1

Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering

Workshop, October 27 – 28, 2006, Quebec city, QuebecSükeová, Liliána

L2C Data Collection and Analysis using a Trimble R7 GPS Receiver

Liliana Sükeova

Department of Geodesy and Geomatics EngineeringUniversity of New Brunswick

Fredericton, NB

2

Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering

Workshop, October 27 – 28, 2006, Quebec city, QuebecSükeová, Liliána

Conclusion

Outline

Background and objectives

Project description

Observations and their analysis

3

Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering

Workshop, October 27 – 28, 2006, Quebec city, QuebecSükeová, Liliána

Background GPS Modernization

a new open civil signal available on L2 frequency – L2C – currently broadcast by Block IIR-M satellites:

• PRN 17 since 15.12.2005 • PRN 31 since 12.10.2006

L2C signal tracking network L2C capable GPS receivers deployed to existing and new

stations

Trimble R7 receiver on loan to UNB Establishing UNB3 as a part of the L2C tracking network

4

Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering

Workshop, October 27 – 28, 2006, Quebec city, QuebecSükeová, Liliána

Objectives

General objective to analyze the modernized L2C signal

Specific objectives to establish a station using Trimble R7 receiver to collect the data containing the new L2C

observables to test the receiver’s firmware version

5

Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering

Workshop, October 27 – 28, 2006, Quebec city, QuebecSükeová, Liliána

Project description

L2C signal tracking network

Trimble R7 at UNB becomes a part of L2C tracking network successfully tracks the modernized L2C signal

6

Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering

Workshop, October 27 – 28, 2006, Quebec city, QuebecSükeová, Liliána

Project description Establishing UNB3

Trimble R7 connected to the same antenna used by IGS

station UNB1 (currently UNBJ), by means of an antenna splitter

(UNB, Fredericton, NB)

L2C data collection since January 11th, 2006

until October 10th, 2006

30 second daily files containing the new L2C uploaded to the

site at the Crustal Dynamic Data Information System (CDDIS)

ftp://cddis.gsfc.nasa.gov/gps/data/l2ctest/daily/2006/

7

Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering

Workshop, October 27 – 28, 2006, Quebec city, QuebecSükeová, Liliána

Observations and their analyses

Data processing to create daily observation and navigation files program

TEQC was used, v. 5.11.2005, provided by UNAVCO

to accommodate the new GPS L2C pseudorange

observable a new code (C2) was defined in RINEX

(v. 2.11) observation files.

The full command line reads:teqc +C2 -tr d +nav *.06n *.dat > *.06o

8

Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering

Workshop, October 27 – 28, 2006, Quebec city, QuebecSükeová, Liliána

Observations and their analysis

Signal-to-noise ratio on L1: Signal-to-noise ratio on L2:

9

Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering

Workshop, October 27 – 28, 2006, Quebec city, QuebecSükeová, Liliána

Observations and their analysis

C/A and L2C SNR – PRN 17C/A and P2 SNR – PRN 11

10 deg 70 deg 10 deg 10 deg 80 deg 10 deg

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Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering

Workshop, October 27 – 28, 2006, Quebec city, QuebecSükeová, Liliána

Observations and their analysis

Compute code multipath and noise level of C/A and L2C code pseudorange for PRN 17 of P2 and C/A code for PRN 11

code multipath and noise level =

).(2

)(

22

11

11

2222

21

22

1122

21

22

21

2122

21

22

12122

21

22

1

noisempNff

f

noisempNff

ff

noisempff

f

ff

fp pp

11

Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering

Workshop, October 27 – 28, 2006, Quebec city, QuebecSükeová, Liliána

Observations and their analysis

,

stdL2C = 0.611 m stdC/A = 0.270 m

L2C and C/A code multipath and noise level – PRN 17, 16.01.2006 with the mean removed (offset by the carrier phase ambiguities)

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Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering

Workshop, October 27 – 28, 2006, Quebec city, QuebecSükeová, Liliána

Observations and their analysis P2 and C/A code multipath and noise level – PRN 11, 16.01.2006

with the mean removed (offset by the carrier phase ambiguities)

stdP2 = 0.438 m stdC/A = 0.314 m

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Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering

Workshop, October 27 – 28, 2006, Quebec city, QuebecSükeová, Liliána

Observations and their analysis

Analyses of code multipath and noise level

According to (Simsky et al., 2006) the same level of noise and multipath is expected on C/A and L2C

contrast with this assumption found in Trimble R7 => the firmware of Trimble R7 (v. 2.26, v. 2.28) does

not combine CM and CL code wavelengths of the L2C signal

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Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering

Workshop, October 27 – 28, 2006, Quebec city, QuebecSükeová, Liliána

Observations and their analysis

Other incongruities in the firmware of Trimble R7

after processing data with GAPS -

found an inconsistency between carrier-phase and

pseudorange measurements => a cycle-slip-like effect

observations from consecutive days can not be used

sequentially without re-initializing ambiguities for all

satellites at each day crossover

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Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering

Workshop, October 27 – 28, 2006, Quebec city, QuebecSükeová, Liliána

Conclusions

More advanced signal structure of L2C code over the C/A code, SRN of L2C is higher than P2 code, values similar to SNR of C/A code

Multipath and noise level of L2C is higher than that of C/A code - contrast with the assumption

inconsistency between carrier-phase and pseudorange measurements

Current work: Analysis of data collected with different antennas, receivers

(from all tracking stations)

Future work: Analysis of simulated data sets of L2C signal with Spirent simulator

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Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering

Workshop, October 27 – 28, 2006, Quebec city, QuebecSükeová, Liliána

Acknowledgements

GEOIDE Network for funding

Cansel for loan of Trimble R7 receiver

THANK YOU