Implementation of Code Tracking Loop using Narrow Correlator for GNSS

Abstract

The GNSS receiver processes the information transmitted by the satellites to decode the navigation message. The signals contain the spreaded code modulated with a high frequency carrier wave and to get the navigation data, the processing block needs to accurately tracks the phase of the incoming signal. Usually a delay lock loop with early-late spacing of 1-chip is used at code tracking stage but to have more precise tracking a narrow correlator is used which tracks with 0.1 chip accuracy. In this paper first basic working of code tracking loop is discussed, then the significance of narrow correlator is briefed. This paper focuses on the simulation results of both standard normal correlator and the designed narrow correlator. The design and simulation of code tracking loop is carried out in Xilinx ISE platform.