Discriminator system for timing error detection in presence and absence of multipath conditions

摘要

In a code tracking loop, a multipath discriminator is configured to generate a first tracking error corresponding to a received signal in the presence of multipath interference and/or at low signal level. A line-of-sight (LOS) discriminator is configured to generate a second tracking error corresponding to the received signal. A multipath switch is configured to i) detect the presence of multipath interference in the received signal and/or a low signal level of the received signal compared to a threshold, and ii) indicate whether the first tracking error or the second tracking error is to be utilized.

主权项

1. An apparatus, comprising:
a multipath discriminator configured to generate a first tracking error that estimates a phase difference between a received signal and a local reference signal, and that corresponds to the received signal (i) in the presence of multipath interference and/or (ii) at low signal level; a line-of-sight (LOS) discriminator configured to generate a second tracking error that estimates the phase difference between the received signal and the local reference signal; a multipath switch configured to:
detect (i) a presence of multipath interference in the received signal and/or (ii) a low signal level of the received signal as compared to a threshold, andindicate whether either (i) the first tracking error is to be utilized or (ii) the second tracking error is to be utilized; a code tracking loop configured to utilize the first tracking error or the second tracking error, as indicated by the multipath switch, to adjust the synchronization between the local reference signal and the received signal in an attempt to reduce code phase error; and a plurality of correlators configured to correlate the received signal with a plurality of delayed versions of the local reference signal, the plurality of correlators generating at least an early correlation signal and a prompt correlation signal.