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3
. Yunck, T. P., W. I. Bertiger, S. C. Wu, Y. E. Bar-Sever,
E. J. Christensen, B. J. Haines, S. M. Lichten, R. J.
Muellerschoen, Y. Vigue, and P. Willis, First Assess-
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. Bertiger, W. I., Y. E. Bar-Sever, E. J. Christensen,
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4
Fig. 12 ᎐ SNOE Clock Solution for Two Consecutive Data
Segments
To accomplish this advance, a patent-pending
algorithm was developed that can process Doppler
plus ambiguous pseudorange observables collected
with widely spaced epochs Ži.e., sparse sampling..
In addition, a new low-power, high-stability, multi-
frequency radio-frequency downconverter was de-
signed and space-qualified. These key advances led
to a system that exceeded orbit accuracy goals by
almost a factor of 3.
5. Wu, S. C., W. Bertiger, J. Srinivasan, and A. Reichert,
MicroGPS for Orbit Determination of Earth Satel-
lites, presented at The Institute of Navigation’s Na-
tional Technical Meeting, Santa Monica, CA, Jan-
uary 1996.
6
. Wu, S. C., D. Kuang, S. M. Lichten, S. Nandi, L. J.
Romans, and J. M. Srinivasan, Demonstration of
MicroGPS for Low-Cost Orbit Determination,
AASrAIAA Astrodynamics Specialist Conference,
Sun Valley, ID, August 1998.
ACKNOWLEDGMENT
The work described in this paper was carried out
by the Jet Propulsion Laboratory, California Insti-
tute of Technology, under contract with NASA.
Funding was provided by NASA and the Depart-
ment of Defense’s BMDO Office.
7
. Bertiger, W. I., Y. E. Bar-Sever, B. J. Haines, B. A.
Iijima, S. M. Lichten, U. J. Lindqwister, A. J. Man-
nucci, R. J. Muellerschoen, T. N. Munson, A. W.
Moore, L. J. Romans, B. D. Wilson, S. C. Wu, T. P.
Yunck, G. Piesinger, and M. Whitehead, A Prototype
Real-Time Wide Area Differential GPS System, pre-
sented at The Institute of Navigation’s National
Technical Meeting, Santa Monica, CA, January 1997.
. Webb, F. B. and J. F. Zumberge Žeds.., An Introduc-
The microGPS project was carried out by JPL in
partnership with the Colorado Center for Atmo-
spheric Research, and the authors acknowledge the
valuable contributions of Dr. Penina Axelrad and
Angie Reichert. The authors would also like to ac-
knowledge the much-appreciated efforts of Dr.
Charles Barth and his SNOE science and engineer-
ing team at the University of Colorado’s Laboratory
of Atmospheric and Space Physics, who integrated
and currently operate the microGPS payload. The
authors further would like to recognize the early
conceptualizations of Tomas Svitek of Stellar Inno-
vations Inc. and Tom Meehan of NASArJPL that
eventually led to the development of microGPS.
8
tion to GIPSYr OASIS II, JPL Internal Document
D-11088, July 1993.
. Bierman, G. J., Factorization Methods for Discrete
Sequential Estimation, Academic Press, New York,
NY, 1977.
9
1
0. Cathey, W. T., Optical Information Processing and
Holography, Wily-Interscience, New York, NY, 1974.
1. Meehan, T. K. et al., ‘‘GPS-On-A-Chip’’ ᎏAn Ad-
vanced GPS Receiver for Spacecraft, presented at The
Institute of Navigation GPS-98, Nashville, TN,
September 1998.
1
Based on a paper presented at The Institute of Naviga-
tion ION GPS-98, Nashville, Tennessee, September 1998.
12. Solomon, S. et al., The SNOE Spacecraft, Integration,
Test, Launch, Operation and On-orbit Performance,
Proceedings of the 12th AIAArUSU Conference on
Small Satellites, SSC98-IV-3, 1998.
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