Patent ID: 8068054

Claim:
An arrangement in an environment that includes a plurality of satellites, each transmitting a ranging digital data signal of a given bandwidth that is modulated with a carrier, comprising: a receiver-front-end module that concurrently receives the ranging signals, where each of the received signals comprises a sum of two component signals, where a first of the component signals is a data signal that is modulated by a known code, and a second of the component signals is said data signal that is modulated by a secret code, and the two component signals are modulated by respective carrier signals, where each of the received signals experiences a transit delay and Doppler frequency shift during transit to said receiver-front-end module, and where the transit delays and Doppler frequency shifts of the received signals are related to positions and movements of said satellites relative to said front-end module, said front-end module forming a front-end signal that corresponds to comingled sum of the concurrently received signals; a first processing module for converting said front-end signal to a processed signal having a bandwidth that is not markedly reduced from said given bandwidth, and forwarding said processed signal to a second processing module for correlating said processed signal with a supplicant signal having a bandwidth that is essentially the same as the bandwidth of said processed signal, said supplicant signal arriving from a supplicant receiver that receives the ranging signals, and said second processing module offering results of said correlating for authentication, said arrangement being devoid of means for generating said secret code; and an associated physical attribute of said arrangement for favoring reception by said receiver-front-end module of the signals transmitted by said satellites rather than signals transmitted by other than said satellites.