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/
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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 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
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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
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
13
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
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