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.
- For civilian accuracy, the equivalent of $100 GPS receivers, the
signal of interest (C/A) is at 1575.42MHz(L1) with a bandwidth of
- 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
- 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
- GPS Support Center Website (Less flashy website for U.S. military
to papers with details about software GPS implementations
Overview of GPS Operation
General GPS Information
- 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).
OpenGNSS Community Information
The Russian GLONASS
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: What about DGPS for GPS positioning accuracy
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.