CGSIG MEETING

PRAGUE.1999

POSSIBILTIES & LIMITATIONS

PRECISION AND ACCURACY

• PRECISION OF GPS•ACCURACY OF GPS

ρ = c .τΔρ = c . Δτ

Δρ = 3.108 m/s . 10 -12 s

Δρ = 0.3 mm

PRECISION OF THE GPS SYSTEM

6om

Tipical satellite path without S/A

0 11:54

U

U= User equivalent range error

SPS USER EQUIVALENT ERROR [m]

ACCURACY OF THE GPS SYSTEM

SA AS C/A RT MAX

YESNOYESNO

YESYESNONO

100(150)40(60)

100(150)40(60)

300(450)120(180)300(450)

40(60)

1oom

Tipical satellite path with S/A

0 11:54

U= User equivalent range error

U

1min 10min 1hour 12hours 1day

100

300

Pos. error

Obs. time

1m

3m

Postioning accuracy vs Observation time

3min

0

PRC

RRC

RTCMRTCMSC 104SC 104Ver 2.0Ver 2.0

COSTCOST

ACCURACY ACCURACY 1σ1σ

100m 10m 1m 10cm 1cm 1mm 0.3mm

POSITONING COST vs ACCURACYPOSITONING COST vs ACCURACY

DemandDemand

ACCURACY ACCURACY 1σ1σ

100m 10m 1m 10cm 1cm 1mm 0.3mm

POSITONING COST vs ACCURACYPOSITONING COST vs ACCURACY

DGPSDGPS RTKRTK POSTPROCESSINGPOSTPROCESSING

S T A N D A R D P O S I T I O N I N G S E R V I C EG L O B A L R A N G E ( 1 0 - 1 0 0 ) k m

O b s e r v a t i o nt e c h n i q u e

A b s o l u t er e a l t i m e

A b s o l u t e1 h o u r

A b s o l u t e1 d a y

R e l a t i v er e a l t i m e

R e l a t i v e> 1 m i n

R e l a t i v e> 1 h o u r P P

R e l a t i v e 1 d a y

C a r r ie r p h a s e H 1 0 0 m 9 5 %V 1 5 0 m 9 5 %

3 0 1 5 m4 5 1 5 m

1 m 1 . 5 m

< 0 . 3 m < 0 . 1 m < 0 . 0 3 m < 0 . 0 0 0 3 mL 1 + L 2

C a r r ie r s m o o t h e dC / A c o d e

H 1 0 0 m 9 5 %V 1 5 0 m 9 5 %

3 0 1 5 m4 5 1 5 m

1 m 1 . 5 m

< 1 m < 0 . 5 m < 0 . 3 m < 0 . 3 m

C / A c o d e H 1 0 0 m 9 5 %V 1 5 0 m 9 5 %

3 0 1 5 m4 5 1 5 m

3 m 5 m

< 5 m < 3 m < 3 m < 3 m

R e a lt im e = 1 - 1 0 H z

DGPS Corrections I.C/A code

PRCi = ρ’i -| r - R |i RRCi = PRCi - PRCi-1

ρi = | r - R |i + PRCi

ρi = ρi-1 + RRCi-1

RTCM v2.0

True range

PRC : Pseudorange correctionRRC: Range rate correction

r : satellite positionR : reference position

ρ’ : pseudorangeρ : corrected range

BASE

REC

DGPS Corrections II.Carrier phase

CFCi = Φ’i - FRAC( ρi /(N*λ))N = INT (ρi / λ)

DFCi = CFCi - CFCi-1

Φi = Φ’i + CFCi

Φi = Φi -1 + RFCi -1

RTCM v2.1

True phase

CFC : Carrier Phase CorrectionRPC: Rate of Phase Correction

N : resolved ambiguityΦ’ : raw phase

ρ : corrected rangeΦ : correct phase

BASE

REC

TYPE TRANSMITTER RADIO BAND LAT.(s)

UPDT(s)

NAV ERROR()

POS ERROR(100 km)

OBS TIME(min)

TRANSMISSION RATE

RANGE SERVICE

Geostationary L-Band 65 5s 10m10m/s

1-3m 3-10min 50-300bps GlobalR = 5Mm

INMARSAT(US)LANDSTAR(UK)MTSAS (J)CHINA 2002INDIA ?

GNSS(= GPS +GLONASS )

GPSL-Band

R = 5Mm EU-GNSSGALILEO

GEOSYNC.

WAAS

GPS-SecondCivilRadio-Beacon 300KHz 10ms 5s 5m

1m/s1-5m 2-5min 300bps 500-100km USCG

Dassault- SercelLong wave 80KHz 10ms 5s 5m

1m/s3-10m 2-5min 50bps R = 1000km ULW

FM-Radio RDS UHF88-108 MHz

1ms 1-2s 3m0.1m/s

<1m 30-120s 1187.5bps Countrywide GPS-NetzDCISAPOSbys@t

FM-RadioDARC

UHF88-108 MHz

1s 5s 1m <10cm 5s 19.6Kbps Countrywide SAPOS 2002GPS NETZ

Ground wave Global GWEN

MAAS

GSM,Iridium TEL 0.01m/s 9.6Kbps GlobalRadio-modem 400MHz 1s 1s - <10cm 2min 19.6Kbps 1-30km RTK

KARTLAAS

Pseudolite L1, L2 1s 1s 0.1-1m0.1m/s

<10cm 1s 50bps 1-5km

WADGPS FM-NetworkRDS ,DARC

UHF 10ms 1-2s 3m0.1m/s

<1m 30-120s 1187.5bps Continental

DIFFERENTIAL CORRECTIONSDIFFERENTIAL CORRECTIONS forfor

REALTIME PRECISE NAVIGATIONREALTIME PRECISE NAVIGATION

Geostationary satellite Terrestrial radioGeostationary satellite Terrestrial radio

•Wide area coverage Contry to continentalWide area coverage Contry to continental•Availabilty in high seas Availabilty in high seas Availabilty in urbanareas Availabilty in urbanareas•Accuracy 5 - 10 m Accuracy submeterAccuracy 5 - 10 m Accuracy submeter•Latency Latency 6 sec Latency 6 sec Latency 0.1 sec 0.1 sec•Low elevation Topographic warmholesLow elevation Topographic warmholes•Expensive antenna Inexpensive antennaExpensive antenna Inexpensive antenna•Sophisticated receiver Simple pager receiverSophisticated receiver Simple pager receiver

75

50

0 19 57 76

Deviation (%)

Frequency (KHz)

FM BROADCASTING SITES