Patent ID: 8457876

Claim:
A communications system for determining the position of an object, said system comprising: an interrogator remote from the object and including circuits that: receive GPS signals from GPS satellites; for one of the GPS satellites associated with the GPS signals, transmit pre-positioning data for the GPS satellite, including a pseudorandom noise (PRN) code number, a Doppler frequency offset and a code phase offset and a tracking signal including reference time and frequency information; and determine a pseudorange associated with a received correlation snapshot, wherein the correlation snapshot comprises correlator sums and a range offset in chips; and a transponder positioned on the object and including circuits that receive: receive the pre-positioning data and the tracking signal; collect RF samples of the GPS signals; correlate the RF samples of the GPS signals against replicas of a GPS signal based on the PRN code number, the Doppler frequency offset, and the code phase offset in the prepositioning data and the reference time and frequency information in the tracking signal to produce the correlation snapshot; and transmit the correlation snapshot to the interrogator.