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L2C Data Collection and Analysis using a Trimble R7 GPS Receiver

L2C Data Collection and Analysis using a Trimble R7 GPS Receiver. Liliana S ü keova Department of Geodesy and Geomatics Engineering University of New Brunswick Fredericton, NB. Outline. Background and objectives. Project description. Observations and their analysis. Conclusion.

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L2C Data Collection and Analysis using a Trimble R7 GPS Receiver

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  1. L2C Data Collection and Analysis using a Trimble R7 GPS Receiver Liliana Sükeova Department of Geodesy and Geomatics Engineering University of New Brunswick Fredericton, NB

  2. Outline • Background and objectives • Project description • Observations and their analysis • Conclusion

  3. 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. 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 Objectives

  5. Project description • L2C signal tracking network • Trimble R7 at UNB • becomes a part of L2C tracking network • successfully tracks the modernized L2C signal

  6. 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/ Project description

  7. 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. Observations and their analysis Signal-to-noise ratio on L1: Signal-to-noise ratio on L2:

  9. Observations and their analysis C/A and P2 SNR – PRN 11 C/A and L2C SNR – PRN 17 70 deg 10 deg 10 deg 80 deg 10 deg 10 deg

  10. 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 =

  11. Observations and their analysis • L2C and C/A code multipath and noise level – PRN 17, 16.01.2006 • with the mean removed (offset by the carrier phase ambiguities) , stdL2C = 0.611 m stdC/A = 0.270 m

  12. 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

  13. 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

  14. 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

  15. 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

  16. Acknowledgements • GEOIDE Network for funding • Cansel for loan of Trimble R7 receiver THANK YOU

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