduz and two remote receiving stations. The system is made up of components of CATV Headend System CT200 andsupplies the whole country with a great variety of sound and TV programs(page 34). Photo 42 828/1

3News from Rohde & Schwarz Number 154 (1997/II)

Published by ROHDE & SCHWARZ GmbH & Co. KG Mühldorfstraße 15 D -81671 MunichTelephone (0 89) 41 29-0 · international *(4989) 41 29-0 · Telex 523703 (rs d) · Editors: H. Wegener and G. Sönnichsen (German); G. Koranyi, C. B. Newberry (English) · Photos: S. Huber · Artwork: Nike Hofmann · Circulation 100 000 four times a year · ISSN 0028-9108 · Supply free of charge ·State company or position · Printed in the Federal Republic of Germany by peschke druck, Munich ·Reproduction of extracts permitted if source is stated and copy sent to R & S Munich

Imprint

Michael Fischbacher; Werner Rohde PC software for MPEG2 dream team DVG/DVMD .. . . . . . . . . . . . . . . . . . . . . . . . .29

Refresher topic

Software

Peter Hatzold Digital modulation and mobile radio (V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30

Panorama

Axel Stark Better HF radiocommunications for smaller vessels with Marine Dipole HX002M1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32

Dr. Olaf Ostwald New option for fast compression-point measurements with Vector Network Analyzer ZVR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33

Reinhard Scheide CATV Headend System CT200 supplies Liechtenstein with sound-broadcast programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

Rainer Ewert Repair System SMD-RS11 – a tool for state-of-the-art servicing of printed circuits . . . . . . . . . . . . . . . . . . . . . . . . . .35

Bernhard Wolf IMCOS – a message handling and control system for naval forces . . . . . . . . . . .36

Regular features

Reference: One wavelength ahead – Mikes Product Service GmbH . . . . . . . . . .17

Mathias Leutiger Test hint: Test signals with analog and digital modulation for vehicle information systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

Information in print . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37

Newsgrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38

Press comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40

Christian Rockrohr Final article: Swiss rail’s new radio measurement carriage: heading for the future . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41

Automatic measurements of RFI voltage, RFI power and RFI field strength according to CISPRand VDE are performed at a keystroke by EMITest Receiver ESCS30 from 9 kHz to 2.75 GHz;its main field of application: certification, precer-tification tests and development support (page 7).

Photo 42 781


SMIQ is a signal generator capable ofdigital and analog modulation for usein the development and production ofdigital mobile-radio receivers and com-ponents as well as for general-purposemeasurements (FIG 1). Its frequencyrange covers all common mobile-radiofrequencies and applications in the IFrange. The generator comes in fourmodels: SMIQ02, SMIQ03, SMIQ02Eand SMIQ03E. The figures 02 and 03

stand for the upper frequency limits of2.2 GHz and 3.3 GHz respectively. E signifies an economy model.

Models SMIQ02 and SMIQ03 featurehigh-quality I/Q modulation combinedwith extremely low phase noise. Thesynthesizer is of high spectral purity, en-suring excellent phase stability, whichfurther enhances vector modulationquality. High-grade vector modulationneed not be at the cost of economyhowever. This is convincingly demon-strated by the SMIQ economy models.They offer favourably priced, high-qual-ity instruments for entry to the field ofI/Q measurements.

All models feature the classic mod-ulation modes AM, FM and ϕM plusvector modulation (analog I/Q mod-ulation), burst, pulse and broadbandamplitude modulation. Among thesemodulation modes, vector modulationis of paramount importance. With abaseband width of 30 MHz, vectormodulation enables generation of complex modulation signals for the RFcarrier at bandwidths up to 60 MHz.This allows applications not only in mobile radio but also in the field of

DAB (digital audio broadcasting), DVB(digital video broadcasting) and forother broadband systems includingspread spectrum, eg CDMA (code-division multiple access).

Complete solutions for customer benefitSMIQ comes with a number of power-ful options for optimum adaptation tocustomer‘s requirements. This doesaway with the need for extra measuringequipment and the development of customized solutions. The advantage is obvious: time and cost are minimizedif complete systems with calibrated test signals can be readily supplied tothe user. Available options include amodulation coder and a data genera-tor for all models, and additionally afading simulator for models SMIQ02and SMIQ03.

The modulation coder supplies filteredbaseband signals for driving the I/Qmodulator. Digital modulation formats4FSK, GFSK, GMSK, BPSK, 8PSK,QPSK, OQPSK, π/4 DQPSK and 16QAM through 256QAM can be selected with clock rates up to 7.5 Msymbol/s. The data generatorsupplies the corresponding data se-quences and control signals for gener-ating the frame structure required formobile-radio networks. The range ofoptions is completed by a fading simu-lator. Fitted with this, SMIQ generatesfaded test signals in line with specifi-cations with a calibrated level at a keystroke, as it were, which is a trulyunique feature. Anyone who has set up a customized test system made up ofindividual instruments knows the effortinvolved and will appreciate this all-in-one solution.

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Signal Generator SMIQ

High-quality digital modulation up to 3.3 GHzVector Signal Generator SMIQ represents a new generation of signal generatorsfrom Rohde & Schwarz with digital modulation capability. SMIQ also featuresprecise I/Q modulation for broadband communication applications, short mea-surement times through fast synthesis and a large dynamic range thanks to itshigh spectral purity. Plus SMIQ comes with a real innovation: its fading simulator option allows predefined 6- or 12-path fading.

FIG 2Block diagram

of I/Q modulator ofSMIQ as well as

I and Q input signalsand I/Q diagram

for QPSK modulation

FIG 1 Signal Generator SMIQ, universal RFsource for research, development and productionin digital mobile radio Photo 42 814/2

I

Q

90°

I input

Q input

Out-put

Vector diagramI path

Q path

LO

I/Q modulatorInput signals

I

Q


I/Q modulation

Digital modulation techniques use fil-tered phase and/or amplitude shift keying. These complex forms of mod-ulation can be generated by an I/Qmodulator with high precision. The latter, also known as a quadrature mod-ulator, modulates orthogonal I and Q(in-phase and quadrature phase) com-ponents on an RF signal (FIG 2). AnLO (local oscillator) supplies a signal tothe mixer of the I path and, via a 90°phase shifter, also to the mixer of the Qpath. The two mixers effect amplitudemodulation of the 0° and 90° compo-nents of the RF signal. With appropri-ate signals applied to the IF inputs ofthe mixers (I and Q inputs), the I and Qcomponents can be modulated as re-quired. The two components are addedto form an output signal that can bemodulated in amplitude and phase as required. The example in FIG 2shows the characteristic of a carriervector in an I/Q diagram for QPSKmodulation with the corresponding I and Q input signals.

A basic requirement for low error vectorin digital modulation is a highly accu-rate I/Q modulator. So particular im-portance was attached to this feature indeveloping SMIQ. But there are otherrequirements. Spectral purity of thesynthesizer is of equal importance asphase errors also affect the error vector.How this has been implemented is demonstrated impressively by modelsSMIQ02 and SMIQ03. Economy mod-els SMIQ02E and SMIQ03E also offerextraordinarily high vector accuracy.The rms value of the error vector ofSMIQ is 0.3%, that of the economymodels 1%. FIG 3 shows as an example the error vector of SMIQ03 for the duration of a burst for NADC (North American digital cellular).

Another important criterion for the quality of an I/Q modulator is inter-modulation. Besides synthesizer phasenoise, it is intermodulation that deter-mines adjacent-channel power in digi-tal modulation. The high linearity of the

I/Q modulator in conjunction with thehigh spectral purity of models SMIQ02and SMIQ03 yields accuracy that evenmeets the stringent requirements for adjacent-channel selectivity measure-ments in the first adjacent channel forTETRA (trans-European trunked radio).FIG 4 demonstrates the spectral purityof a TETRA signal generated bySMIQ03. The measurement reveals adjacent-channel power of –71dBc at a spacing of 25 kHz for externallyapplied I/Q signals.

The I/Q modulator is also ideal for am-plitude modulation incidentally. Apartfrom large modulation bandwidth, itfeatures extremely small incidental ϕMwith AM. These characteristics can beutilized in a very convenient way bymeans of the broadband AM setup menu implemented in SMIQ.

Digital modulation

The modulation coder option of SMIQallows simple generation of digitalmodulation signals from digital inputsignals. By means of the built-in map-ping function (which allocates the statesin the I/Q diagram to the symbols) andadjustable digital filters, the input signals are converted into analog I andQ voltages driving the I/Q modulator.Selectable modulation formats, base-band filters and symbol rates areshown in the blue box. Apart from thestandard settings shown below, user-de-fined values for the mapping and base-band filters can be loaded into SMIQ.This is particularly useful if new standards are created that deviate frompreviously used formats and filters. Ex-ternal baseband signal processing thusbecomes superfluous in most cases.

The input interface was designed forhigh versatility of SMIQ. The modula-tion coder accepts digital input signalsboth in the form of serial bit-clocked bitstreams and as up to 8-bit-wide symbol-clocked parallel data. The inputs canbe configured as CMOS, TTL and ECLinterfaces and terminated with 1 kΩ or50 Ω. But SMIQ is not only capable ofmodulating external signals. The datagenerator option allows convenient,internal generation of user-defined data sequences and loading of storedsequences.

Articles

FIG 4 Spectrum of TETRA signal generated bySMIQ

FIG 3 Error vector over burst in NADC

Modulation format Baseband filter Symbol rate

4FSK √cos (α = 0.15 to 0.7), 1 kHz to 2.5 MHzcos (α = 0.15 to 0.7) Bessel Filter

GFSK, GMSK Gaussian B·T = 0.2 to 1 1 kHz to 2.5 MHz

BPSK, QPSK, OQPSK, √cos (α = 0.15 to 0.7), 1 kHz to 7.5 MHzπ/4 DQPSK, 8PSK cos (α = 0.15 to 0.7)

16, 32, 64, 256QAM √cos (α = 0.15 to 0.7), 1 kHz to 7.5 MHzcos (α = 0.15 to 0.7)


Standard settings at a keystroke

The advantages of ready programmedframe and data structures for standardmeasurements are known to everyonewho ever programmed data bit by bitfor BER measurements on receivers.What makes this so difficult is not onlythe tiresome programming of test equip-ment bit by bit but also the fact that this task requires detailed knowledge ofnetwork data structure. These difficul-ties are a thing of the past. With its datagenerator option, SMIQ offers a choiceof standard settings for various net-works (presently PHS, CDMA IS95,NADC, PDC) at a keystroke. Operation

TDMA time slot must have a specialcharacteristic so that other mobile-radiosubscribers are not disturbed. On theone hand the edge must not be too slowto avoid interference with adjacent timeslots, on the other hand the edge mustnot be too fast to avoid interferencefrom the generated spectral componentson adjacent frequency channels. SMIQ,fitted with data generator and mod-ulation coder, generates as standard apower ramp characteristic that meetsthe requirements both in the time andfrequency domain.

CDMA (code-division multiple access)systems, in contrast to TDMA systems,transmit several channels at the sametime and at the same frequency, sepa-rated by codes. This places high de-mands on the amplifiers used. Summa-tion of the CDMA channels yields anoutput signal with a high crest factor.The latter is the ratio of the peak valueto the rms value of the signal. The am-plifiers, therefore, must be highly linearas nonlinear distortion would give riseto intermodulation products in the adja-cent frequency channel. To check lin-earity, SMIQ offers a convenient functionallowing up to 18 code channels to beset in line with IS95. The levels can be

set separately for the pilot, sync andpaging channels and jointly for the remaining traffic channels.

The all-important speed factor

SMIQ was developed with a specialview to the current trend towards highmeasurement speed. Apart from fastfrequency setting, which has alwaysbeen a strong point of Rohde &Schwarz signal generators, SMIQ nowalso features fast level control. This is ofadvantage not only in the measurementof adjacent time-slot suppression withlevels of up to 50 dB being switchedbetween neighbouring slots, but also inRSSI (receiver signal strength indicator)calibration of receivers. During cali-bration, calculated level settings arecalled up one by one in the list mode,the setting time in this mode beingsmaller than 500 µs.

Whether standard or special-purposemeasurement, the user will benefit fromSMIQ in a variety of ways. Great oper-ating ease, preprogrammed standardsettings, high signal quality, short mea-surement times – all these features willhelp the user get the job done fast.

Johann Klier

Articles

Condensed data of Signal Generator SMIQFrequency range

SMIQ02 / SMIQ02E 300 kHz to 2.2 GHzSMIQ03 / SMIQ03E 300 kHz to 3.3 GHz

Frequency setting timeSMIQ02 / SMIQ03 <15 ms (<500 µs in list mode)SMIQ02E / SMIQ03E <25 ms

Spurious(carrier offset 10 kHz to 300 MHz) <–70 dBc

SSB phase noise (f = 1 GHz, carrier offset 20 kHz)SMIQ02 / SMIQ03 <–123 dBcSMIQ02E / SMIQ03E <–113 dBc

Level range –144 to 13 dBm

Analog modulation AM, FM, ϕM, BB-AM,vector, burst, pulse modulation

Digital modulation 4FSK, GFSK, GMSK, BPSK, 8PSK,QPSK, OQPSK, π/4 DQPSK, 16, 32, 64, 256QAM

Reader service card 154/01

is extremely easy and requires no net-work-specific knowledge. Operatorconvenience is enhanced by a largehigh-contrast LCD and menu control allowing setups to be loaded and bothdata and frame structure to be graphi-cally displayed. In addition, the datagenerator allows data sequences to be inserted into the data blocks ofTDMA (time-division multiple access)slots so that they are continued withoutinterruption in the next frame, as illustrated by FIG 5. This characteristicis needed, for example, in BER (bit error rate) measurements to evaluate receiver sensitivity. For such measure-ments a continuous PRBS (pseudo-random bit sequence) data stream mustbe sent in the data blocks.

To generate the correct signals forTDMA, which is frequently used in digital modulation, a further type ofmodulation, ie envelope modulation, isrequired to generate the power bursts.On/off switching of the RF power in a

FIG 5 SMIQ allows continuous data sequen-ces without any losses to be inserted into datablocks of time slots.

IT 1 IT 2 IT 3 IT 4 IT1 IT 2 IT 3 IT 4

PRBS

Frame


Even in its basic version EMI Test Re-ceiver ESCS30 – an important ex-tension to the worldwide successfulESHS/ESVS/ESS family [1] – is a full-compliance test receiver to CISPR andVDE. It performs EMC measurements tostandards with outstanding precision,immunity to overload, dynamic rangeand selection (FIG 1). The built-in timedomain analysis allows examination ofinterference versus time. When used for precertification testing of electricalequipment at the development stage,

ESCS30 detects critical frequenciesand serves for product optimization [2].This reduces development and manu-facturing costs, increases price calcula-tion reliability and makes for a success-ful product.

Automatic testsat a keystrokeAt a single keystroke ESCS30 performscomplete RFI voltage, RFI power andRFI field-strength measurements. Itdetermines the critical ranges of thespectrum by a prescan measurementusing the peak detector. The Max. Holdfunction allows intermittent interferenceto be detected. Data-reduction routinesserve for determining the frequencies

for the final measurement, which is then carried out by means of the quasi-peak and/or average detectorwith standard-conforming measurementtime. This concept saves valuable timethat would otherwise be wasted on examining frequency ranges with lowemission levels.

The test receiver automatically selectsthe correct CISPR bandwidth for thespecific test frequency and makes comparisons with limit lines, eg to ENstandard. In case of RFI voltage mea-surement the phase settings of the line-impedance stabilization network (LISN)are automatically set. The phase withthe highest RFI level is used for finalmeasurement and recorded. For RFIpower measurement ESCS30 inter-actively searches for the interferencemaxima. For RFI field-strength measure-ment the highest emissions are also determined interactively and recorded.

Simple test assemblies forall types of analysisTo perform measurements to EN stan-dards the following basic equipment isrequired:RFI voltage measurementEMI Test Receiver ESCS30, LISN (2-lineor 4-line V network), printer/plotterRFI power measurementEMI Test Receiver ESCS30, absorbingclamp (if necessary, slideway for auto-matic guidance of clamp), printer/plot-terRFI field-strength measurementEMI Test Receiver ESCS30, antennas(magnetic/electrical/electromagnetic),tripod/mast for fixing the antenna,printer/plotter (FIG 2)

RF analysis can be operated in theSpectrum Overview, Scan and Chan-nel Scan modes.

In the Spectrum Overview mode a fastmeasurement is made of the spectrumbetween start and stop frequency ac-cording to a user-selectable scan table.The minimum measurement time is 50 µs per result and the RF attenuation is

Articles

EMI Test Receiver ESCS30

Top infull-compliance testingThe highlights of EMI Test Receiver ESCS30: frequency range from 9 kHz throughto 2.75 GHz in one compact, favourably-priced instrument, complete with VGA colour display and macros for automatic testing, which makes an externalprocess controller mostly superfluous.

FIG 1 EMI Test Receiver ESCS30 (9 kHz to2.75 GHz) is a high-end EMC measurement instrument for certification, precertification anddevelopment. Photo 42 783


preselected. The step size of frequencyswitching is coupled to the selected IF bandwidth and ensures continuousmonitoring of the frequency range. Thetracking preselection remains active inthe Spectrum Overview mode and ensures the necessary immunity to over-load. This type of overview measure-ment can be switched to continuousscan for qualitative assessment of thespectrum.

In the Scan mode a standard-conform-ing measurement is again carried outon the basis of a user-selected scan table. The measurement, however, usesselectable step widths in a linear or logarithmic frequency raster. The switch-able autoranging function increases thedynamic range and prevents measure-ment errors that can be caused by over-load of the different receiver stages. Toreduce the measurement time, peakand average value can be measured simultaneously and displayed as sepa-rate traces. CISPR ranges A, B, C andD are predefined as scan ranges andcan be activated at a keystroke.

The Channel Scan mode is used ifmeasurements have to be made timeand again on the same frequencies asis the case with ready tested DUTswhere a scan would not yield any newresults. The Channel Scan comprises a list of up to 400 different frequenciesat which the level is measured using the selected receiver settings such asmeasurement time, bandwidth and detector.

The time domain analysis of ESCS30allows the time behaviour of interfer-

ence to be determined. It is also veryexpedient for correct setting of receivermeasurement time for RF analysis. Theuser can determine whether narrow-band interference fluctuates and the degree of fluctuation, and whether it isamplitude-modulated. Furthermore thepulse rate of broadband interferencecan be measured. The measurementtime is correct if it is greater than orequal to the reciprocal value of thepulse rate. Devices with thermostatic or microprocessor control generate discontinuous interference. ThereforeCISPR14 and EN55014 specify limitvalues for the RFI voltage with click-rate weighting in the range 0.15 to 30 MHz. Click interference frequentlyoccurs only at long time intervals. In the course of time domain analysis with a peak detector ESCS30 allowsthe signal to be measured with quasi-peak and average detector. Togetherwith the internal trigger that starts themeasurement only when a selectablethreshold is exceeded, this combinationaffords time-saving automatic measure-ment with clear result display (FIG 3).The time domain analysis with resolu-tion of 100 µs meets the accuracy re-quirements for pulse-duration measure-ments. Up to 30,000 results can bestored and zoomed with the markerfunction for detailed investigation.

An important tool for identifying signalsin the receive frequency range is IFspectrum analysis with realtime dis-play. A display range between 10 kHzand 10 MHz is selected for the chosenreceive frequency and the signal is assessed using a resolution bandwidthof 1, 3 or 10 kHz. The strength of

IF analysis is in the fast determination of interference signals.

Characteristics and operation

The outstanding features of ESCS30are:• measurement uncertainty <1 dB

(typ. <0.5 dB),• ten integrated preselectors,• selectable preamplifier 10 dB,• CISPR bandwidths 200 Hz, 9 kHz,

120 kHz, 1 MHz,• detectors (peak, average, quasi-

peak) with parallel output of resultsand bargraph display on colourmonitor,

• direct selection of CISPR measure-ment ranges with bandwidth, stepwidth and measurement time,

• automatic scan of frequency rangesand lists with up to 400 different frequencies,

• automatic level calibration and built-in selftest function,

• macros for RFI voltage, RFI powerand RFI field-strength measurements,

• nonvolatile storage of complete in-strument setups as well as limit linesand frequency-dependent correctionfactors of antennas and accessories,

• storage of results, limit and correc-tion values on built-in 3.5“ diskdrive,

• time domain analysis with displayrange from 5 ms to 1 h, manualtrigger (internal and external), user-selectable zooming of up to 30,000measured values,

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FIG 3 Measurement of click interference in timedomain

FIG 2Test setup for RFI field-strengthmeasurements

Shielded chamber

Plotter

IEC bus

Printer

Centronics

DUT


• IF spectrum analysis with resolutionof 1, 3 or 10 kHz over a displayrange from 10 kHz to 10 MHz (option),

• 9 kHz to 2750 MHz tracking gener-ator (option).

The operating concept of ESCS30makes for great measurement con-venience and fast and reliable settingof the receiver. The clear arrangementof the controls – all keys being assignedone function only – and the indicationof the selected parameters such as attenuation, bandwidth and detector(s)on separate LC displays ensure greatease of operation. For solving complexEMC problems, manual measurementoften is the most efficient way, since the operator can make full use of his experience in identifying interferencesources. ESCS30 features the proventest receiver operation with tuningknob, indication of results on an LC display, bargraph and meter as well as acoustic monitoring via the built-inloudspeaker. Marker and zoom func-tions permit in-depth analysis of inter-ference spectra. The level values of the detectors selected are displayed below the diagram in quasi-realtime asa bargraph with peak-hold indication (FIG 4). The audio section is providedwith A0, AM and FM demodulatorswith squelch enabling acoustic identi-fication of signals via the built-in loud-speaker or a headphones output.

System integration anddocumentationThe high measurement speed ofESCS30 is also useful for remote control via a fast controller (interface toIEC 625.2/IEEE 488.2). All functionsof the test receiver can be remotely con-trolled and are supported by Rohde &Schwarz EMI software products.

ESCS30 adheres to the standardizedreport configuration of Test ReceiversESHS/ESVS/ESS so that reports can be compared. A comprehensive test report can be generated on a printer or plotter. It contains all relevant infor-

graphs and final results. All results (scan values as well as test frequenciesand level values) can be checked by theuser on the monitor prior to producinga printout. Additional comments are entered via the line editor, which in mobile testing allows test runs or parameter sets to be marked and doesaway with the need for an external keyboard. The final results are output in graphical and tabular form givinglevels measured with quasi-peak andaverage detectors versus frequency.Levels exceeding the limit lines aremarked.

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Condensed data of EMI Test Receiver ESCS30Frequency range 9 kHz to 2750 MHz

Frequency uncertainty 1 x 10–6

Preselection 10 filters

Noise figure 5 dB (<30 MHz), 9 dB (<2750 MHz)

3rd-order intercept point +20 dBm (<30 MHz), +10 dBm (<2750 MHz)

Bandwidths 200 Hz, 9 kHz, 120 kHz, 1 MHz

Detectors PK, AV, QP

Types of analysis RF spectrum analysis,IF spectrum analysis (option),time domain analysis

Tracking generator (option) 9 kHz to 2750 MHz

Interfaces IEC 625.2 (IEEE 488.2), user port, Centronics


FIG 4 RF spectrum with active markers andbargraph display

Like all full-compliance receivers fromRohde & Schwarz ESCS30 features not only selftest facilities but also auto-calibration routines that ensure adher-ence to the data-sheet specifications.The current-saving circuit design andthe built-in accumulator provide idealprerequisites for mains-independent,portable use.

Volker Janssen; Matthias Keller

REFERENCES

[1] Müller, K.-O.; Stecher, M.: EMI Test ReceiverESS – The world’s first instrument covering 5 Hz to 1 GHz. News from Rohde &Schwarz (1992) No. 138, pp 8 –10

[2] Janssen, V.: EMI Test Receiver ESPC – EMCprecertification measurements for everyone.News from Rohde & Schwarz (1995) No. 149, pp 16 –18

mation required for the reproducibilityof measurements, such as commentsand description, test receiver settings,


Application

Series 200 multichannel radio equip-ment is used for instance for normalstandby or emergency standby oninternational airports. In normalstandby a few multichannel units areused as backups for several single-channel radios, while the emergency

standby radio equipment maintainsminimum radiocommunications in theevent of a total breakdown of a largeradio system made up for instance of Series 200 single-channel radios [1; 2]. Such breakdowns can occur ifcables (for AF, control, power supply)are damaged by lightning or as a resultof careless construction work. In suchcases the standby equipment guaran-tees maximum channel availability andcost efficiency of the entire radiocom-munication system.

However, multichannel radios are notonly required on international airportsbut also by small- and medium-scale

• relief services with stationary or mobile radio equipment, for instancein case of humanitarian missions indisaster areas or trouble spots,

• aviation industry with company-owned test airfields,

• explorers of any kind (oil, gas, ores,minerals, wood, etc) with landingstrips of their own,

• military services in need of simpleand cost-efficient radiocommunica-tions equipment in A3E and fixed-channel mode for ground stations ormobile towers (if the features of theSeries 400U multichannel commu-nication system are not required foroperational reasons).

operators who use them as operation-al radio equipment – especially thecompact VHF Transceivers XU220A for RF power of 25 W or XU250A for50 W (FIG 1). Potential users are:• regional airports for general avia-

tion handling business and privateair traffic,

• rescue services with airstrips of theirown,

• private shuttle services with theirown helicopter landing strips,

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Series 200 multichannel radio equipment

VHF-UHF ATC radiocommunicationsgo multichannelRohde & Schwarz has expanded the existing Series 200 single-channel radioequipment for VHF and UHF communications by adding multichannel equipment.As full-featured system equipment the new generation enables locally or remotelycontrolled radiocommunications on any channel in these frequency ranges.

FIG 1 VHF Multichannel Transceiver XU250Aserves as standby unit on international airportsand as ordinary operational equipment for ra-diocommunications in small- and medium-sizedATC systems. Photo 42 815


Features

The following facilities are common to the single- and multichannel radioequipment of Series 200:• VHF and UHF receiving systems

(with up to eight receivers per 19-inch adapter),

• VHF transmitters and transceivers for 25 and 50 W,

• UHF transmitters and transceiversfor 30 W,

• PC-controlled Remote Control andMonitoring System RCMS.

The multichannel systems feature thesame proven characteristics as the single-channel equipment such as out-standing price/performance ratio, ex-cellent performance data, high avail-ability, advantageous logistics and ser-vice concept (flexible modularity, inte-grated interfaces, test instruments andsoftware, special service kits). The twoproduct lines have the same basic specifications and design. A receivingsystem can be made up of single- aswell as multichannel equipment andconnected to the associated multi-coupler and test generator. The radiosare based on the same modules andsubassemblies and operate with thesame new RCMS software.

Modifications to the single-channel product line have only been made wherever necessary. To name a few attractive innovations:

• digital receiving concept: the use ofdigital processors allows relativelysimple and firmware-controlled ad-aptation to particular specifications,data optimization and improved testfacilities,

• channel spacing (IF bandwidth) inthe VHF range selectable between25 and 8.33 kHz,

• every frequency and preselectedchannel can be locally and remotelycontrolled,

• control interface for external antennafilters integrated into transmitters andtransceivers, which makes the unitsfully system-compatible,

• power supply integrated into trans-mitters and transceivers as standard,which yields cost-efficient logistics,

• new model (.03) of REM Bus DriveUnit GV201 permitting even remotecontrol and monitoring of detachedradio stations (RCMS) without sepa-rate slave PCs,

Thanks to these features and the resulting attractive and future-proofapplications, Series 200 multichannelradio equipment will no doubt proveto be as successful on the interna-tional market as its single-channelcounterparts.

Hans-Günther Klarl

• built-in RCMS for single- and multi-channel equipment: its high flexibil-ity allows various interfaces to beused and meets practically all oper-ational requirements (FIG 2).

REFERENCES

[1] Klarl, H.-G.: Series 200 VHF single-channelradio equipment – The new dimension inATC communication. News from Rohde &Schwarz (1993) No. 140, pp 4 –7

[2] Klarl, H.-G.; Kessler, M.: Series 200 and400U radio equipment – Innovations in ATCradiocommunications: RCMS and 8.33-kHzchannel spacing. News from Rohde &Schwarz (1996) No. 152, pp 14 –16

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Condensed data of Series 200 multichannel radio equipmentFrequency range VHF 118 to 144 MHz

UHF 225 to 400 MHz

Channel spacing 25 and 8.33 kHz, switch-selectable

Preselectable channels 100

Frequency error ≤1 x 10–6 (0 to 40°C)

RF power VHF 50 or 25 WUHF 30 W

Offset mode up to 4-carrier offset

Types of equipment receiving systems, transmitters and transceivers, auxiliary equipment

Remote control and monitoring integrated for single- and multichannel operation by means of Software GC201-S (.03)


FIG 2Remote Control andMonitoring System

RCMS of Series 200radio equipment

is suitable for practi-cally every type of

complex ATC radio-communications

system.

RCMS PC

Single-channelsubsystem

Multichannelsubsystem

Single-channelsubsystem

Multichannelsubsystem

Local area

Remote area (country-wide)


Increasing communication traffic andexpansive networking call for trans-mitters to set up links on more than onechannel. Mostly, simultaneous use ofmany radio networks on different trans-mit frequencies is required. The classicsolution to this task is a transmitting antenna with the corresponding trans-mitter for each radio network. If nobroadband antenna is used, a trans-mitter-specific antenna tuning unit is required where several RF power relayshave to be switched whenever the frequency is changed. To keep cross-

coupling between the transmitters low,a minimum distance between the anten-nas has to be maintained, which meanslarge space requirements. Problemati-cal with this approach is that – duringthe planning phase of such a system –there is relatively high uncertainty as far as the number of simultaneously operated radio networks is concernedand that any redundant transmitterscannot be used for increasing power in critical situations. HF BroadbandSystem XB2900 from Rohde & Schwarzis the right solution here, since it offers

simultaneous operation on a maximumof 32 channels into up to three broad-band HF antennas.

Configuration of HF broadband systemHF Broadband System XB2900 com-prises RF components of the XK2000family, a power management unit aswell as a supervisory control system forconvenient operation.

RF componentsDigital 1-kW HF Transceiver XK2900consisting of receiver/exciter, 1-kWpower amplifier as well as power supply [1] forms the core of the HFbroadband system. These standardcomponents are also ideal for use inclassic applications with narrowbandtransmitting antennas. As Receiver/Exciter GX2900 has digital signal processing at the IF, a number of inter-esting features are offered such aseleven receive bandwidths as well asthe digital voice compressor to name afew examples. Operation is possiblevia softkeys but also via the serial interface. The basic modules and op-tions introduced for 150-W TransceiverXK2100 [2] and 500-W/1-kW Trans-ceivers XK2500/2900 [1] can also be used for HF Broadband SystemXB2900.

The MOSFETs in 1000-W Power Amplifier VK2900 provide sufficientpower reserves. The amplifier controlwith its numerous protective circuits ensures high reliability of the amplifiereven under extreme operating condi-tions.

The receiver/exciter and the poweramplifier are powered by Power Supply IN2900.

Combiners FK2910 serve for com-bining the RF outputs of two power amplifiers. If two of these combiners areto be connected, a Combiner FK2920with a higher power rating is used. Ifsignals of equal phase are applied tothe combiner inputs, roughly twice the

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HF Broadband System XB2900

Custom-tailored shortwave communications Components for combining several 1-kW or 500-W transmitters/receivers extendthe successful HF Transceiver Family XK2000 to HF Broadband System XB2900.Simultaneous transmitter operation on a broadband antenna on different chan-nels and output power increases are now possible. Since the RF power compo-nents are passive and broadband, frequency-agile and reliable data and speechlinks can be set up according to customer requirements with the tried and testedoptions of the XK2000 family.

FIG 1 HF Broadband System XB2900 with 16 1-kW transceivers Photo 42 580/2


power is available at the output. Highdecoupling at the combiner inputs al-lows different signals to be emitted atthe same time but the output power iscut by half. The remaining power is tak-en to external absorbing resistors toprevent the power amplifiers warmingup unduly.

Triplexer FK2950 combines threetransmitting antennas such that low-lossradiation between 2 and 30 MHz isobtained. Antenna switches are not required.

Power management unitPower Management Unit GV2900plays a major role in the HF broadbandsystem since it processes all the infor-mation of the connected RF and controlcomponents. It also evaluates the con-trol telegrams of the receivers/excitersand passes them on to the allocatedpower amplifiers. At low signal levels,the RF signals of the receivers/excitersare distributed to one, two or four power amplifiers. Moreover, two powermanagement units can be cascaded so

that up to eight 1-kW power amplifierscan be controlled via an exciter. Thecontrol telegrams are evaluated in realtime in a field-programmable gatearray.

All the components of the HF broad-band system are continuously moni-tored and support a built-in test. Thepower management unit plays a centralrole: it directs the monitoring of the RF components and responds to errormessages. Simple error analysis en-compasses a loop test of all the controlinterfaces and monitoring of the levelsof the RF interfaces by means of aninternal test generator.

Control systemThe HF broadband system is controlledby a controller with a graphical userinterface. Additional HF, VHF and UHFtransceivers can also be controlled viathis user interface. The phone exten-sions to wired and wireless communica-tion can be allocated via an integratedintercom system. The system can alsobe operated without a controller. In this

case the power management unit isconfigured once with a standard PC. Hardware configurations are notrequired.

Application

FIG 1 shows an HF broadband systemwith 16 HF Transceivers XK2900. In itsmaximum configuration the system con-sists of 32 HF transceivers. The outputsof two power amplifiers are combinedby broadband combiners. The outputsignals of these combiners are taken to a broadband transmitting antennavia several Combiners FK2920 or to three transmitting antennas via Triplexer FK2950. The reduction in the number of transmitting antennasthus achieved is especially interestingfor use onboard ships. Its high flexibilitymakes the system also ideal for land-mobile applications. Each transceiver/exciter can be used as a complete receiver – eg for full-duplex mode – provided that no power amplifier is assigned to it.

The whole HF broadband system canbe divided into scaleable subsystemseach comprising a Power Manage-ment Unit GV2900 per block (FIG 2).Up to four receivers/exciters and four power amplifiers can be con-nected to each power managementunit. Since it is not necessary to fullyequip the power management unitwith receivers/exciters and power amplifiers, high flexibility is offered to meet customer requirements. If notall the components are available,transmission will be maintained with the remaining power amplifiers.The logic connection between the receivers/exciters and the allocatedpower amplifiers is made from thepower management unit through commands. The allocations can bemodified within seconds without theuse of any RF power relays, which aresubject to wear and tear. Commandand monitoring operations are per-formed by the supervisory controlsystem via a serial interface per power management unit.

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FIG 2 Configuration of subsystem with four 1-kW transceivers

FK 2920

FK 2910

Block 1

Block 2

Block…

Block 8

Triplexer

FK 2910

Power Management UnitGV 2900

Receiver/Exciter GX 2900

Power supply

1000-Wamplifier

Combiner

CombinerFK 2920


With a power management unitequipped with a single receiver/exciterand four power amplifiers, the systemdescribed can also be operated as anHF transceiver with increased outputpower. As far as control is concerned,this system behaves like a 1-kW Trans-ceiver XK2900.

Holger Buchholz; Hendrik Köhler

REFERENCES

[1] Träger, R.: HF Transceivers XK2500 andXK2900 – The new members of HF Trans-ceiver Family XK2000. News from Rohde &Schwarz (1997) No. 153, pp 12 –13

[2] Helmke, B.; Wachter, G.: HF TransceiverXK2100 – Digital shortwave for future-proof,long-haul communication. News from Rohde& Schwarz (1994) No. 144, pp 4 –7

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Condensed data of HF Broadband System XB2900 with four transceivers

Frequency rangeTransmission 2 to 30 MHzReception 10 kHz to 30 MHz

Output power into 50 Ω 1 x 3 kW/2 x 750 W/4 x 190 W(±0.5 dB each)

SWR at output <3

Frequency spacing of transmitting amplifiers >1%

Time for frequency change <25 ms

Switchover time T/R <10 ms

Time for change of combining mode <3 s (typical)

Operating temperature range –25 to +55°C

Remote-control interfaces RS-422/RS-485 or RS-232


Feedback A letter from Switzerland

Engineer E. Meyer-Hofer, formerly owner of a radio and TV sales and service center in Rothrist in Switzerland, writes the following:

“The great admirer of Rohde & Schwarz that I am,I first came into contact with Rohde & SchwarzT&M equipment as a young engineer in the early40s. I have ever since been fascinated by how highthe scientific standard of this equipment was eventhen, so in my professional life R&S came to be themake of my choice whenever I had to buy testequipment and had the money. I am enclosing aphoto of several nostalgic R&S measuring instru-ments, which I kept after my retirement and whichI would not want to give away, because they stillwork with all their functionalities.”

We would like to thank Mr. Meyer-Hofer very muchfor his letter and wish him many more years of enjoyment with his Rohde & Schwarz equipment.


Uses

Broadcast cable networks are increas-ingly expanding to digital programs,not only in the cable headends of Deutsche Telekom but also in those of private national and internationaloperators. QAM Transmitter CT100QT(FIG 1) from Rohde & Schwarz was developed for feeding digital TV programs from fiber-optic cables orsatellites into the broadband cablenetwork. Notable features of this trans-mitter are its compact design, systemcompatibility, remote-control capabil-ity and an attractive price, which alsomakes it a candidate for smallersystems. CT100QT comprises a QAMmodulator and an upconverter so thatdigital TV program data available at its output are ready to be fed intothe broadband cable. For special applications, the modulator and up-converter can also be supplied as separate modules, ie ModulatorCT100QM and Upconverter CT100UP.The CT100 components are fully compatible with CATV HeadendSystem CT200 [1] and thus ideal for supplementing existing analogcable headends from Rohde &Schwarz with digital programs. Thebenefits of CT200 such as activestandby, remote control via PC andmodem or self-monitoring are also offered by CT100 modules. Moreover,an additional RS-232-C interface is integrated for firmware updates.

Operation

The operation of QAM TransmitterCT100QT is fully digital up to the IF,which can be selected in 1-MHz stepsbetween 31 and 41 MHz, and thusprovides quadrature amplitude mod-ulation in excellent quality. Blocks of188 or 204 bytes can optionally beused for input data. At a frame lengthof 204 bytes the last 16 bytes are assigned for error control. All QAMmodes can be set, ie 16, 32, 64, 128and 256QAM with DVB-compliantmapping [2]. The signal is shaped bymeans of a root-cosine roll-off in linewith DVB. Any other spectral shaping ispossible by loading the shaping filtervia the PC interface. The output datarate can be selected freely between500 kbit/s and 55.2 Mbit/s indepen-dently of the input data rate. The onlyrequirement to be met is that the ap-plied net input data rate should be lessthan the set output rate. The two datarates are matched by removing or adding so-called stuffing blocks. The jitter thus caused in the time stamps iskept below the range stipulated in theETSI standard by correction of the PCR (program clock reference) values.The asynchronous serial interface (ASI)and the synchronous parallel interface(SPI) are implemented as data inputs (FIG 2). The converter transforms thespectrum generated at the IF to the RF in inverted form. The user can definewhether mapping is to comply with the

specs at the IF or RF. The frequency isselected via the passive channel filter,which is plugged externally to the module to make for easy exchange.Frequency resolution of 10 kHz allowsalmost any channel spacing to be chosen.

Data processing and channel coding

Incoming data (MPEG2 transportstream) are converted into a parallelTTL signal with a clock signal and arewritten into an FIFO memory withoutstoring the stuffing blocks. The fill state

of the FIFO is monitored and, if suffi-cient data are available in the FIFO, awhole block is read out. Otherwise, astuffing block is inserted into the datastream. The stuffing block consists of the sync word and PID (program identification). A continuous PRBS(pseudo-random bit sequence) is sent inthe data section of the stuffing block, iethe PRBS generator is stopped duringthe header. The data rate defined by

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FIG 1 Highly cost-effective and modular QAMTransmitter CT100QT adds digital to analog programs in cable headends. Photo 42 823

QAM Transmitter CT100QT

Processing digital TV signals for cable headendsA small cost-effective module is all that is needed to add digital programs to analog TV programs in cable headends. QAM Transmitter CT100QT, which is fully compatible with the successful CATV Headend System CT200 from Rohde &Schwarz, processes digital vision and sound signals for feeding into the broad-band cable together with analog signals.


the user will thus be used. The time delay of the PCR values is corrected byrecalculating the time stamps. If no dataare present at the selected interface, a continuous PRBS signal is sent that is interrupted by the sync byte only. The PRBS signal is not affected by energy dispersal, error control andinterleaving. In addition to this auto-matic switchover, transmission can befixed to PRBS or data.

A channel coder then scrambles theprocessed data to avoid long se-quences of 0s or 1s. After every eighthblock the scrambler is reinitialized and the sync byte inverted to mark this event. In the following block, 16 bytes are calculated for Reed-Solomon error control and added to the data of a block. The subsequentinterleaver distributes the bytes of ablock among twelve blocks so thatblock errors occurring in the channelcan be corrected.

Mapping and spectral shaping

Data are next combined to new symbols according to the QAM mode:for 64QAM symbols with 6 bits persymbol are generated. The two upperbits are phase-differentially coded andform a set of I and Q values for each ofthe 64 symbols using a mapping table.The two I and Q signals are subjected

to fourfold oversampling and then spec-trally shaped in the interpolation filter(in line with root-cosine standard).

To ensure that the D/A converter always receives roughly the same datarate, irrespective of the symbol rategenerated by the data section, the signal is again oversampled at a variable rate. The digital mixer ampli-tude-modulates two orthogonal IF car-riers with the digital signals and finallyadds them to a carrier modulated inamplitude and phase. The two carriersare generated by direct digital synthe-sis, which ensures an accurate phaserelation between them. I/Q imbalance,ie difference in I and Q signal ampli-tudes, is excluded due to the digital processing of the baseband (I and Q)signals. Since the amplitude modula-tion of the two carriers is performedthrough multiplication of two digital values, highly effective carrier suppres-sion is achieved.

D/A conversion and analog filtering

An FIR (finite impulse response) filterprocesses the digital IF signal and compensates for the sine(x)/x roll-offgenerated in the D/A converter. The IF level can be varied in a range of approx. 6 dB by means of the D/A converter. The subsequent analogbandpass filters the desired spectrum

from the periodically recurring spectra.The signal can be reduced by 6 dB witha switchable attenuator. An external IF input allows a frequency multiplex tobe generated at the IF. The external IFsignal is added to the internal signalnon-reactively in an active adder stageand then taken to the converter.

Conversion to RF channel

After measuring the level of the IF sumsignal and setting the IF level, the QAM signal is converted to the RF channel by inversion. Unwantedmixture products are filtered out by a passive filter plugged externally to the module. If the frequency is to bechanged, the filter simply has to be exchanged. The channel filter itself defines the synthesizer setting of the local oscillator. A signal for controllingthe IF setting element is calculatedbased on a comparison of RF and IFlevel, thus keeping the output level con-stant in all frequency ranges. The RFoutput signal is provided at two outputswith different levels from one another.

Clock-signal generation

All signals used in the module (exceptfor the input data clock) are derivedfrom a highly stable 10-MHz crystal oscillator. All output signals thus havethe same stability as the reference. Fordigital processing a clock signal with2n times the symbol frequency is gener-ated by a synthesizer (n depends on theselected output data rate) and all other clock signals are derived throughdivision. The signal for converting the IF signal into the RF channel is providedby a synthesizer with the 10-MHz signalas a reference. The whole frequencyrange is covered by two oscillators byswitching between them and variablydividing their frequency.

Control and self-monitoring

All functions of CT100QT such as IF,symbol rate, QAM mode and outputlevel can be remotely controlled via a serial interface. A large number of

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FIG 2 Block diagram of QAM Transmitter CT100QT

InterfaceStuffing,

PCRcorrection

Channelcoder

Over-sampling

I/Qmodulation

Anti-aliasing

filter

D/Aconverter

Clocksynthesizer

Bandpassfilter

InternalIF

MPEG2transportstream

ASI

SPI

Localoscillator,

synthesizer

100-MHzreference

RFconverter

Channelfilter

Outputamplifier

Internal IF

External IF

RF forfeedingintobroadbandcable

Microprocessor SerbusRS-232-C


parameters are also continuously moni-tored and an error message is issued ifthe tolerance is exceeded. The clockfrequencies of the digital section tooare measured and the output signal is switched off on the occurrence of anerror. Adjacent channels will thereforenot be disturbed by too wide a QAMspectrum. The signal is also switchedoff and an error message issued if thesignal at the RF output is too high.

Walter Bschor

REFERENCES

[1] Schönberger, P.; Sturm, P.; Scheide, R.: CATVHeadend System CT200 – CATV signal processing intelligent, compact, versatile.News from Rohde & Schwarz (1995) No. 148, pp 23–25

[2] European Telecommunications Standards In-stitute ETSI: Digital broadcasting systems fortelevision, sound and data services; framingstructure, channel coding and modulationcable systems. Draft prETS 300 429 (1994)

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Condensed data of QAM Transmitter CT100QTModulation 16, 32, 64, 128 and 256QAM

Inputs ASI (75 Ω)/SPI, LVDS (100 Ω)

Output data rate 500 kbit/s to 55.2 Mbit/s

Transmit frequency range 108 to 862 MHz

RF output level 1/2 72 to 87 dBpW/83 to 95 dBpW

Bit error rate <1 · 10–9 (with corresponding demodulator)


ReferenceOne wavelength ahead

This is the motto under which the south Germancompany of Mikes Product Service GmbH, a subsidiary of TÜV Product Service GmbH, offers its services to customers all over the world.Mikes Product Service is a leading, independent,accredited test lab for approval measurementsand product certifications in line with national,European and international guidelines in thefields of EMC, telecommunications and security.On open-area test sites, in shielded cabins andanechoic chambers equipped with state-of-the-art test instruments, Mikes Product Serviceperforms EMC measurements on medicalsystems, industrial machines, µP controls, labora-tory instruments, vehicles, vehicle components,for instance. Testing terminal equipment such asCB radios, car immobilizers, cordless telephonesand telemetry systems also belongs to the widerange of services offered by the test specialist.The TÜV Product Service group with more than40 branch offices and laboratories in Europe, theUS and Asia and over 250 EMC and telecommu-nications experts is the largest independent EMCcompetence center worldwide.

To be able to adhere to the corporate principle “Short turnaround time, high competence, qualityand flexibility” Mikes Product Service hasequipped its test labs with the latest EMC test in-struments and systems from the comprehensiveRohde & Schwarz product range.

The Mikes brochures below illustrate the spectrum of measurements performed by this company. Sö


The results obtained from the planningof modern nationwide paging networksshow that countries with a size and infrastructure like Germany requiremore than 1000 transmitter sites for fullcoverage. Depending on the pagingstandard and frequency range as wellas the type and number of paging callsto be transmitted, these paging basestations can be equipped with one or more transmitters*. The advancedconcept of Paging Transmitters SD330and SU330 (FIG 1) covering differentpaging standards, frequency ranges,power classes and hardware configu-

rations enables fast installation, retro-fitting or upgrading of radiopaging net-works at a minimum of investmentcosts.

In addition to basic features such asavailability in all international fre-quency ranges and suitability for allmodern paging methods, TransmitterFamily SU330/SD330 has especiallybeen designed to minimize cost ofownership:• optimized coverage with output

power between 20 and 400 Wand maximum modulation accuracyat the same time,

• different protocols and baud ratessupported exclusively by software,

• uniform, intelligent and comprehen-sive concept for operation, adminis-tration and maintenance,

• multilevel maintenance strategy withon-site service of paging transmittersby local electricians,

• easy integration into existing com-munication networks as well as intocost-optimized and unobtrusive out-door cabinets.

Technical design –modular and flexiblePaging Transmitter SU330 generates aspectrally pure VHF signal modulatedto the paging standard (FIG 2), where-as SD330 generates the correspondingUHF signal. Via a directional coupleroutput the forward and reflected powerat the transmitter output can be deter-mined; a monitor output allows a spec-trum analyzer or similar test equipmentto be connected. An I20+ interfacecompatible with the de-facto standardI20 supplies the transmitter control unitwith all the configuration informationand modulation data required for con-trolling the modules. House alarms canbe connected at the input/output inter-face (option) and transmitted via the I20+interface. The outputs of this option canbe used to switch external equipment.A commercial PC can be connected tothe front panel of SU330 for diagnos-tics and configuration tasks. The highstability of the transmit frequency neces-sary for single-frequency network oper-ation (simulcast) is guaranteed by anexternal reference frequency, which isusually supplied by the controller ineach paging base station. An oven-con-trolled reference oscillator can be inte-grated as an option.

Using the same hardware, TransmittersSU330/SD330 digitally generate alltypes of modulation required for the relevant paging standards. This en-ables network operators to change to adifferent paging standard by firmwaredownload and remote control of thetransmitter parameters – “on the fly” –without having to manipulate the exist-ing network infrastructure. Channelspacing and frequency deviation canof course be adapted to national re-quirements. The table in the blue boxlists the technical parameters of themodulation types and paging stan-dards supported by SU330/SD330.

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Paging Transmitters SU330/SD330

New transmitters for nationwide coverageUltra-high availability at low cost of ownership is ensured by VHF and UHF Pag-ing Transmitters SU330 and SD330 for nationwide paging networks according to ERMES, POCSAG, FLEX and APOC standards. No matter whether for new installation, retrofitting or upgrading – Paging Transmitters SU330/SD330 can be installed in an extremely short time and adapted to the specific task simply by software.

* Rieder, T.: Paging System P2000 – Flexible,multiprotocol radiopaging system. News fromRohde & Schwarz (1996) No. 151, pp 25–27

FIG 1 VHF Paging Transmitter SU330 for out-put power of 200 W Photo 42 622


Ultra-high reliability andcost effectiveness

One of the most important parametersfor network operators is the reliabilityof the infrastructure used. If redun-dancy becomes necessary because ofpoor MTBF (mean time between fail-ures) of the infrastructure components,the investment costs will increase disproportionately to the achieved improvement in reliability. Thanks to the very low temperature of the powerstages and good heat dissipation of the isolators and filters, TransmittersSU330/SD330 guarantee extremelyhigh MTBF. Even at ambient tempera-tures of 50°C the maximum heatsinktemperature is just 20°C higher, whichmeans an MTBF of over 28,000 hours.

• frequency and duration of on-siteservicing due to faults,

• qualification of service personnel,• equipment required for on-site ser-

vicing.

Paging Transmitters SU330/SD330come very close to the ideal of a com-pletely maintenance-free infrastructure.The components themselves and on-siteinstallation are of extreme service-friendliness:• A continuous built-in test monitors

all relevant parameters and signalsevery limit violation.

• The OAM system allows defects tobe identified down to module levelbefore the service personnel sets outto the site.

• Defective modules can immediatelybe identified on-site thanks to front-panel LEDs, which does away withthe need for specialized knowledge.

• The modules are easily accessibleand there is no risk of interchangingor incorrectly connecting them in theevent of a replacement.

• The only regular service necessary isto check the long-life fans every twoyears.

Network operators are thus in a posi-tion to introduce a cost-optimized,three-stage service concept: When de-fects are clearly identified (red LEDs),the module concerned is replaced by a qualified local electrician. In case of more complex faults the defectivemodules are localized at the site by aspecially trained service technician using a PC and optical indications fortroubleshooting, and then the modulesare replaced. Servicing down to com-ponent level is performed either by Rohde & Schwarz or by the networkoperators’ service centers.

Local status indication

LEDs give a fast overview of the statusof an active paging transmitter withoutany tools or manual operation beingnecessary. The LEDs inform about thefollowing parameters: power supply,status of interfaces and built-in test of individual modules. The well-knowncolours of the traffic lights are used forsignalling: red means “Stop” indicatingmodule or part no longer operational,yellow is for signalling of operationalparameters, and green is for “Go” –showing status OK, configuration suc-cessful. A PC can be used for acquiringand monitoring further status messagesand measured values of the trans-mitters. The result log in the transmitterstores the parameters of ongoing oper-ation in line with the required con-figuration and serves for instance as a basis for the statistical evaluation ofsite-related operational data.

Thomas Rieder; Michael Müller

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The OAM functions (operation, admin-istration and maintenance) of a mobile-radio network are closely related to theservice concept for the infrastructure.The transmitters in the base stations areof particular importance in this contextsince they are components that may ex-ist many times within the system. Theoperating costs are mainly determinedby the following factors:• frequency and duration of regularly

performed service work,

Condensed data of Paging Transmitters SU330/SD330Frequency range SU330/SD330 146 to 175 MHz/440 to 475 MHz

Output power SU330/SD330 <400 W/<100 W

Paging standards ERMES, POCSAG, FLEX™, APOC™incl. combined on-the-fly mode

OAM concept widely expanded functions as comparedto I20 de-facto standard, I20+ for remotecontrol, RS-232-C for local PC control

MTBF >200,000 h (25°C)/>28,000 h (50°C)


FIG 2 Block diagram of Paging TransmitterSU330 (options yellow)

Modulation Paging standard Transmission data Channel data raterate in kbit/s in kbit/s

FSK POCSAG 0.512/1.2/2.4 0.512/1.2/2.4APOC 1.2/2.4/3.2 1.2/2.4/3.2FLEX 1.6/3.2 1.6/3.2

4FSK ERMES 6.25 3.125APOC 4.8/6.4 2.4/3.2FLEX 3.2/6.4 1.6/3.2

RF monitor

RF powerfref

I20+

Input/output

interface

Referenceoscillator

Exciter FilterAmplifier

Control unit


The end of this millennium is seeing therise of a new form of global communi-cation, which makes use of satellites.This form of communication involvesportable terminals that allow blanketworldwide coverage and thus supple-ments local terrestrial networks such as GSM. When planning this type ofcommunication, various satellite con-figurations were considered. Initiallyconsiderations focused on the fre-quently used geostationary satellites, ie satellites orbiting at the rotationalspeed of the earth. When viewed fromthe earth, these GEO (geostationaryearth orbiting) satellites appear to bestationary in the sky. However, this stateof equilibrium is only possible at a distance of around 36,000 km from the earth, so the terminals used must

have directional antennas, and a trans-mission power of around 25 W. A verycompact terminal of this type is Sat-phone SP1600 from Rohde & Schwarz[1], which is the size of an attachécase. The use of terminals the size of mobile phones is only feasible withsatellites orbiting the earth at a distancewell below 36,000 km. Successful com-munication systems so far have usedMEO (medium earth orbiting) satellitesflying at medium altitudes (approx.10,000 km) and LEO satellites orbitingat low altitudes (approx. 1000 km).

Space radio service monitoring

For space radio service monitoring [2]these latest developments bring aboutthe need for satellite receive antennas

capable of tracking satellites at low altitudes. The most important tasks inmonitoring LEO satellites are:• monitoring the radio frequency spec-

trum in order to detect and identifysatellite emissions,

• allocating frequency bands andsupervising their use,

• determining satellite position andorbit stability,

• measuring and documenting thecharacteristics of satellite emissions,

• examining radio interference causedby satellites,

• examining radio interference causedby ground facilities,

• detecting unauthorized transponderuse.

Rohde & Schwarz has been offering favourably priced antenna and receiv-ing systems [3] for this range of tasksfor some time. Non-geostationary satel-lites, on the other hand, must be con-tinuously tracked while measurementsare being performed. In addition, un-known satellites have to be trackeddown and their orbits determined. Rohde & Schwarz has now developedand successfully put into operation a receiving system that meets these requirements.

Monitoring system with Antenna AS809At the heart of the monitoring system for LEO satellites is Antenna AS809,which allows polarization-independenttracking according to the monopulseprinciple – ie independent of the type of signal being dealt with (FIG 1). Theantenna reflector and the positioningsystem were developed in cooperationwith Vertex, the former Krupp Industrie-technik. Reflectors may be 8 to 11 m indiameter.

The frequency range is 1 to 18 GHz,but thanks to the high-precision reflectorit may also be extended to cover theVHF and mm ranges. The antenna ispart of the fully processor-controlled Radiomonitoring System RAMON [4],whose receiving components allow a

Articles

Satellite Tracking Antenna AS809

Radiomonitoring LEO communication satellitesRohde & Schwarz has developed a broadband microwave antenna to be used for varied monitoring tasks in future satellite communications. This antenna can receive signals emitted by fast-moving LEO (low earth orbiting) satellites inaddition to signals from geostationary satellites.

FIG 1Satellite TrackingAntenna AS809 for 1 to 18 GHzPhoto 41 722/9


no-gap conversion of a wide frequencyband to the intermediate frequencyrange 70 MHz (FIG 2).

A glance at the specifications of Satellite Tracking Antenna AS809 willreveal that the antenna has plenty of reserve for future LEO communicationsystems.

Dr. Klaus Rieskamp

REFERENCES

[1] Böhler, U.: Shortwave radio or satellite com-munication? News from Rohde & Schwarz(1995) No. 149, pp 57– 59

[2] ITU Spectrum Monitoring Handbook 1995,chapter 4.1

[3] Schiller, M.; Sigl, G.: Antenna AC002B5and Receiving System EA002B5 – Processor-supported monitoring system for 0.1 to 18 GHz. News from Rohde & Schwarz(1995) No. 147, pp 7– 9

[4] Ehrichs, R.; Holland, C.; Klenner, G.: Radio-monitoring System RAMON – Customized radiomonitoring from VLF through SHF.News from Rohde & Schwarz (1996) No. 151, pp 19– 21

Articles

Condensed data of Satellite Tracking Antenna AS809Diameter ≤11 m

Frequency range 1 to 18 GHz

Bandwidth 50 kHz to 40 MHz

Polarization V/H linear, RHCP/LHCP

Signal channel independent of tracking

Side-lobe suppression using extra antenna

Tracking 3-channel Σ/∆ monopulse

Search antenna for sector and spiral search

Angular speed <15°/s (azimuth)/<7.5°/s (elevation)

Angular acceleration <7°/s2

Power consumption approx. 60 kVA


FIG 2 Receive components of Radiomonitoring System RAMON serve for processing data providedby Antenna AS809. Photo 41 515/4

Test hintTest signals with analog and digital modulation for vehicle information systems

With more and more cars on the road, intelligenttraffic control and management systems are gain-ing in importance in keeping the traffic flow going,especially in cities and on highways. The first,large-area system for complete traffic manage-ment was introduced in Tokyo and its surroundingareas in 1996 under the name VICS (vehicle infor-mation and communication system). VICS collectstraffic information (for instance about traffic jams,road blocks or car park occupancy) in an area ofabout 500 km2, processes these data in a controlcenter and passes the information on to the car drivers via microwave transmitters, infrared transmitters and VHF FM sound broadcasting. In

the cars, the data are processed by a navigationsystem and indicated on a display.

Signal Generator SME03 with its versatile digitaland analog modulation characteristics is an idealsource for the development and production of VICScomponents – in particular microwave transmittersand receivers. The microwave transmitters operateat a frequency of about 2.5 GHz. The data suppliedby VICS are GMSK-modulated onto the carrierwith a data rate of 64 kbit/s. This digital modula-tion is superimposed by analog amplitude modula-tion (modulation index 10%, modulation frequency1 kHz), which is analyzed for position determina-tion. The test signal on the right shows the frequen-cy deviation and the amplitude of the modulatedcarrier signal versus time as furnished by SME03.SME03 fully satisfies the exacting requirements ofVICS regarding modulation quality and synchron-ization of analog and digital modulation.

Mathias Leutiger Reader service card 154/08

ROHDE & SCHWARZ

SME 03

eg microwave transmitter

DUT


Rohde & Schwarz, a world marketleader in mobile-radio measurements,and its US partner company Tektronixhave jointly developed a mobile-phonetester for the US mobile-radio systemCDMA to IS95 standard: Digital Radio-communication Tester CMD80 (FIG 1).It also incorporates the technologyneeded for measurements in the pre-decessor analog AMPS network, whichis still in use. CMD80 measures the RFand AF parameters of mobile stationssupporting both standards or dual-modeequipment in development, productionand service with the aid of network-spe-cific signalling. It covers the 800-MHzband (cellular radio mobiles for CDMAand analog AMPS), the 1900-MHzband (PCS mobiles for CDMA, PCS =personal communication system) andthe 1700-MHz band for the Koreanvariant of CDMA.

GSM was the first fully digital mobile-radio network. It has been well estab-lished in Europe and is now spreading

worldwide. The American response tothe successful European standard wasCDMA, set down in standard IS95.This mobile-radio system is competingworldwide with GSM. In contrast to mobile-radio network operators, it isnot for Rohde & Schwarz to opt in favour of one or the other of these two competing standards. Rohde &Schwarz offers T&M technology for allmajor digital mobile-radio networks.T&M experience gathered throughworking with one network may be used beneficially with another. Special features of the individual networks aretaken into consideration. The CDMAsystem has a number of such specialfeatures with implications for the measurements themselves:

• A single subscriber occupies 100%of the radio channel resources (timeand bandwidth). Every further sub-scriber will require the same. Thismeans that each subscriber is a po-tential source of interference for all

the others. For a subscriber at a certain distance from a base stationnot to be blocked by another subscriber close by, the signals of all mobiles are required to have approximately the same level at the base station. So it is necessary toensure through measurements thatthe mobile transmitter has sufficientdynamic range and that it is able to adjust its output power fast andexactly (range of open-loop powercontrol, time response of open-looppower control, FIG 2, range ofclosed-loop power control). Essentialfor network operation is the reliablepower adjustment of each and ev-ery mobile station.

• CDMA signalling is as complex asin any other network. Some aspectsare particularly critical, requiringspecial care on the part of the testerfor the system to work smoothly. Before a mobile is linked to the net-work, it is not subjected to powercontrol from the base station. Themobile therefore has to probe intothe network at very low power (random access, access probe out-put power). Accessing the networkwith high power could lead to all active subscribers being blocked.This signalling procedure and othersof similar complexity are offered by CMD80 to guarantee smooth network operation. The remainingsignalling serves for setting the mobile phone into a state in whichRF and AF measurements can becarried out.

• Another consequence of the aboveis that the receiver of a mobile station is confronted with a largenumber of simultaneous signals. Thebase station emits not only the signalto be received by the mobile, but at the same time and at the samefrequency also the signals for the

Application notes

CMD80: measurements for CDMA and AMPS mobiles

FIG 1 Digital Radio-communication Tester CMD80 – specialist for CDMA(code-division multiple access) and AMPS (advanced mobilephone service)Photo 42 816/1


remaining mobiles plus a synchron-ization aid for all mobiles. On top ofall that, interference from other cellsis also present. For this reason, nu-merous variants of receiver testinghave been worked out. Besides theuseful signal, CMD80 simultaneouslyprovides a large variety of usefuland interfering signals for receivertesting.

• With all subscribers communicatingon the same frequency, anyone candisturb anyone. The positive side ofthe coin is that while an active sub-scriber is not speaking and thereforenot transmitting (which, according tostatistics, is the case in more than50% of the time on average for bi-directional speech), his mobile does

not produce any interference, there-by releasing system capacity for additional subscribers without anyorganizational efforts. The variablerate speech coder, which reducestransmission activity in three stepsfor reduced speech activity, pro-duces some special characteristicsrelevant for measurements whichhave no equivalent in GSM net-works. Transmission activity is re-duced by transmitting only at irreg-ular intervals, but with nominal power during those periods. There isa special power ramping measure-ment function dedicated to this char-acteristic (gated output power).

Bearing these facts in mind, Rohde &Schwarz made a careful selection ofmeasurements to be performed by Digital Radiocommunication TesterCMD80. A considerable number of themeasurements and signalling opera-tions implemented in CMD80 are simi-lar to those in other networks. These aresupplemented by CDMA-specific fea-tures (compiled in blue box top left).

CMD80 also offers transmitter mea-surements revealing more than what isstipulated in the standard specifica-tions. Measurements to standard onlyhave to differentiate between good and bad units, while the additionalmeasurements performed by CMD80also provide detailed information onthe possible origins of faults. Thesemeasurements include error vectormagnitude, phase error and magnitudeerror (each with peak value, rms valueand parameter versus time), carrierfeedthrough, IQ imbalance as well as an audio test (acoustic echo)

and checking operating voltage andcurrent.

In the US, cellular phones were first operated in the analog networkAMPS. Succeeding systems with higher spectral efficiency were used in thesame 800-MHz band to supplementand provide additional capacity to the AMPS network. Each of these succeeding networks is required to beable to work with the original networkin dual mode, and this is likely to remain so in the foreseeable future.Therefore CDMA mobiles must also be able to work with AMPS in the dual mode. Consequently, measure-ments have to cover both modes aswell. This is no problem for CMD80:the blue box below shows an overviewof the available AMPS measurements.In addition, a handover function allowslinking the two systems CDMA andAMPS.

Application notes

Thomas Maucksch


AMPS measurements by CMD80 to IS55

SignallingBroadcast system informationRegistrationCall setup mobile to baseCall setup base to mobilePower change Frequency changeMobile-initiated call releaseBase-initiated call release

Transmitter testCarrier frequencyPower/standby power/access powerModulation deviation limitingTransmitter audio responseHum and noiseModulation distortion and noiseOverall peak deviationFrequency error (supervisory audio tone)Peak deviation (SAT)Frequency error (signalling tone)Peak deviation (ST)Peak deviation (audio)

Receiver testReceiver sensitivity (SINAD)Hum and noiseHarmonic distortionReceiver audio frequency response

CDMA measurements by CMD80 to IS98

SignallingBroadcast system informationRandom accessRegistrationCall setup mobile to baseCall setup base to mobilePower change Frequency changeMobile-initiated call releaseBase-initiated call release

Receiver testReceiver sensitivity and dynamic range

Transmitter testFrequency accuracyWaveform qualityRange of open-loop output powerTime response of open-loop power controlAccess probe output powerRange of closed-loop power controlMaximum RF output powerMinimum controlled output powerStandby output power and gated output power

FIG 2Parameter versus time of mobile station power with tolerance limits


Continuity check module Cocheck II for use with TSA [1– 3] and TSU [4] tester families allows most soldering defects and insertion faults of ICs to be detected without expensive digitaltest configuration.

It is hardly necessary to emphasize the benefits of classic analog-digital in-circuit testing (ICT) for the detection oftypical production faults. Especially thetypical SMD boards fitted with high-pincount, complex ICs call for three requirements which have their price:

1. high digital pincount of the tester,2. library elements for various types of

ICs,3. accessibility of all nodes.

Basically, a digital tester configurationis much more expensive than a purelyanalog one. Another point is that due to high-pincount ICs a large number of digital channels must be available simultaneously, so that in systems withmultiplex operation more pins have tobe provided than actually needed. Au-tomatic program generation is simplefor instance if a test model is available,as is the case for all standard ICs in the library. For customer-specific andprogrammable ICs, this may involveconsiderable extra time and money tocover each individual program. If somenodes become inaccessible, it is not just the test of the inaccessible pins butthe test of the whole IC that cannot becarried out.

These restrictions can be evaded by using Cocheck II as a supplementarytest method to the analog ICT, howeverat the cost of a somewhat lower faultdetection rate than with digital ICT.

Test method

Cocheck II verifies the existence of aconductive connection between an IC

pin and the board with the aid of amagnetic field generated by a smallcurrent injected in the IC pin (FIG 1).Two magnetoresistive sensors abovethe IC detect the field components in Xand Y direction. By analyzing the totalmagnetic field vector in amplitude and direction, the characteristic of theIC connection on the board can be determined and interference caused by current in adjacent tracks or by me-chanical spread can be considerablyreduced. Such small injected currentspractically always flow via parasiticcomponents in the IC, eg protectivediodes, to the supply pins or other ICpins. The current does not depend onthe function of the IC but solely on theinput-output assignment and the tech-nology, which makes program genera-tion much easier.

The test principle employed in an in-circuit test system is shown in FIG 2. Thecurrent injected into a node via the bedof nails may be distributed to severalICs. Since a separate sensor is allo-cated to each IC, the current flowingthrough a specific pin is detected, sothat a fault can unambiguously be assigned to the IC pin rather than just tothe node. Sensor 1 can detect a currentflow, whereas sensor 2 does not see thecurrent injected into IC 2, which has anunsoldered pin and is at the same bus

node. The switching matrix allows stimulation at each node, the sensormultiplexer selects a specific sensor and routes the boosted signals to theevaluation electronics.

The continuity check is suitable both foranalog and digital ICs, the fault de-tection probability being independentof the internal function of the IC. The following faults can be detected:

• broken tracks,• non-connected IC pins (soldering

defects), also for bus ICs,• missing supply and ground pins,• missing ICs,• ICs with wrong polarity,• ICs using other technologies (eg TTL

instead of CMOS),• incorrect insertion (eg flipflop 7474

instead of gate 7400) can howeveronly be detected under favourableconditions.

The test does not check the function of an IC. Moreover, there is a certainsusceptibility to manufacturing spreads.Since unspecified, parasitic character-istics are used for the measurement, theresults may differ if the component supplier is changed. Though in somecases such a change may be desirable,this can however lead to unwantedpseudo faults.

Application notes

Low-cost continuity check in board testingusing Cocheck II

FIG 1Measurement of

current flow direction by means

of magnetic field

Generator

Induced magnetic field

Sensor

HxCurrentHy


Cocheck II analyzes the current in amplitude and direction. Techno-logical (different manufacturers) andmechanical spreads (eg uncertain dis-tance of the sensor from the substratedue to different thickness of the casingor slanted position) can be taken intoaccount by wider tolerances. This affords a reliable threshold margin forthe pass/fail decision. In particular in-correct insertions are often recognizedby the drastic change in the currentflow direction, since the current flows toanother pin while the magnitude is stillwithin tolerance.

Cocheck II is especially suitable for the diagnosis of contacting faults onbuses since in contrast to ICC (IC check[2]) diagnosis is possible at the IC pinlevel and not only at node level. Thismeans however a greater hardwareoutlay with a sensor required for eachIC. In many cases it is sufficient to pro-vide sensors only for the few complex,high-pincount ICs with fine pitch.

Operation

Program generation is semi-automaticwith the interactive test generator of thetester. The nodes are entered for eachIC. The test generator automaticallylearns the optimum stimuli and toler-ances and generates a nominal dataset for each IC pin. In the subsequentdebugging phase the values are veri-fied on different samples and the toler-

ances widened, if necessary. After thedebugging phase a complete programis available which can be added to thein-circuit test program. The convenientuser interface with automatic learning,comparison of measured with nominalvalues, the independent selection of parameters for each pin and the analysis of the magnetic field in mag-nitude and direction are essential criteria in fault detection.

Fixtures

Commercial bed-of-nails fixtures, egvacuum fixtures, can be used. The sensors are soldered to nails above orbelow the ICs. These nails are insertedand wired as usual. For components inserted on the solder side the movingplate has to be cut out. For ICs insertedon the components side, the fixture isprovided with a cover on which sensorsare mounted for each IC to be tested.After closing the cover, the spring-loaded sensors exert pressure on theICs such that bad soldering joints will not become closed by excessivepressure.

Cocheck II uses extremely low-costand reusable sensors which are independent of the IC design.

Economy

Cocheck II offers a budget-priced wayof testing the insertion of digital and

analog ICs on an analog in-circuit tester involving a single test module andslight adaptation of the fixture. Wheredigital testing has already been imple-mented, the adaptation costs and times can be reduced by omitting thegeneration of a model. With a stan-dard, low-cost sensor for all ICs, fixturecosts can be kept low.

Dr. Lothar Tschimpke

REFERENCES

[1] Tschimpke, L.: Test Workstation TSA for test-ing in electronics production and service.News from Rohde & Schwarz (1991) No. 132, pp 4–7

[2] Tschimpke, L.; Huber, J.: In-circuit-Test: Fehler-suche auf anderen Wegen. Elektronik (1993)No. 22, pp 102 –107

[3] Tschimpke, L.: LaserVision System LV1 – Op-tical insertion testing combined with classicboard test. News from Rohde & Schwarz(1995) No. 150, pp 10 –12

[4] Tschimpke, L.; Kundinger, K.: Universal TestSystem TSU – Versatile test platform for pro-duction and service of electronic modules.News from Rohde & Schwarz (1995) No. 150, pp 13 –15


Application notes

FIG 2Test setup and sensor selection

Multiplexer

Sensor 1Sensitivity

IC 1

Sensorsupply

Eval-uation

Amplitude

Direction Det

ecto

r

Sensor 2

IC 2

A

C

Current

Fault


Digital signal processing allows newtechnical features to be implemented in the field of audio, like for instance reduction of the stored or transmittedaudio data by utilizing the masking effects of the ear (MPEG). To achievethe desired perception, signals can bemodified accordingly with the aid ofdigital signal processing. This may beobtained for instance with effect pro-cessors and declickers in the studio as well as with intelligent hearing aids,in which the gain is varied either fre-quency-selectively or depending on thetype of signal.

These systems, whose characteristicsare mainly determined by dynamic processes, evade validation by con-ventional measurements since the latternormally use stationary, ie time-invari-ant test signals. Such stationary test signals however do not activate the dynamic characteristics, so that faultsupon a status change of the deviceunder test are not detected. For remedy,there are two possible solutions:

1. Development of a special test signaland associated test method for acertain dynamic characteristic.

2. A test method that is independentof the type of signal and able tomeasure the desired parameter withpractically all test stimuli.

Coherence analysis belongs to the second group. With this method thecross-correlation between input andoutput signal of the DUT is formed and divided by the relevant FFTs (fastFourier transforms) of the input and output signals; for all frequency valuesonly the magnitude but not the phase is considered. The coherence γ2 is calculated according to the followingformula:

γ2 =|channel1 x channel2|

|FFT(channel1)|x|FFT(channel2)|

If this calculation is carried out just oncefor any type of input signal, γ2 will be1 because of magnitude computation.This means that the average has to betaken over several successive measure-ments; the cross-correlation in the numerator is however averaged priorto computing the magnitude, whereasthe normalization in the denominator is made thereafter. If the phase of a certain frequency line between inputand output signal is constant in eachmeasurement, the terms in the nomi-nator will be summed. If however thephase is arbitrary (eg due to super-imposed noise), the terms are averagedas follows:

|Σchannel1 x channel2|γ2=

n.

Σ|FFT(channel1)|xΣ|FFT(channel2)|n n

The following characteristics are thusobtained for γ2:

• γ2 is a function of frequency, the resolution of which depends on thesize of both the FFT and the cross-correlation.

• γ2 is always ≤1, since the nominatorcan never become greater than thedenominator.

• If statistically the output signal is in-dependent of the input signal, cross-correlation averaging approacheszero.

• If statistically the output signal is dependent on the input signal (nosuperimposed noise), the individualcross-correlation components will be superimposed on each other at a certain frequency as a result of averaging. It should be noted thatthis also holds true for the time-vari-ant gain of the DUT, the frequencyresponse of the DUT being again irrelevant; and γ2 = 1 in this case.

γ2 is also a measure of the transmissionfidelity, ie how far the output signal of a DUT is determined by the input signal and how much it is affected by external influences (noise, etc). Coherence analysis is independent ofthe test signal, and merely the activa-tion of the frequency ranges of interestis necessary. This means that voice,voice-simulating noise, music or broad-band noise can be used. It is of courseadvisable to use signals that are criticalfor the DUT.

As a spinoff of the above, the transferfunction of the DUT is calculated as follows:

Σ|FFT(channel1)||H(f)|= n .

Σ|FFT(channel2)|n

Coherence analysis finds applicationwherever the gain is varied dependingon the signal. It can also be used toprove band clipping or gaps in a fre-quency range. In the frequency gaps,the causal connection between inputand output signal is no longer givenand the coherence value decreases. A practical application example of coherence analysis is in hearing aidmeasurements. The test setup with

Application notes

Coherence analysis in audio technology

FIG 1 Measurement of coherence and transferfunction on hearing aid using Audio AnalyzerUPL Photo 42 642


Audio Analyzer UPD or UPL [1; 2]shown in FIG 1 is used for this purpose.A multitone signal whose frequencyspectrum is appropriate for the fre-quency resolution of the analysis is chosen as the generator signal. Equal-ization of the frequency components tocompensate for the frequency responseof the test chamber can simply be ef-fected by connecting the equalizer integrated in UPD/UPL to the generatoroutput, which then directly feeds theloudspeaker in the test chamber. Thereference microphone picks up the in-put signal of the hearing aid. The outputsignal is detected via a 2-cm3 couplerin line with IEC126 or an ear simulatorin line with IEC118 and IEC711 suit-able for the adaptation of a calibratedstandard microphone.

Analyzer UPD/UPL is set to two-channel measurement by selecting the

COHERENCE function. An appropriatesetting is for instance 2048 testpoints in FFT and an averaging depth of 30.Upon completion of the measurement,the transfer and coherence characteris-tics shown in FIG 2 are obtained.

The measurement described will bespecified in the future ANSI S3.42 and

IEC draft TC29 standards. Due to theversatile design of Audio AnalyzersUPD and UPL this measurement can bemade with all models of any serial number without any hardware mod-ifications. All that is required for UPL is software option UPL-B6. For UPD, coherence analysis is included in thebasic software from version 3.0.

Wolfgang Kufer

REFERENCES

[1] Kernchen, W.: Audio Analyzer UPD gener-ates and measures analog and digital audiosignals. News from Rohde & Schwarz(1992) No. 139, pp 13 –15

[2] Kernchen, W.: Audio Analyzer UPL – Audioanalysis today and tomorrow. News fromRohde & Schwarz (1996) No. 151, pp 4–6


Application notes

FIG 2 Printout of transfer function and coherencemeasurement

Long-term monitoring of sound-broadcast and TV transmitters

The core of Transmitter MonitoringSystem SMSA is Spectrum Monitor-ing Software ARGUS, Test ReceiverESVN40 (9 kHz to 2.75 GHz) orESVN20 (20 MHz to 1 GHz) and

Like equivalent organizations in othercountries, German broadcasting andmedia companies as well as the FederalPost and Telecommunications Office (BAPT) have the duty to continuouslymonitor transmitter parameters*. Trans-mitter Monitoring System SMSA fromRohde & Schwarz is a simple and cost-effective solution to perform thistask. It not only monitors the limits forfield strength, modulation, frequencyoffset and bandwidth but also trans-mitter breakdowns. Any deviation fromnominal is immediately signalled as an alarm message at the test site or signalled to remote receiving stations.

* Seidl, W.D.: Spectrum monitoring the ITU way.News from Rohde & Schwarz (1997) No. 153,pp 26 –27 FIG 1 Configuration of Transmitter Monitoring System SMSA

Modem

Modem

Modem

Telephonenetwork

Modem

Antenna selector switch

Relais Switch Unit

System ProcessController

Test Receiver ESVN40 9 kHz…2750 MHz

TV antenna470 to 860 MHz

TV antenna174 to 202 MHz

FM antenna87.5 to 108 MHz

10 kHzto 80 MHz

20 to 1300 MHzvertical

20 to 500 MHzhorizontal

500 to 1300 MHzhorizontal

Cabling

a process controller (FIG 1). For mea-suring vertically polarized signals in thefrequency range 20 MHz to 1 GHz,Antenna HE309 is directly connectedto Test Receiver ESVN20. If several an-


tennas are used (extended frequencyrange, vertical or horizontal polar-ization, omnidirectional or directional,active or passive), they (FIG 2) arechanged over by means of an antennaselector switch. Alarm messages aretransmitted via the public phone net-work if several receiving stations haveto be informed or if the test station is un-attended. Up to three alarm controllerscan receive information about devia-tions of the transmitter parameters.

For monitoring to be of real value theparameters of all the channels shouldbe measured simultaneously in theshortest possible time. Transmitter Monitoring System SMSA monitors thefield strength, modulation (AM and FM)and frequency offset of, for example,ten TV and 40 sound broadcastingchannels at a repetition rate of 3 s (with-out antenna switchover) or 20 s (withswitchover between eleven different antennas).

With Spectrum Monitoring SoftwareARGUS the user can define individuallimits for the various parameters ofeach transmit channel. If any of theselimits is violated, an alarm message willbe issued immediately:

• For the field strength, there is a tol-erance range, ie if the field strengthfalls below the lower limit, a trans-mitter breakdown will be signalled.If the upper limit is exceeded, an impermissible transmit power will be indicated.

• This is also valid for the frequencyoffset. A deviation from the permis-sible tolerance range is signalled aserroneous operation.

• For modulation and bandwidth,there are only upper limits.

To avoid alarms being triggered everytime a stray value occurs, measure-ments have to lie outside the tolerancerange several times and in a sequence.The number of stray values actually triggering an alarm can be set by theuser between one and 1000: a reason-able value would be three. An OK mes-sage will be signalled if the limit valuesare adhered to again (eg following atemporary transmitter breakdown).

This procedure will be illustrated byway of an example: the field strengthon a channel is measured every 5 s.The number of tolerated limit violationsbefore an alarm is triggered shall be three. The results together with anupper and lower limit line are dis-played versus time (FIG 3). At test point5 (after 20 s) an alarm will not be triggered since the upper limit has onlybeen violated once. At test point 11 (after 50 s), the upper limit is violatedagain. An alarm message however willnot be triggered until test point 13 (after60 s) is reached since the number of tolerated limit violations was defined as three (3). The alarm message issuedrelates to the status of test point 11, iewhen the problem occurred for the firsttime. From test point 18 (after 85 s) the measured values are again withintolerance. The OK message will be

sent from test point 20 (after 95 s) since three alarm messages have again been attained. The data of theOK message refer to the field strengthat test point 18.

Alarm messages are directly output atthe process controller or will be sent viaa modem. If only one alarm messageoccurs, it will be sent to one or severalalarm controllers via the public phonenetwork. The messages will be dis-played there as shown in FIG 3 or maybe printed out (for test report see bluefield).

The status information reveals whethera measured value is above the upperlimit, below the lower limit or againwithin tolerance with the latter being in-dicated by the OK message. Moreover,an alarm can also trigger further ac-tions in the test system: 1. an additionalmeasurement will be carried out andlogged (eg bandwidth measurement),2. a signal tone will be generated (forunattended stations).

Application notes

Transmitter Monitoring System SMSAthus reliably fulfills tasks required for thecontinuous monitoring of transmitters. Itsupports the responsible bodies and organizations to eliminate the problemsbefore the first complaints from listenersor viewers come through.

Jörg Pfitzner; Wolf D. Seidl


Message Date Time Frequency Limit Measured Test Status Comment from value parameter frequency list

Alarm 14.03.97 12:00:50 98.500000 MHz 40 dBµV/m 44 dBµV/m Level High Bayern 3

Alarm 14.03.97 12:01:25 98.500000 MHz 40 dBµV/m 31 dBµV/m Level OK Bayern 3

FIG 3 Results curve for field strength (blue); limit lines in red

FIG 2An antenna system of Transmitter Monitoring SystemSMSAPhoto: Pfitzner

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 s0

5

10

15

20

25

30

35

40

45

50

Fiel

d str

engt

h

dBµV/m

Time


The two software products StreamCombiner (option for MPEG2 Genera-tor DVG) and Stream Explorer (optionfor MPEG2 Measurement DecoderDVMD) allow very flexible handling of MPEG2 transport streams. Variationand analysis of data streams is possibledown to bit level and overview is guaranteed thanks to the user-friendlyWindows interface.

MPEG2 Generator DVG* is especiallypopular because of its ease of oper-ation and applications: you simplyswitch it on, select the desired transportstream, and the MPEG2 signal ispromptly available. All this is possiblewith a single unit without a PC, encoderor multiplexer being required. The trans-port streams supplied by DVG coverthe most common types of application.With the Stream Combiner software,users with individual applications nowhave a tool to generate their own spe-cific transport streams by combiningelementary streams and by configuringsystem parameters (FIG). The softwareoffers the following functions:• Compilation of new transport

streams from the supplied elemen-tary stream library; all the elemen-tary streams are coded in a specialway such that they can be multi-plexed to an endless data flow inDVG.

• Insertion of user-specific elementarystreams (MPEG2-coded data files).

• Free creation of MPEG2 system parameters (ie selecting PIDs, editingPAT and PMT, setting the repetitionrates of tables).

• Selection and edition of service in-formation including all DVB tablesand their descriptors (eg programname and supplier).

• Generation of specific errors or non-conformal states in the transportstream.

Windows software Stream Explorersupplements the functions of MPEG2Measurement Decoder DVMD*. Whilethe concept of DVMD is tailored to therealtime analysis of MPEG2 transportstreams in compliance with MPEG2and DVB, Stream Explorer is intendedfor the detailed analysis of the struc-ture, contents and system parameters oftransport streams. To this effect, it eval-uates transport stream data providedby DVMD to the PC. A great variety of data filtering as well as access to preprocessed data stored in DVMDprovide fast and clear results. The re-sults shown in graphics or tables relateto the MPEG2 transport stream appliedto DVMD.

The Stream Explorer functions are con-centrated on the following three areas:• Representation and interpretation

of stream contents; forms of rep-resentation are the tree structure forthe whole transport stream and thehexadecimal display of individualtransport stream packages. The detailed but clear representation forall syntax elements of a transportstream is of central interest.

• Trigger on error; Stream Explorermakes use of this function supportedby DVMD. If a trigger event occursin the applied transport stream, thedata in the area of the irregularitywill be stored in the measurementdecoder and sent to Stream Explorerfor evaluation.

• Visualization of system parametersof transport stream; in addition tothe structure and contents, StreamExplorer also displays the system parameters of the transport streamby means of the bar and trace dia-grams. Data rates of the elementarystreams or the jitter of the time refer-ences are typical examples. More-over, it is possible to display andmonitor the buffer fullness of thesystem target decoder as defined inMPEG2.

Besides these functions Stream Explorersupports the full remote control ofDVMD. DVMD, originally conceivedfor monitoring tasks, is upgraded byStream Explorer to a versatile instru-ment for the comprehensive and de-tailed analysis of MPEG2 transportstreams.

Michael Fischbacher; Werner Rohde


Software

PC software for MPEG2 dream team DVG/DVMD

* Fischbacher, M.; Weigold, H.: MPEG2 Gener-ator DVG and MPEG2 Measurement DecoderDVMD – Test equipment for digital TV in line withMPEG2. News from Rohde & Schwarz (1996)No. 152, pp 20 –23

Editing network information tablewith Stream Combiner software


3.2 Minimum shift keying and Gaussian minimum shift keying

3.2.1 Mathematical derivation of MSK

When it formulated the GSM standard,the standards committee chose a differ-ent approach and stipulated anglemodulation with a constant envelope ofthe RF signal for digital networks. Thismeans that the length of the vector rep-resenting the RF signal does not changeas it turns through an angle of ∆ϕ fromϕ(t1) to ϕ(t2) over a time interval equalto the bit duration. The end of the vector must, therefore, describe the arcof a circle with an angular speed of

. After turning through this

angle, during which a symbol is trans-mitted, the vector does not remain stationary in the position it has reachedbut continues to turn in the same direc-tion, so repeating the signal that hasbeen transmitted, or turns in the oppo-site direction, so sending the oppositeof the transmitted bit.

The phase change of the RF signal withrespect to the arbitrary zero phase ofthe unmodulated carrier is associatedwith a frequency change of ∆f. The instantaneous frequency and the fre-quency deviation can be calculatedfrom the first derivative of the carrierphase, in other words from the deriva-tive of the argument of the cosine func-tion describing the carrier.

If the phase change ∆ϕ that occurs overthe duration of a bit is expressed as a multiple h of π, h being referred to as the modulation index, the followingrelations are obtained:

Φ(t) = 2πfct + ϕ(t) 2πh= 2πfct + ϕ0 ± ——– t,2Tbit

dΦ(t) dϕ(t)—–—— = 2πfc +[——–—]dt dt= 2πfc ± 2π∆f

2πh= 2πfc ± —–—;2Tbit

h∆f = ———;2Tbit

2πhϕ(t) = ϕ0 ± ———t; ∆ϕ = hπ (19)2Tbit

The signals representing the symbols 0and 1 can then be expressed as:

hs1(t) = A · cos[2π[fc + ———]t]2Tbit

= A · cos(2π(fc + ∆f )t)

andhs2(t) = A · cos[2π[fc – ———]t]2Tbit

= A · cos(2π(fc – ∆f )t) (20)

These equations describe frequencykeying (see equation 12). Because thephase changes continuously, this type of modulation is referred to as con-tinuous phase frequency-shift keying (CPFSK). FIG 10 shows the correlationsbetween the data sequence, currentphase and current frequency. The trellisdiagram which shows the possiblephase transitions also explains why a CPFSK modulator has a memory. It is easy to see how the current phase depends on previous states.

Equation 13 gives the following ex-pression for the correlation factor ofthe two signals s1(t) and s2(t):

sin(π · h) sin(2πfc Tbit )ρ = —––—–—— – —–—–——–—— (21)π · h 2πfc Tbit

If fc >>1/Tbit, the second term can be neglected. Uncorrelated signals (ρ = 0) are obtained when h = k · 0.5where k ∈ 1, 2, 3, …; h = 0.5 is therefore the smallest modulation index for which the two signals are uncorrelated. FSK with h = 0.5 and

is therefore also

referred to as minimum shift keying (MSK). TABLE 3 summarizes the mainparameters for this type of modulationonce more.

3.2.2 Implementing MSK

The simplest way of producing an MSKsignal would be to convert the data sequence a(n) into a bipolar NRZ signal which is then used to control aVCO (FIG 11). This approach is in factadopted for, say, cordless phoneswhere the specifications for the fre-quency and angle accuracy of the

Refresher topic

Digital modulation and mobile radio (V)

dϕ ∆ϕ––– = –––– dt Tbit

1 1∆ f = —––— = — fbit4Tbit 4

TABLE 3 MSK parameters

Modulation Frequency Phase shift over Correlation Euclideanindex h deviation ∆ f bit duration Tbit factor ρ distance D

1 1 π0.5 —––— = — fbit — = 90° 0 √—––—2Ebit

4 Tbit 4 2

FIG 10Relationships between data signal,frequency and phase for minimumshift keying

0

1

0 1 2 3 4 5 6 7 8 9 10 11 12

t

f+nf

π2

2π2

π2

3π2

0

tf-nf

ϕ0=0

n-Tbit

ϕ (t)

3π22π2π2

3π2

2π2


modulated signal do not have to be sostringent. However, the GSM specifi-cations for the maximum frequency andangle error during a burst are so tightthat a VCO would be incapable ofmeeting them. An I/Q modulator givesbetter results under these restraints. Be-fore analyzing a modulator of this kind,it will be useful to briefly review the I/Qnotation used for modulated RF carriersonce more.

s(t) = A · cos[2πfct + ϕ(t)]= A · [cos(ϕ(t)) · cos(2πfct)

+ sin(ϕ(t)) · (–sin(2πfct))] (22)

The RF signal has two mutually or-thogonal components cos(2πft) and –sin(2πft) = cos(2πft + π/2) which aremultiplied by the functions cosϕ(t) andsinϕ(t) by means of, say, two double-balanced mixers. The angle ϕ(t) canbe obtained from equation 19 and isgiven below:

ϕ(t) = ϕ(nTbit) ± 0.5π/Tbit · t* (23)with 0 < t* < Tbit

In practise, the modulated carrier canbe obtained in the following way:1. Obtain the two mutually orthogonal

carrier components l(t) = cos(2πft)and Q(t) = –sin(2πft).

2. Multiply the I component withcosϕ(t) and the Q component withsinϕ(t).

3. Add the two components.

The next problem is the generation ofthe modulating signals cosϕ(t) andsinϕ(t). This cannot be done with classicanalog methods, the signals have to becalculated digitally using equation 23for the time nTbit < t* < (n +1)Tbit, thepolarity of the fraction determiningwhether a 1 or a 0 is sent.

The following approach is used:1. Start with an initial phase. If ϕ (0)

= 0 is selected, equation 26 getsless complex: sin(ϕ(nTbit)) becomes0, cos (ϕ(nTbit)) becomes ±1.

2. Calculate ϕ(t) (for example by usinga digital accumulator).

3. Calculate the functions of time cI(t)and cQ(t) from tables.

4. Calculate the phase ϕ(nTbit), (lastaccumulator value in 2).

5. Go to 2.

FIG 12 shows this procedure for eightconsecutive bits; FIG 13 shows how themodulator operates. The bipolar NRZsignal is proportional to the instanta-neous output frequency fc ±∆ f of the

Refresher topic

modulator. In the accumulator it is inte-grated to give a signal that is propor-tional to the instantaneous phase of the modulated carrier. Tables for sinϕ(t)and cosϕ(t) provide the signals cI(t) andcQ(t) in digital form. After D/A conver-sion and analog filtering by a lowpass,these signals are fed to the modulatorsat whose RF inputs the orthogonal components of the carrier have beenapplied. The two modulated carriercomponents are added in a power summer to give the output signal. If youconsider the I/Q modulator from thepoint where the bipolar NRZ signal is fed into the RF output, it acts as a frequency modulator or a VCO.

To be continued. Peter Hatzold

If the data sequence a(n) is mapped onto the data function

c(t) = c(nTbit + t*)

+1 for a(n + 1) = “1“= H–1 for a(n + 1) = “0“ (24)

(23) can be rearranged to give

0.5 · πϕ(t) = ϕ(nTbit) + c(t) · —––——t* (25)Tbit

This yields:

πcI(t) = cos(ϕ(nTbit)) · cos[—–—– t*]2 Tbit

π– c(t) · sin(ϕ(nTbit)) · sin[—–—– t*]2 Tbit

andπcQ(t) = sin(ϕ(nTbit)) · cos[—–—– t*]2 Tbit

π+ c(t) · cos(ϕ(nTbit)) · sin[—–—–t*] (26)2 Tbit

FIG 11 Generating minimum shift keying with VCO

FIG 13 I/Q modulator

for MSK

FIG 12 Modulation signals and I/Q signals forMSK

VCO

1

0t

Baseband signal

f0+nf

t

Output frequency

π2

t

Phase of MSK signal

f0-nf

f0

π2

ϕ(t)

f(t)

01 0 0 01 1 1c(t)

ϕ(t)

cl(t)

cQ(t)

D

A

cos(2πft)

D

A

-sin(2πft)

cos(2πft+ϕ(t))Calculation

of sinϕ and

cosϕ

Calculationof phaseangle ϕ

ϕ(t)

f(t)


With shortwave propagation over thesea, groundwave communications canbe established over considerably longdistances; with ship-to-ship communi-cations on the high seas it may even be possible to cover several hundredsof kilometers, depending on the trans-mitter power and bandwidth. In coastalareas and for ship-to-land communica-tions, the groundwave coverage rangebecomes distinctly shorter. When thesignal crosses the sea-land interfaceseveral times, there is a dramatic dropin field strength. The shadow effects behind islands are well-known and can hardly be avoided where verticallypolarized waves are radiated to covershort and medium distances exclusivelyby means of groundwaves.

The solution to this problem is high-angle radiation via the ionosphere(NVIS). Using appropriate transmittingand receiving antennas and selecting a suitable frequency, any distance can becovered [1]. Due to the limited spaceavailable onboard ships, suitable high-

angle antennas are usually unbalancedwire antennas, loop antennas and bal-anced dipoles.

Unbalanced wire antennas predomi-nantly used in the past are usually fedfrom a slanting feed line which in addi-tion to the desired horizontally polar-ized wave also generates a verticallypolarized wave. This however entails anumber of disadvantages: part of thetransmitter power is not utilized for theintended transmission. Moreover, thereis a zone of confusion in which ground-wave and skywave arrive with approx-imately the same field strength; recep-tion is impaired through interference ofthese two types of waves. Position andsize of this interference zone dependson place and time. Finally, the verticallypolarized field causes stronger inter-ference to shipborne systems than thehorizontally polarized field. In view ofthe difficult EMC situation onboardships, vertically polarized emissionsshould therefore be avoided whereverpossible.

In addition to high-angle radiation,loop antennas also radiate verticallypolarized signals so that the disad-vantages are the same as with the unbalanced wire antennas. Moreover,normal-size loop antennas have low efficiency with the result that less poweris radiated, especially at the low fre-quencies occurring at night. Althoughthis effect improves the EMC conditions– where there is little radiation there are also less EMC problems -– it is obviously at the expense of radio linkreliability.

1- kW horizontal balanced dipoleshave already proven themselves on-board larger vessels. With HX002M1 (FIG) Rohde & Schwarz is now offeringanother HF dipole with integrated tuning unit, which thanks to its length of only 5 m and low weight is suitable

for use on medium-sized and smallships. The dipole is designed for atransmitter power of 150 W, which ismainly used on such ships and whichcalls for a high-efficiency antenna.

Through concentration of the availablepower on high-angle radiation, radiotransmission is considerably improvedby HX002M1 as compared to systemsusing the other types of antennas men-tioned above. Especially the compar-ison with loop antennas shows a dis-tinctly higher link reliability, above allduring the critical night time. Moreover,horizontal polarization of the radiatedwaves improves the EMC situation onboard. Like the 1-kW dipoles,HX002M1 features a robust and extremely corrosion-resistant design toprotect it against the harsh environ-mental conditions onboard ships;shock, vibration and salt spray tests inline with relevant specifications haveproven the suitability of HX002M1 foruse on ships.

For shortwave radio stations on land,the tried and tested balanced HF Dipoles HX002A1 for 150 W [2] andHX002 for 1 kW with the same qualityfeatures are available.

Axel Stark

REFERENCES

[1] Stark, A.: Propagation of electromagneticwaves (R&S reprint)

[2] Demmel, F.; Klein, A.: 150-W HF DipoleHX002A1 – The antenna for reliable short-wave links. News from Rohde & Schwarz(1996) No. 150, pp 29–31


Panorama

Better HF radiocommunications for smaller vesselswith Marine Dipole HX002M1

150-W Marine Dipole HX002M1 (1.5 to 30 MHz) features extremely low weight, small size and robust design. Photo 42 826/1


An essential parameter for describingthe linearity of an electronic circuit is the compression point (CMP) in addition to the intermodulation points(IP2 and IP3). Measurement of the 1-dBcompression point, for instance, used to be a complex procedure until now.First, the small-signal gain of the deviceunder test has to be determined foreach frequency point. Then the inputpower is successively increased andthe output power checked at the sametime for linear increase with the inputpower. This has to be continued untilthe power reaches a value at which themeasured gain, ie the ratio betweenoutput and input power, is 1 dB lowerthan the small-signal gain. The 1-dBcompression point has thus been foundfor this frequency point and can be determined in the same way for thenext one. Manual performance of thismeasurement is a laborious task, takesa lot of time and is liable to errors.

The nonlinear measurements option (ZVR-B5) available for the vector network analyzers (FIG 1) of the ZVRfamily [1; 2] automatically performs the complete measurement procedure

with high speed simply at a keystroke.Measurement of the compression pointis activated via the mode menu of ZVR.Enhancement label CMP lights up to the right of the diagram. Generally, thex-dB compression point can now auto-matically be determined, with any value between 0.1 and 10 dB being selectable for x. In addition to the compression point referred to the output, the compression point referredto the input can be indicated just as easily. The result obtained is a tracenearly in realtime (3 s for 201 frequencypoints) similar to that of an ordinarypower or S-parameter measurement. Inthis case however the trace is a contin-uously updated display of the selectedcompression point versus frequencywhich allows fast alignments in the laboratory or in production.

FIG 2 shows typical measurement results obtained for a commercial typeof integrated amplifier. The red tracerepresents the 1-dB compression pointof the amplifier referred to the output,measured in a frequency range from50 MHz to 1.6 GHz and found to beabout 15 dBm. The small-signal gain at an input power of –36 dBm was alsomeasured. The blue trace shows thatthe small-signal gain drops from about32 dB at low frequencies to 21 dB at 1 GHz (marker 2). Furthermore, the

compression point referred to the inputwas determined and shown as a greentrace. As expected from theory, the frequency characteristic is a rising func-tion and approximately inverse to thesmall-signal gain.

Using an external source, the 2nd- and3rd-order intermodulation points can also be measured with the aid of optionZVR-B5 in a similarly easy and fastway.

Dr. Olaf Ostwald

REFERENCES

[1] Ostwald, O.; Evers, C.: Vector Network Analyzer Family ZVR – To the heart of thechart. News from Rohde & Schwarz (1996)No. 150, pp 6–9

[2] Danzeisen, K.: Frequency-selective measure-ment and display of frequency-dependenttest parameters. News from Rohde &Schwarz (1996) No. 152, p 47


Panorama

New option for fast compression-point measurementswith Vector Network Analyzer ZVR

FIG 2 Automatic compression-point measure-ments with Vector Network Analyzer ZVR andnonlinear measurements option. Test results of integrated amplifier: small-signal gain (blue), 1-dB compression point at output (red) and 1-dBcompression point at input (green)

FIG 1 Vector Network Analyzer ZVR, the all-rounder for network analysis Photo 42 255/2


The cable headend installed by Rohde& Schwarz in Vaduz for the Liechten-steinische Kabelgesellschaft is now supplying the whole country with sound and TV programs. Since recep-tion is extremely difficult due to the geographics of Liechtenstein, severalreceiving stations had to be set up integrating the control system into themain station. More than 50 analog TVprograms, three digital TV packages,31 VHF FM programs, a country-spe-cific channel for the transmission of parliament sittings using a fixed camera, and a local service channel for district council sittings are fed intothe network.

The cable headend is equipped withcomponents of CATV Headend SystemCT200*. Thanks to the modular design

of this system, the complete equipmentcan be accommodated in only eight19“ racks (FIG 1) and there is stillenough room left for extensions. Everyrack is controlled and monitored by a separate controller. Different activeand passive combiners allow variousmodule combinations.

Troublefree operation of the CATV network is indispensable – not only because of the competition from othersatellite operators – and so the reliabil-ity of the CT200 system has been giventop priority. CT200 is the only systemworldwide which monitors the moduleunder test in every detail. Each module has a microprocessor allowing module-to-controller communication viaa system-internal bus. The micropro-cessor not only carries out controlling, italso provides test data and thus makeselaborate test routines for certain applications unnecessary. In practice,this means that all the changes are registered and that response times areextremely short.

The continuous monitoring of certaintolerance ranges means that a kind ofpermanent check-up is made. System-relevant parameters (eg level, frequency

drift) can be defined as default valuesby the user; the processor of the deviceresponds with a corresponding mes-sage. All the drifts are logged over acertain period of time and, if a more accurate analysis is required, can bedisplayed and printed out any time. Allparameters are logged continuously.

Operational reliability is complementedby a n+1 standby system which is currently the fastest, most effective andattractively priced switchover systemworldwide. The controller decidesabout switchover in a couple of sec-onds without any measurements beingrequired. Switchover is possible at different signal levels and depends on the requirements and philosophy ofthe cable network operator.

The interactive Windows user interfaceof the system software can be managedvery easily by anyone especially as thecomplete system is displayed graphi-cally. By clicking the graphic elementsusing the mouse the user can go deep-down into the system and modify any setting or parameter whenever required. A password is of course required to access the system and allaccesses are logged.

The main station of the cable headendsystem in Vaduz controls and monitorsthe two receiving stations Sücka andGaflei that are difficult to access withcable modems via the broadband coaxial cable (FIG 2). The advantagesof this solution are evident: high trans-mission rates, no point-to-point lines,low costs, permanent connectionbetween the CPU in the main stationand the external stations.

Special frequency-relevant measureswere required because the receivingstations (as seen from the headend) arelocated one behind the other and thewhole data transfer from Sücka has to

Panorama

CATV Headend System CT200 suppliesLiechtenstein with sound-broadcast programs

FIG 1 View of cable headend of Liechten-steinische Grossgemeinschaftsantennenanlage(LGGA) in Vaduz Photo 42 827/1

* Schönberger, P.; Sturm, P.; Scheide, R.: CATVHeadend System CT200 – CATV signal process-ing intelligent, compact, versatile. News fromRohde & Schwarz (1995) No. 148, pp 23–25


The use of surface-mounted devices (SMDs) in electronic circuits has in-creased rapidly in the past few years. In some areas, their propor-tion in the circuitry makes up over90%.

While in production soldering methodsused are aimed at high throughputs perunit time, the requirements for serviceare of a different nature. Devices haveto be soldered and desoldered withoutaffecting the highly sensitive board

circuitry. When conventional solderingtechniques are used, devices andboards are often damaged. Rohde &Schwarz Cologne has developed a soldering workstation particularly designed for servicing applications: Repair System SMD-RS11 (FIG). Thissystem assists the user in complyingwith the standards required by quality management, for instance the stringentMIL standards. Thanks to the wealth of experience gathered during the in-house use of the system, it can be updated to match new requirements.The user can be assured that the described technique is an optimal system solution. To date, SMD-RS11 isbeing used successfully by renownedcompanies and authorities worldwide.

Rainer Ewert


Panorama

be organized via Gaflei. But CATVHeadend System CT200 from Rohde & Schwarz solved all the problems connected with the difficult receivingconditions, continuous monitoring and(n+1) standby and a large number of programs intelligently, easily and economically.

Reinhard Scheide


Receivingstation

Sücka

Mainstation

Vaduz

Receivingstation

Gaflei

Inputcoupler

Inputcoupler

Frequencycoupler

Frequencycoupler

Inputcoupler

Frequencycoupler

Inputcoupler

Pilotgenera-

tor

Modem

Con-troller

Con-verter

approx. 80 MHz

20 MHz

Link Link

Modem

Con-troller

Con-troller

Liechtenstein’scable network

Band-passfilter

Pilotgenera-

torModem

Con-troller

approx. 80 MHz

approx. 20 MHz

Modem

FIG 2 Block diagram of cable system in Liechtenstein

Repair System SMD-RS11 – a tool for state-of-the-art servicing of printed circuits

Soldering workstations with Repair System SMD-RS11 Photo: Willsch


Panorama

Modern naval vessels are highly com-plex systems not only with regard to the technologies involved, but also because of the permanent exchange ofinformation taking place between thesubsystems of the vessel and other vessels or land-based stations, whichmakes effective communication meansessential. The information conveyedmay include messages with contents fol-lowing a particular format or structure,free text, fax and video. Communi-cation is based on the use of suitableprotocols (eg X.400, ACP123 andACP127) via radio waves or lines. Thevolume of information communicatedtoday is often more than what an operator can be expected to handle. Effective tools are needed to gain an overview of the situation. Bearing in mind that all communication datashould in addition be archived and registered, the use of a computer-basedand program-controlled informationsystem becomes inevitable.

IMCOS from Rohde & Schwarz is asystem having the described qualities (FIG). It covers all tasks essential forcommunication: message handling,controlling external and internal trans-mission equipment, automatic or man-ual selection of transmission equipmentand of course administration of all messages in a database.

The message handling functions in-clude everything required for correctlyreceiving and sending messages aswell as editing, approving, releasing,archiving and encoding them and handling incomplete messages. It is also possible to determine certain message paths (workflows) in advance(for instance routing messages to another person in times of absence).

Controlling external and internaltransmission equipment means thatradio links optimally suited for the current situation are selected, con-figured and controlled. A number of individual functions (radio control, audio and signal matrix control, fre-quency and antenna management) areintegrated, which makes operationmuch simpler. A radio link may consistof a transceiver, a modem and an encoder. The individual components ofa radio link are interactively connectedvia the digital communications net-work. On land, the system may also be used with PABX or ISDN, ie with line connections.

The transmission equipment selectionfunction serves for choosing the trans-mission equipment that will transmit amessage optimally under time/cost aspects. For radio transmission, the frequency and antenna management

may be used for support. This systemproposes the radio link (antenna, trans-mission facility, power, etc) that is optimally suited for a particular situa-tion (time of day, user location, receiverlocation).

The database serves for storing and archiving in- and outgoing messages.Data of different classification arestored in a single database without affecting sensitive data. Different levelsof access for individual users guaranteeprotection of the data against unauthor-ized use.

Whether or not a system like this is taken up by the user depends largelyon the user interface. IMCOS hasbeen specially designed for use in military environments. All essentialfunctions have the same graphical user interface laid out according to theprinciple that “what you see is what youget”. This guarantees a brief period offamiliarization with the system. The user is supported by an integrated online manual, a comprehensive faultmessage system and macros allowingthe simplification of standard proce-dures.

Bernhard Wolf


IMCOS – a message handling and control system for naval forces

Scanner VideoI/O

IMCOSRadio ControlData Processor

IMCOS-Server-Cluster

Printer

... ...

Gateway

ESMSystem

ISDN-Gateway

.. .. .. .. ..

Datalink

Digital Tactical IntercomRATT, Encryption

CDSSystem

Ship ITSystem

NAVSystem

IMCOSRadio ControlData Processor

IMCOS-Workstation

Printer

PrinterIMCOS-Workstation

LAN / WAN(ATM / FDDI)

InterfaceUnit

External Communications(VHF, HF, LOS, SATCOM, ...)

Integrated MessageHandling and Con-trol System IMCOS.The system platformfor the applicationshown is based on workstations ofappropriate design.


Information in print

Portable Industrial Controller PSP (AMD X5(586), 133 MHz) runs under MS-Windows (3.1 or higher) or MS-DOS (6.2 or higher), is equippedwith LabWindows/CVI for measurements and drivers for almost any programming language;main memory 8 (and up to 32) Mbyte, harddisk540 Mbyte or more, disk drive, VGA graphics 640 x 480 (plus external), colour LCD 8.4’’ (select-able), numerous interfaces and options; AC andDC operation (eg for solar power).

Data sheet PD 757.2515.21 enter 154/19

Jitter and Interface Tester UPD-B22 measuresphysical parameters of the serial bit stream via theoptional AES/EBU interface of Audio AnalyzerUPD.


DAB Multiplexer DM001 is compatible with DABstandard ETS300401 and uses up to twelve audioand data channels to form ETI(NI) or optionallyETI(NA) with 2.048 Mbit/s; FIC generated frominternal/external information; option: Reed-Solo-mon module. DAB Network Adapter DY001 iscompatible with ETS300799 and converts ETI(NA)back into ETI(NI).


DAB Transmitter Family NA5... (174 to 230 MHz;250 / 500 / 1000 W) and NL50.0 (1452 to 1492 MHz; L-band; 100 / 200 / 400 W) The solid-state transmitters for terrestrial digital audiobroadcasting are economical, highly reliable andsystem-compatible (SFN, eg through linking toGPS); built-in COFDM modulator; linearity pre-corrector; built-in blowers for ambient or externalair; IEC/IEEE bus and RS-232 (RS-485) interfaces.


NICAM Coder/Modulator CT200N2 is a supple-ment to CATV System CT200 and supplies a second4PSK(QPSK)-modulated IF sound subcarrier.


Paging systems with multiprotocol capabilityACCESSNET ®-P This brochure from R & S BICKMobilfunk presents economical paging systemsfor all relevant standards.

Info PD 757.2838.21 enter 154/28

Digital Monitoring Direction Finders DDF0xM(0.3 to 3000 MHz) Among other new features, HF Antenna ADD010 (semi-mobile or stationary,elevation ≤ 50°, limited SSL) is presented.


Digital Scanning Direction Finders DDF0xS (DDF01S: 0.5 to 30 MHz, DDF06S: 0.5 to 650/1300 MHz) detect complex signals at 200 MHz/s(with 8-kHz resolution); DF error (AntennaADD051) 1° RMS; Watson-Watt and correlation;stationary and mobile use, system-compatible.


Airport Communications & DF This brochure highlights the 40 years of experience Rohde &Schwarz has gathered in ATC systems including direction finders.

Info PD 757.3111.21 enter 154/26

EMC Test & Measurement Products The Englishedition of this catalog has been revised and newlypublished.

Cat PD 757.2350.22 enter 154/27

New application notes

Measurements on GSM base stations according toRec. 11.20Appl. 1EF23_0E enter 154/29

Measurements on PCS1900 base stations accord-ing to J-STD-007Appl. 1EF24_0E enter 154/30

4-port measurements with Vector Network Ana-lyzer ZVRAppl. 1EZ25_0E enter 154/31

3-port measurements with Vector Network Ana-lyzer ZVRAppl. 1EZ26_0E enter 154/32

Frequency conversion measurements with VectorNetwork Analyzer ZVRAppl. 1EZ27_0E enter 154/33

Producing epicycloid tracesAppl. 1EZ28_0E enter 154/34

Measurement uncertainties for vector networkanalysisAppl. 1EZ29_0E enter 154/35

Automatic calibration of Vector Network AnalyzerZVRAppl. 1EZ30_0E enter 154/36

Schz


Consul General of People’s Republic of China visits R&S

The People’s Republic of Chinaopened its own consulate general inMunich at the beginning of the year,a major reason being the steadygrowth in business between Bavariaor southern Germany and Chinaand the number of people visitingthe country. Besides the usual con-sular office for visa matters and thelike, the consulate general also has atrade department. This is meant toact as a first port of call for Germanfirms and assist them in creating anddeveloping business relations withChina.

It was a sign of special esteem whenConsul General Liu Guangyao visitedRohde & Schwarz right at the start of his term in Munich. FriedrichSchwarz, who is Honorary Consul ofIceland, welcomed the guest. Therewere no language problems duringtheir meeting because the ConsulGeneral speaks fluent German. Hestudied German language and liter-ature at Beijing University and haseven translated some of HeinrichHeine’s works into Chinese.

Following a general presentation ofRohde & Schwarz and a report on its activities in China, the guest wastaken on a short tour of the com-pany to see and learn something of the various divisions. He was surprised by the wide ranging prod-uct assortment and pleased to hearof the long and good relationsbetween Rohde & Schwarz and hishomeland. An entry in the visitors’book and a toast (photo) symbolizedthe mutual wish to further developcontacts and relations between Rohde & Schwarz and China.

J. Beckmann

12th International EMC Symposium

The highly reputed EMC Symposiumin Zurich with its accompanyingtechnical show attracted some 750 participants from more than 30 countries in February of this yearto discuss the subject of electro-magnetic compatibility. Half of theparticipants were scientists come totell of all that is new in their disci-pline, while the other half were prac-ticians looking for solutions to theirproblems. The conference offeredover 100 technical contributions in the form of lectures, seminars, sessions and special events. Withsome 70 firms exhibiting, there waseven more to see than in recentyears. Rohde & Schwarz – repre-sented by the motto EMC Solutionson an attractive stand (photo) – wasagain able to present a worldpremière, the EMI Test ReceiverESCS (see page 7 in this issue). Thisdrew a lot of attention from both visitors to the show and competitorfirms. V. Janssen

Newsgrams

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Engine Exhaust Analysis workshop at Rohde & Schwarz

Leading designers of combustion engines met at the end of last year at the Rohde & Schwarz plant in Cologne. The 30 participants wereable to learn of a new measuringmethod as part of a workshop on thesubject of engine exhaust analysis.They were acquainted with Airsense500, one of the most powerful massspectrometers, a high-speed deviceoffering valuable support in the design and optimization of com-bustion engines (see News fromRohde & Schwarz No. 151).

Dr. Andreas Wasserburger of Rohde& Schwarz environmental and pro-cess measurement engineering andDr. Johannes Villinger, the designerof the mass spectrometer, presentedfascinating measurements from au-tomotive research and development.Possible uses are optimization of themixture in vehicle engines and opti-mum design of catalytic convertersfor exhaust systems. All engine designers work under extreme pres-sures in terms of competitiveness andcost. Modern measurement technol-ogy can help achieve a competitiveedge, because fast measurementsshorten the time to design and thus cut costs. The presentation ofother projects from research andprocess measurement ended with a lively roundtable, during which experience was exchanged and newpossibilities of use were discussed.This event demonstrated once againthat Rohde & Schwarz Cologne, witha constant stream of innovations, is ahighly competent partner for solvingmeasurement tasks in process andtrace analysis. N. Schuster

DKD accreditation for Rohde & Schwarz Memmingen

Globalization of markets, stricterproduct liability legislation and stiffer quality demands as the con-sequence mean that manufacturershave to show comparable and thus traceable test results for theirproducts. That calls for reliably calibrated test facilities. They are indispensable if the results, directlyor indirectly, serve human safety, if damage to or loss of products can be averted, and the depend-ability of the results has to be guar-anteed.

For Rohde & Schwarz’s manufac-turing plant in Memmingen this hasmeant, for years already, constantimprovement and refinement of itscalibration practices to high tech-nical standards. The accreditationawarded last year by DKD (Germancalibration service) was a logicalcontinuation of its efforts. The stricthierarchic structure of calibration facilities and the use of examinedand controllable methods ensurethat the individual physical param-eters can be related directly or indi-rectly (through transfer standards) torecognized national or internationalstandards, ie that they are traceable,that the indication produced by aDUT is compared to the standardwith known and defined measure-ment uncertainties (calibration), andthat test procedures are conducted incontrolled and thus reproducibleconditions. Personnel with manyyears of experience and well-founded specialist know-how wereexamined in the course of the accreditation, and they are respon-sible for correct technical handlingof calibration orders, not only fromwithin Rohde & Schwarz but alsofrom other producers.

The Memmingen plant is accreditedwithin DKD for the physical variablesDC voltage, RF power, attenuationand reflection. Based on these pa-rameters it is possible to calibratevoltmeters and RF power meters for example, RF signal generators,receivers, attenuators and calibra-tion sets for network analyzers. Theresults are confirmed by a DKD cali-bration certificate; all non-accredit-ed variables are covered by a workscalibration note.

O. Cziha; L. Stuber

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Newsgrams

Rohde & Schwarz and Tele Denmarkhave signed a cooperation agree-ment for the development of a type-approval test system for TETRA units.Rohde & Schwarz will develop thehardware and software componentsof the system, while Tele Denmarkwill validate the test cases to run onit. The system consists of TETRA Sim-ulator TS8940 (photo) for RF meas-urements based on ETSI standardETS 300 394-1 and a TETRA signal-ling system that conducts protocoltests to ETS 300 394-2 (see Newsfrom Rohde & Schwarz No. 153).

The TETRA simulator is composedprimarily of a system controller,

signalling platform, I/Q modem,two RF signal generators and a spectrum analyzer, and the TETRAsignalling system of a signallingplatform and I/Q modem. The TETRA simulator is due to becomeavailable to test houses and pro-ducers of TETRA units at the end of the year, followed by the TETRAsignalling tester early in 1998. During the interval the implemen-tation of the test cases will be vali-dated to ensure that they run cor-rectly. Currently the possibility of an interim type approval is being examined so that TETRA units can be launched on the market this yearalready. PI

Abis control software for GSM base-station tester CMD54/57

Digital Radiocommunication TesterCMD54/57 (photo) has alwaysbeen able to test every imaginablekind of base station on the air inter-face, but the number of models that could be controlled on the Abis

interface was limited by special-to-producer interface protocols (seeNews from Rohde & Schwarz No. 151). New software options (CMD-K10 through K17) now offerall the necessary requirements forconvenient driving of base stationsfrom Ericsson, Nokia, Italtel, Nortel/Matra, Siemens, Alcatel and Lucenton the Abis interface. All commoninterface protocols are supported:E1 (2.048 Mbits) and T1 (1.56 Mbits)including 16-kbit signalling. The application programs contained ineach option ensure that all necessaryprocesses work simply and surely.They cover complex manual controlfor testing individual base-stationparts, the IEC/IEEE-bus-controlledtest procedure in production and fully automatic testing of an entirebase station by CMD in stand-alonemode. W. Dilling

R&S Bick Mobilfunk renovates DeTeMobil paging system

R&S Bick Mobilfunk, the Rohde &Schwarz subsidiary responsible forprofessional mobile communica-tions, received an order from Deutsche Telekom DeTeMobil to renovate its nationwide paging in-frastructure. The latest generationACCESSNET®-P paging system withmultiprotocol capability will be used,which fuses POCSAG and ERMESservices on a single system platform.It can be expanded at any time and at low cost by further pagingstandards like FLEX and APOC. ACCESSNET®-P was optimizedthroughout for maximum availabilityand low operating costs. New paging services like SCALL havebeen a big market success for DeTeMobil, making expansion of the existing system necessary. Seeing as DeTeMobil is also the winner of an ERMES license, it haschosen in ACCESSNET®-P a systemthat unites all services on one systemplatform and consequently allowshigh utilization of the access and

central office technology. Calls aredistributed inexpensively to the indi-vidual paging transmitters by satel-lite. PI

Expansion of Rohde & Schwarzexecutive

As of 1 January 1997 Michael Von-dermassen, Dipl.-Ing., Dipl.-Oek.(39) joined the Rohde & Schwarz executive, assuming at the same time management of the Sound andTV Broadcasting Division.

Michael Vondermassen was born on21 May 1957 in Hagen in West-phalia. After studying communi-cations – specializing in microwave

engineering – he joined Rohde &Schwarz in 1981 as a specialist incomputer-aided PCB design andfrom 1986 onwards concentrated onsetting up inhouse CAD training.From 1991 to 1993 he took part in apromotion scheme for managerialpersonnel. During this time he washead of CAE and CAD coordinationand user support and also foundtime to study economics in Zurich. In1993 he became personal assistantto the Executive Vice President of the Central Technical Services, Pro-duction and Materials ManagementDivision and in the same year was appointed President of Rohde &Schwarz FTK GmbH in Berlin, anR&S subsidiary that focuses on FMbroadcast transmitters and RF poweramplifiers. In May 1995 Vonder-massen became President of SIT,likewise an R&S subsidiary and alsoin Berlin, which offers consulting andsecurity analysis for industry andpublic authorities and developscrypto products for the protection of information in modern communi-cation systems. PI

Cooperative development of TETRA type-approval test system

The grey transporters of the German Post andTelecommunications Office (BAPT) are probablythe least known government vehicles on thenation’s roads. The new office, created after the postal system reform in 1990, issues andchecks frequencies for radio services, examinesall radio installations and eliminates interferenceto radio and TV reception in private households.The vehicle illustrated in Autobild of 16 No-vember 1996 is fitted with measuring and test equipment worth DM 357,000, a lot of it from Rohde & Schwarz: Loop Antenna HFH2-Z2, Test Receiver ESH, Radiocommuni-

cation Tester CMS plus aportable EMI Receiver

EB100 includingantenna.


Press comments

Analog/digital go-betweenThe international hifi magazine Stereoplaylooked at the subject of digital measurements in its January issue, using Audio Analyzer UPLfrom Rohde & Schwarz for the purpose:

Audio Analyzer UPL from Rohde & Schwarz alsoallows jitter analysis of a kind and precision un-known before. …It is difficult to tell by the con-ventional method exactly what kind of interferenceleads to differences in sound. Noise or sinusoidaljitter can be recognized as such from the histo-gram, but not fineness of structure. This is whereStereoplay’s new Audio Analyzer UPL (from Rohde & Schwarz) comes in. The lab uses it forhighly precise measurements of analog signals andanalyzes digital data not only for their informationcontent but also for clean timing.

New R&S showings mirrored in the pressDuring the Munich electronica 96 show, Rohde &Schwarz staged a press conference to present the new PSP and LV2. Elektronik-Praxis reportedin issue 1/97:

“The mobile Industrial Controller PSP finally makes measurement and control portable”, is how product manager Dietmar Vahldiek summarizesthe advantages of the new Rohde & Schwarz process controllers. They are intended to meet theincreasing demands in systems engineering forsimple and flexible integration of instrumentationplus clear and easy evaluation of results. And the real highlight, emphasizes Vahldiek, is that“because of their compact design and batterypowering, the user can measure automaticallywhenever and wherever.”

Among its production testers Rohde & Schwarz hasupgraded the optical LaserVision board testers:“LV2 now gives you extra test possibilities and ahigher testing rate”, are the major improvementsnamed by product manager Klaus Kundinger.…“Compared to other optical test systems on themarket, LaserVision offers exceptionally high faultdetection at an extremely low pseudo error rate”,emphasizes Kundinger. The test rate of at least 10 components per second matches the speed of modern placement machines. “So”, says Kun-dinger, “that enables direct use for process controlon a production line.”

GSM/DCS Go/Nogo Tester CTD55 first in classThe response was enormous when electroniccommunications magazine Funkschau called onits readers to choose the product of the year for1996. The results were published in the 1/1997issue:

Readers were able to vote for their favourites froma list of suggestions divided into nine categories.GSM/DCS Go/Nogo Tester CTD55 from Rohde &Schwarz had its nose in front in the test category,crossing the line before a Siemens unit (15.4%)and voted product of the year with a big lead(30.7%).

Secure telecommunicationsNumber 4/1997 of Funkschau looked at the subject of industrial espionage, concluding in itsreport that the damage, amounting to millions,could be prevented by the right measures and focusing on the advantages of the ComSave Boxfrom SIT:

Data lines can be secured by the ComSave Boxfrom Gesellschaft für Systeme der Informations-technik (SIT), a subsidiary of Rohde & Schwarz.The unit is connected straight to the modem of acomputer or plugged into the RS-232-C interfaceto encrypt the information flow at a rate of up to115,200 bit/s. It is intended among other thingsfor secure data transmission in telejobs.


Final article

of outlay. Originally it was intended forproject planning of the train radiosystem, but experience of the followingeight years showed the importance ofmeasurements during the constructionphase and after commissioning of aline. The radio measurement carriagethus became an indispensable aid inacceptance testing (quality assurance).In summer 1993 this first radio mea-surement carriage was beginning toshow its age however; damage to thebody due to rusting made a speed lim-it of 100 km/h necessary. Moreover,the modest measurement facilities nolonger fulfilled the grown requirements– every second measurement proved tobe inadequate for some reason or other.

requirements regarding availabilityand quality. This is where measure-ments come in to provide under realis-tic conditions an accurate and reprodu-cible survey of the high-frequency envi-ronment so that gaps in the coveragecan be filled. Realistic can mean only one thing: measurement on all frequencies from the moving train – atits usual speed of course.

Swiss Railways (SBB) had begun backin 1986 to test the quality of radiocoverage in the suburban railwaysystem of Zurich. Test platform was ascrapped carriage that was fitted outfor the installation of the necessary ba-sic measuring instruments at a minimum

Train radiotelephony has for long beenan indispensable part of railway traffic.This important means of communicationdiffers from other radio networks mainlyin that good coverage is required onlyalong the railway track and that there is no need for area coverage like witha mobile-radio network. Train radio-telephony is not only a communicationmedium but also part of a safety network so that it must satisfy special

Swiss rail’s new radio measurement carriage: heading for the future

FIG 1 New radio measurement carriage ofSBB, a passenger coach totally renovated and re-constructed at SBB main workshop Zurich-Olten:with speeds of 160 km/h, three simultaneous fre-quencies and 1st-class measuring convenience

Photo: Roschi Telecommunication AG


Final article

After detailed planning utilizing all theexperience gained over the years, theconstruction of a new radio measurementcarriage on the basis of a modern pas-senger coach of type RIC Bm (FIG 1)began in May 1994. Following totalrenovation of the carriage and con-structional changes, Roschi Telecom-munication AG of Ittigen, the generalagent of Rohde & Schwarz for Switzerland, was awarded a contractfor the supply and installation of themeasuring equipment. Roschi alreadyhad sufficient experience in this field,gained in the maintenance of the mea-suring equipment in the previous radiomeasurement carriage. What is outlinedhere in a few words was in fact a longlist of requirements that had to be met.Some of the requirements: the error ofthe distance measurement for instanceshould be much smaller than 0.1% (which means 130 m with a test route of130 km); definitions of test routes,measurement parameters and analysisshould not mutually affect each other;new results obtained in periodic checksshould be comparable online with

the old ones, etc. Top performance isexpected of the board computer; itshould furnish a large quantity of datawithout delay despite the high measure-

ment rate. By contrast, requirements forredundant power supply or air-condi-tioning – because of the measuring instruments – were relatively modest.

The number of measuring instrumentsis impressive (FIG 2): three Test ReceiversESVD, two Selective Modulation Ana-lyzers FMAS, one Spectrum Analyzer

FIG 2Interior view of mea-surement carriagewith test receivers,modulation analyzersand monitorsPhoto: Roschi Tele-communication AG

FIG 3 Onboard equipment includes radiocoverage measurement instruments as well as Radiocommunication Tester CMT54 (background)

Photo: Rockrohr


Final article

FSA and one Test Receiver ESVP domi-nate the scene. A rooftop antenna isavailable for each frequency band andconnected automatically depending on the respective measurement. The testresults can be output on a colour printer in up to DIN A3 format. Thanksto intelligent firmware, the use of TestReceivers ESVD reduces the amount ofmeasurement enormously: in measur-ing the field-strength profile of the trackeach of the test receivers – triggered bya timebase or distance measuringsystem – can furnish up to 7000 valuesper second. The distance measuringsystem generates a clock pulse every10 cm. Two axles of the SBB radiomeasurement carriage are fitted withsuch a system; moreover, doppler radaris used. The uncertainty of distancemeasurement is less than 0.05% inpractice and the system works fine upto a speed of 230 km/h, although themeasurement carriage has only beenapproved for speeds up to 160 km/h.Since the two modulation analyzersand the three test receivers operateunder computer control during themeasurement, manual intervention onthe part of the operator is not possible.To obtain information however, Test Receiver ESVP and Spectrum AnalyzerFSA allowing manual control are alsopart of the equipment onboard.

For analysis of the received radio signalthe field strength alone is not sufficientso the signal quality must also be eval-uated. This is where Modulation Ana-lyzer FMAS comes in, performing sig-nal analysis of the three received radiochannels as to distortion and frequencydeviation. From the online display of the graphically evaluated analysisthe quality of the radiotelephony announcements can conveniently bechecked. To allow subsequent identifi-cation of any striking features in the fre-quency plot with reference to the testroute, a video camera installed in theengine takes pictures of the environ-ment during the test tour. Picture and de-modulated AF signal are recorded by avideo system and all parameters rele-vant for the test tour are superimposed

on the picture by a video processor.Should mobile video processing be-come necessary, this is not a problemeither: the carriage is equipped withseveral video recorders plus appropri-ate cutting computers.

Even the observer with a technicalbackground is impressed when walkingthrough the new measurement carriage.Everything is immaculately installed,there is nowhere a cable lying aroundthat might disturb this orderliness. Anyequipment that might prove to be usefulsome day finds its place. A cordlesstelephone and/or Natel mobile phone

A3 plot with the exact field-strengthcharacteristic of three frequencies overan accurately defined route section (FIG 4). This new “jewel” of SBB hasbeen in operation since late 1995 formeasurements on their train radiotele-phone networks and not a single resulthas been lost. And the best comes atthe end: the job is completely done atthe end of the test tour, all that remainsis to switch off and get off the train. It’sa pity, we really should have looked outof the window more often.

Christian Rockrohr

Reader service card 154/37 for further informa-tion on train radio measurement systems

can be picked up at the door of eachtest compartment so that communica-tion will not be interrupted on leavingthe carriage (an orange warning vestmust be worn). The compartments areinterconnected with all kinds of RF, dataand AF lines. A spare unit is availablefor each of the key instruments, storedin a custom aluminium case in the largeworkshop compartment. Should one of the numerous train radiotelephonesrequire service or break down, the remedy is there for the taking: Radio-

communication Tester CMT54 fromRohde & Schwarz is on board too (FIG 3). Needless to say, the espressomachine in the neat kitchenette is one of the very best.

Switzerland is a picturesque countryand so during this test tour we wereagain and again tempted to ignore themonitors with their mass of informationand to view the scenery instead, all themore since measurements are auto-matic anyway. While the test tour is furnishing a large amount of results, theonboard computer converts them intoreadable format, eg into a colour DIN

FIG 4 Field-strength profile measured on routeEscholzmatt – Luzern between kilometer 10 and40 at frequencies of 457.875 MHz (red),457.575 MHz (green) and 457.500 MHz (blue)

ROHDE& SCHWARZ GmbH & Co. KG · Mühldorfstraße 15 · D-81671 MünchenP. O. B. 8014 69 · D-81614 München · Tel. (+49 89) 41 29-0 · Fax (+49 89) 41 29-21 64

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