Patent ID: 8837728

Claim:
A method for location authentication, the method comprising: receiving at a server a client received coded satellite signal from a client device; receiving at the server a server received coded satellite signal from a satellite receiver device; estimating at the server an estimated client known high-rate code based on one of: the client received coded satellite signal and the server received coded satellite signal; extracting at the server an estimated client unknown low-rate code signal from the client received coded satellite signal based on the estimated client known high-rate code; estimating at the server an estimated server known high-rate code based on the server received coded satellite signal; extracting at the server an estimated server unknown low-rate code signal from the client received coded satellite signal based on the estimated server known high-rate code; and comparing at the server the estimated client unknown low-rate code signal to the estimated server unknown low-rate code signal to provide an unknown low-rate code comparison result by multiplying the estimated server unknown low-rate code signal by the estimated client unknown low-rate code signal delayed by a client delay.