Design and Test Results of Software Based IF Level GPS Signal Simulator

摘要

This paper presents the design and test results of an analytical IF level GPS signal simulation software for SDR type GPS receivers. The developed GPS signal simulator is composed of two functional blocks: the first block for a navigation profile generator and the second block for a communication level signal generator. The user trajectory, satellite ephemerides, noise effect based on signal-to-noise ratios, final intermediate frequency, sampling frequency, quantization level of analog-todigital converter, and other environment parameters were considered to create valid IF level GPS signal components. Mathematical models were used to simulate IF level GPS signals for up to N-satellites in view. Based on user dynamic specifications, the update rates of a GPS signal parameters, such as amplitude, carrier phase, Doppler frequency shift, and code delay time are determined. rnThe previously developed multi-channel SDR GPS receiver software was used for the feasibility test of developed simulator software. The analytical IF level GPS signal simulator as well as the SDR GPS receiver covered in this paper was designed to evaluate various signal tracking methodologies without acquiring or simulating actual RF level GPS signal and subsequent processing for demodulation for up to high dynamic signal environment.