Performance Evaluation of a Differential Approach Based Detector

W. Yu

Abstract:	By implementing rigorous derivation analytically, this paper proves that differential combining (DFC) outperforms conventional non-coherent integration (NCH) in the detection of weak GPS signals. The processing loss induced by NCH can be decreased through the use of DFC by approximately 3 dB at low carrier to noise density ratios (C/N0). This improvement can halve the acquisition time, which is a substantial improvement in the context of weak signal applications. Monte Carlo simulation verifies the results obtained theoretically. Statistical properties including probability of false alarm and probability of detection are essential to set a detection threshold, which identifies a decision variable level (and corresponding signal to noise ratio) beyond which desired performance of acquisition and tracking can be achieved. Conditional probability density functions (CPDFs) of the DFC-based decision variable are necessary to analyze detector performance in a statistical sense, but are too complicated to express in analytical form. This paper, based on the statistical expectation and variance of the decision variable, uses curve fitting to approximate CPDFs produced by Montecarlo simulation. The results, although not strictly accurate, can provide a practical reference for the use of DFC-based detector. It substantiates that DFC is superior to NCH by improving the acquisition sensitivity by 1.2 dB to 1.6 dB, on condition that the probability of false alarm is fixed to 10-3 and the threshold of probability of miss is set to 0.1.
Published in:	Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006) September 26 - 29, 2006 Fort Worth Convention Center Fort Worth, TX
Pages:	2441 - 2452
Cite this article:	Yu, W., "Performance Evaluation of a Differential Approach Based Detector," Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006), Fort Worth, TX, September 2006, pp. 2441-2452.
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