Atomic clock error modeling for GNSS software platform

This paper presents satellite atomic clock error model for generating the satellite clock error in GNSS software platform for the GPS Ll C/A code signal, L2 civil signal, L5 signal, and Galileo El, E5a signals. Scheme to simulate the clock error through phase error characteristics of the atomic clock are given. Rubidium, cesium and hydrogen maser clock are considered for GPS or Galileo satellites and Quartz oscillator is considered for user receiver. The clock error consists of five typical noises such as white noise on phase, flicker noise on phase, white noise on frequency, flicker noise on frequency, random walk on frequency. The analysis software for the Allan variance, the Hadamard variance and the PSD (power spectral density) of the clock error is also included. The clock error model is implemented and its validity is analyzed by comparing with theoretical ones.