1997: Adaptive Detection of Code Delay and Multipath in a Simplified Gps Signal Model

This paper introduces an application of adaptive filtering in a noise-canceling configuration that detects code delay and multipath in GPS using a simplified GPS signal model. An adaptive filtering process which allows a receiver to accommodate for changes in the environment surrounding the antenna is used. In this algorithm, filter weights from an LMS adaptive noise-canceling algorithm enable the receiver to determine the code delay from the 569 direct satellite signal as well as the delay and attenuation of the multipath. A simplified signal model which includes idealized GPS C/A-code processing, multipath signals of varying delay and amplitude, interference of other C/A-codes, and quantization noise is used for the preliminary demonstration. Plans for application of this technique to a more realistic GPS signal model and assessment of the computational requirements are also discussed.