Improved Encryption-Mode GPS Receiver

An improved Global Positioning System (GPS) receiver, which processes an encrypted P-code signal without knowledge of the encryption code (denoted here as A-codeless mode), includes an auxiliary antenna and associated additional signal-processing circuitry. The improved design of this receiver makes it possible to achieve signal-to-noise ratios (SNRs) greater than that of prior A-codeless-mode GPS receivers, especially when GPS satellites appear at low elevation angles.