Study of Delay-Delay Rate 2-D Correlation in Satellite Observation of VLBI

Due to the self rotation and revolution of the earth and the satellite moving comparatively, the delay rate changes intricately and that affects correlation result when we use VLBI to detect Satellite. To solve the problem, a new method of delay-delay rate 2-D correlation is proposed which based on time-frequency 2-D correlation. This method applies ambiguity function calculation of time-frequency analysis theory to VLBI. The result of Doppler shift equal to the product of delay rate and the frequency of satellite transmitted was proved in this article, so the method of delay-delay rate 2-D correlation is put forward refer to the theory of time-frequency 2-D correlation, and this method can get the value of target's delay and delay rate by peak value search after ambiguity function calculation of two stations' received signal. Simulation results have indicated that this method can detect value of the delay and the delay rate at the same time, and it's useful for VLBI to detect Satellite.