Analysis of AM Phenomenon in GPS Signal

Abstract

When transmitting BPSK modulated signal, GPS simulator can be used to calibrate hardware delay under a wide variety of conditions by determine the average measured time difference between the one pulse-per-second (1 pps) reference and the bi-phase modulated code transition point. In practice, an AM (Amplitude Modulation) phenomenon rather than ideal BPSK modulation code transition point can be observed. Considering the structure of GPS L1CA signal, this AM phenomenon is analyzed by using Fourier series expansion, and serious impact of signal reflection on AM phenomenon is assessed by simulation.