Performance Study of Reduced Search FFT-Based Acquisition

Phani K. Sagiraju, David Akopian, and G.V.S. Raju

Abstract:	With the improvement in accuracy of Global Positioning System (GPS) receivers and operational capability in different environments, many new applications emerge which rely on GPS. Central to all the operations of the receivers, is signal acquisition and tracking, which is the capability of the receiver to perform a successful search of available satellites and extract ranging measurements. During acquisition the whole goal is to acquire the information regarding the residual frequency modulation and the misalignment of received signal in terms of code phase as quickly as possible. To achieve this goal in real time, acquisition is to be carried out by fast techniques such as Fast Fourier transforms (FFT). Although FFT based acquisition techniques accelerate computations they still perform many redundant operations in environments such as indoors or urban areas where some sort of assistance might be available. This is because they search over a maximum number of code phases in the availability of assistance. Recently authors introduced the idea of reduced-search frequency domain massive correlator which resolves this problem. A penalty of slightly reduced correlation peak (3 dB in sensitivity) is introduced due to reduced search specific to this approach. In this paper we target the peak degradations that are caused due to reduced-search frequency domain approach. We present a new enhancement based on our previous analytical assumption on how to minimize the peak degradation. We then study the performance of the new method to that of our previous method and summarize the effects of it. We finally present a way in which the reduced search FFT method is implemented to have improvement in both peak degradation and performance.
Published in:	Proceedings of the 2007 National Technical Meeting of The Institute of Navigation January 22 - 24, 2007 The Catamaran Resort Hotel San Diego, CA
Pages:	153 - 160
Cite this article:	Sagiraju, Phani K., Akopian, David, Raju, G.V.S., "Performance Study of Reduced Search FFT-Based Acquisition," Proceedings of the 2007 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 2007, pp. 153-160.
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