Abstract
The cross correlation properties of the 1023 chip Gold (C/A) codes can
cause difficulties in scenarios where both strong and weak GPS signals need
to be processed. Such cases are increasingly likely given the new
applications of GPS, with examples being the processing of GPS signals in
E911 cellular phone applications and the use of bistatic GPS as a remote
sensing tool. This coupled with the increasing use of software-defined radio
(software correlation) for either cost-saving or flexibility enhancing reasons
have resulted in a need to mitigate cross correlations within such systems.
This paper provides details on two techniques developed by the authors for
the mitigation of GPS cross correlations, both of which have been tested and
implemented within a software correlator that has been written in the C
programming language. Details on the software correlator are also provided
as the table lookup requirements for the correlator are smaller than those
previously reported. Test results indicating the effectiveness of the
algorithms are presented, with a comparison between the two methods being
performed., The datasets containing cross correlations were obtained by
capturing the output of a GPS radio front end chip attached to a hardware
GPS simulator.