Global Positioning System (GPS)

GNU Radio can be used to create GNSS receivers. The DBSRX daughterboard for the USRP is capable of receiving signal from all contemporary GNSS systems.

Requirements

• For civilian accuracy, the equivalent of $100 GPS receivers, the signal of interest (C/A) is at 1575.42MHz(L1) with a bandwidth of ~2.046MHz.
• For surveying accuracy, the signals of interest (C/A & P(Y)) are at 1575.42MHz(L1) and 1227.6MHz(L2) with a bandwidth of ~20.46MHz at each frequency.
• For military accuracy, you have to add the restricted decrypting hardware on top of the surveying requirements.

The Complete Specification

• U.S. Coast Guard Website (This looks like where civilians should go)
  • http://www.navcen.uscg.gov/gps/geninfo/ICD-GPS-200C%20with%20IRNs%2012345.pdf
  • http://www.navcen.uscg.gov/gps/default.htm
• GPS Support Center Website (Less flashy website for U.S. military GPS users?)
  • http://www.schriever.af.mil/GpsSupportCenter/documents/icd_gps_200c_irn001thru005.pdf
  • http://www.schriever.af.mil/GpsSupportCenter/

Links to papers with details about software GPS implementations

• http://www.datafusion.com/gps/baselinereceiver.pdf
• http://gps.ece.cornell.edu/swreceiver_paper5_ION.pdf
• http://csc.postech.ac.kr/publication/archive/comm-choi2002.pdf
• http://www.navsys.com/Papers/

Overview of GPS Operation

• http://www.collaborium.org/onsite/jos2000/related/GPS/DECODING.HTM
• http://gpsinformation.net/main/gpslock.htm

General GPS Information

• http://gpsinformation.net/
• A decent introduction to GPS, and even better, SDR implementations thereof, is "Fundamentals of Global Positioning System Receivers: A software approach", by James Bao-Yen Tsui (ISBN 0-471-38154-3).

SBAS/WAAS/EGNOS/MSAS information here

• http://www.faa.gov/ASD/international/GUIDANCE_MATL/2892b_c1.pdf - FAA WAAS Specification (non-canonical link, a C version exists somewhere)
• http://gps.losangeles.af.mil/prn/sbas_ranging_codes.htm - currently registered C/A PN codes for SBAS satellites
• http://www.rtca.org/downloads/doclist_1004.htm#_Toc86220673 - RTCA/DO-229 (What is this?)
• <put your tidbits here>

OpenGNSS Community Information

• Mailing List: http://lists.psas.pdx.edu/mailman/listinfo/opengnss
• Wiki: http://psas.pdx.edu/GPS/OpenGnssProjects

Projects

• http://code.google.com/p/opengnss Trond Danielsen, GPLv2 python-based GPS receiver, last change 2007
• https://projects.cecs.pdx.edu/~icarroll/SoftwareGPSCorrelator/index.cgi/wiki FIXME: broken link
• http://github.com/gps-sdr/gps-sdr Gregory W. Heckler, USRP-based, but not GNU Radio, used to be http://www.gps-sdr.com/
• There is an OSS implementation of the decoding part in OpenSourceGPS at http://home.earthlink.net/~cwkelley/
• There is a project at the proof-of-concept stage at http://www.kamieniecki.com/krys/gps/ which currently processes simulated signals with software correlators.
• One of the most interesting projects ever dealing with GPS and GLONASS in a single package was done by Matjaz Vidmar, S53MV. It is available here http://lea.hamradio.si/~s53mv/navsats/theory.html (software, hardware designs, etc.)

The Russian GLONASS

• http://www.glonass-ianc.rsa.ru/pls/htmldb/f?p=202:1:12061333542270124939 The Russians added needless complications when they selected a silly time-scale for their system and decided to share the spreading codes between satellites. GLONASS also consumes a lot more bandwidth. However, this would be an excellent demonstration of an SDR's adaptability, since a working software GPS receiver has all the necessary components that a GLONASS receiver requires. One just rearranges them differently. GALILEO falls into the same category.

Q&A

Q: What about DGPS for GPS positioning accuracy improvement?

A: For the continental US, WAAS is more reasonable. The marine DGPS beacons that operate at LF (~300kHz) would require another RF path and related antenna.

Q: What about WAAS, EGNOS (Europe), MSAS (Japan / Asia) for GPS positioning accuracy improvement?

A: WAAS is broadcast on the same L1 frequency as GPS itself. So WAAS support is a pure software feature.

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CategoryRadio

注： GNU Radio GPS（原文出处，翻译整理仅供参考!）