A Survey on SQM for Sat-Nav Systems

Reduction of multipath effects on the satellite signals can be accomplished with innovative hardware design. Although such methods are effective in reducing multipath and the effects due to it, they are not practical enough, especially in varying environmental conditions. Implementation of Narrow Correlator spacing technique can reduce multipath effects to a great extent but has no advantage over carrier phase measurement accuracy. Pulse Aperture Correlator (PAC) although takes full advantage over Narrow correlator technique, it has low Signal to Noise ratio (SNR) and cannot remove close-in multipath. This paper provides an overview of early performance results obtained by using different correlator techniques for monitoring the quality of satellite signals. This paper proposes implementation of Vision Correlator for Signal Quality Monitoring of satellite signals. Vision Correlator is particularly useful in removing close-in multipath and also mitigates the effects of multipath on the signals in the line of sight. An experimental setup to check for the performance of Vision Correlator against the standard correlator has been proposed. Further, IRNSS architecture and frame format have been discussed.