In a software-defined GPS receiver (SGR), the carriersynchronization typically adopts arctangent or itsapproximations as the phase discriminator because itmaximizes SNR for analog signal cases. However, forfew-bits ADC which are always used to implement a realtimeSGR, this method greatly reduces the accuracy ofphase estimate because of the significant quantizationerror, e.g., greater than 2 dB in power degradation for 1-bit ADC [1][2].In this paper, a novel phase discriminator based on puredigital approach is implemented in 1-bit ADC SGR. It canbe shown that the novel phase discriminator achieves oneorderhigher accuracy on phase estimate than traditionalarctangent method under high SNR environment. Inaddition, the proposed phase discriminator is combinedwith a post correlator phase compensation (PCPC)structure to address the navigation bit transition issuethroughout tracking stage. The real GPS data is tested onour self-developed SGR to verify the feasibility of thecombined structure. The less computational load than thatof APD and higher accuracy than other typical phasediscriminators approximating APD, demonstrate thesuperiority of the proposed phase discriminator in SGRimplementation.
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