ASSESSMENT OF THE EGNOS SIGNAL AVAILABILITY FOR LAND MOBILE USER

Assessment of the EGNOS Signal Availability for Land Mobile User FEL ČVUT

ASSESSMENT OF THE EGNOS SIGNAL AVAILABILITY FOR

LAND MOBILE USER Pavel Kovář

František Vejražka

Libor Seidl

Pavel Puričer

Czech Technical University in Prague


• EGNOS – main characteristics

• Mobile satellite channel modelling

• EGNOS fast detection algorithm

• Experimental GNSS receiver

• Measurements and results

• Conclusions

Agenda







• Conclusions

Agenda


EGNOS – main characteristics

• EGNOSEuropean Geostationary Navigation Overlay System– SBAS system which disseminates for GPS and

GLONASS in Europe region • Wide Area Differential Corrections• integrity information

– provides users with Safety of Live Services– is compatible with

• US – WAAS• Asia MSAS and • Indian GAGAN



• EGNOS Satellites – full constellation

Satellite PositionElevation in Prague

Elevation in

St. PetersburgPRN

Inmarsat III (AOR-E) 15.5°W 26° 12° 120

ESA Artemis 21.5°E 32° 21.5° 124

Inmarsat III F5 25°E 32° 22° 126

Inmarsat IOR 64.5°E 15° 16° 131



• EGNOS – ESTB constellation winter 2005

Satellite PositionElevation in Prague

Elevation in

St. PetersburgPRN

Inmarsat III (AOR-E) 15.5°W 26° 12° 120

ESA Artemis 21.5°E 32° 21.5° 124

Inmarsat III F5 25°E 32° 22° 126

Inmarsat IOR 64.5°E 15° 16° 131



• Land mobile user problem:– Limited visibility of the EGNOS satellites



• Land mobile user problem:– Limited visibility of the EGNOS satellites

EGNOSGNSS







• Conclusions

Agenda


Mobile satellite channel modelling

• Two state Markov process – dependent on run distance – states

• blocked Line Of Sight (LOS) • unblocked LOS

– model parameters• μ – partial intensity of blocked LOS • λ – partial intensity of unblocked LOS• determined by mobile experiment



-=

-

A-

=-

A

-=

-

A

-=

-

A

-=

-

A

00 01

10 11

T T

T T

e ep T p T

Tp T p T

e e

P

Particular transition intensity matrix

Particular transition probability matrix



Analytically derived statistics• Probability of the EGNOS signal reception

• Probability of reception of at last one message from N possible ones

• Statistics of the antenna diversity reception (not discussed here)







• Conclusions

Agenda


IFrs rs

2R

Transformation to thebaseband

rs rs2

Routput

Parallelcorrelator

Noncoherentintegration

Signaldetection

EGNOS fast detection algorithm

• Parallel correlation method


EGNOS fast detection algorithm

Features

• parallel correlation

• fast response on the EGNOS signal (8 ms)

• shadowing process measurement in real time







• Conclusions

Agenda


PowerPCjádro

Experimental GNSS Receiver

PowerPCjádro

LNA

Channel 1

A/D

FPGA XilinxVirtex-II Pro

DSP and ProcessorRF unitGNSS antenna

Synthesizer

LNA

LNA

Channel 2

Channel 3



Main features:• Four independent RF channels

– Intermediate frequency 140 MHz

• Sampling frequency up to 80 MHz• Digital signal processing - Xilings Virtex II Pro

– Two PowerPC processors (RISC 32 bits, 400 MHz)– 5M gates programmable logic– 232 embedded multipliers

• 19” rack housing


• ADC Board– 4 channels– 8 bits– Sampling frequency 80 MHz

• FPGA Virtex-II Pro


Digital signal processor







• Conclusions

Agenda


Measurements and results

Antenna Odometer on trailer

Experimentalreceiver

Car installation



Model parameters – PRN 131

Environmentμ

[m-1]

λ

[m-1]Visibility

Town – modern house building

0.06 - 0.1 0.02 - 0.04 60 - 80 %

Town – narrow streets

0.02 0.02 50 %

Country 0.002 - 0.006 0.01 - 0.02 90 - 95 %



Typical measurement results

0 1000 2000 3000 4000 5000 6000 7000

Unblock

Block

Distance [m]

0 500 1000 1500 2000 2500 3000 3500 4000

Unblock

Block

Distance [m]

Country

Town



Comparison of the measured satellite blocked and unblocked distance distribution with the model

0 100 200 300 400 5000

0.005

0.01

0.015

0.02

0.025Unblocked distance distribution

Distance [m]

Pdf

Theoretical valueEstimation from realization

0 100 200 300 400 5000

0.005

0.01

0.015

0.02

0.025Blocked distance distribution

Distance [m]

Pdf

Theoretical valueEstimation from realization



Environment

Probability of the EGNOS message reception

N=1 N=2 N=3

Velocity [m/s]

1 5 10 20 1 5 10 20 1 5 10 20

Town – modern house building

0,66 0,64 0,61 0,57 0,66 0,66 0,64 0,61 0,67 0,68 0,69 0,68

Town – narrow streets

0,52 0,48 0,43 0,38 0,53 0,53 0,48 0,44 0,54 0,57 0,55 0,53

Country 0,93 0,92 0,90 0,88 0,94 0,93 0,92 0,93 0,94 0,95 0,94 0,95


Proč má tabulka jiný tvar (podbarvení ap.) než předchozí??????A co je N????



Comparison of the measured satellite blocked and unblocked distance distribution with the model

510

1520

2530

2

4

6

8

100.4

0.5

0.6

0.7

0.8

0.9

1

v [m/s]N

Pr

510

1520

2530

2

4

6

8

100.4

0.5

0.6

0.7

0.8

0.9

1

v [m/s]N

Pr


Co je blocking a co ne, popis obrázků i os zcela chybí!!!!!!!!







• Conclusions

Agenda


Conclusions

• Markov model of shadowing dependent on distance was approved

• The model parameters for different environment were determined in ESTB phase

• Good conformity between model and measurement was obtained


Thank you for your attention

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ASSESSMENT OF THE EGNOS SIGNAL AVAILABILITY FOR LAND MOBILE USER