Implementation of an Innovative Phase Discriminator for Improved Tracking Performance in One-Bit Software GPS Receiver

Chieh-Fu Chang, Ru-Muh Yang, Ming-Seng Kao

Abstract:	In a software-defined GPS receiver (SGR), the carrier synchronization typically adopts arctangent or its approximations as the phase discriminator because it maximizes SNR for analog signal cases. However, for few-bits ADC which are always used to implement a realtime SGR, this method greatly reduces the accuracy of phase estimate because of the significant quantization error, e.g., greater than 2 dB in power degradation for 1- bit ADC [1][2]. In this paper, a novel phase discriminator based on pure digital approach is implemented in 1-bit ADC SGR. It can be shown that the novel phase discriminator achieves oneorder higher accuracy on phase estimate than traditional arctangent method under high SNR environment. In addition, the proposed phase discriminator is combined with a post correlator phase compensation (PCPC) structure to address the navigation bit transition issue throughout tracking stage. The real GPS data is tested on our self-developed SGR to verify the feasibility of the combined structure. The less computational load than that of APD and higher accuracy than other typical phase discriminators approximating APD, demonstrate the superiority of the proposed phase discriminator in SGR implementation.
Published in:	Proceedings of the 2008 National Technical Meeting of The Institute of Navigation January 28 - 30, 2008 The Catamaran Resort Hotel San Diego, CA
Pages:	798 - 803
Cite this article:	Chang, Chieh-Fu, Yang, Ru-Muh, Kao, Ming-Seng, "Implementation of an Innovative Phase Discriminator for Improved Tracking Performance in One-Bit Software GPS Receiver," Proceedings of the 2008 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 2008, pp. 798-803.
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