ÜDVÖZLI ÖNÖKET

A Budapesti Műszaki és Gazdaságtudományi EgyetemÁltalános és Felsőgeodézia Tanszéke

BUDAPEST

TÉRINFORMATIKAI GPS ALKALMAZÁSOK

Dr Graczka Gyulagraczka@altgeod.agt.bme.hu

yY

X Y

Z r

R

e.ρ

R= r - e.ρ

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)24(36)

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

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

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

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

75

50

0 19 57 76

Deviation (%)

Frequency (KHz)

1999 CEI Workshop,Trieste Prof. Dr. GRACZKA Gyula

FM BROADCASTING SITES

NAVSAT

VEHICLE

CONSIGNMENT

SENSOR

TELECOM

MAP

DISPATCHERACC. PANIC

NET

INTELLIGENT TRANSPORT SECURITY SYSTEM