Weak signal acquisition of high earth orbits based on new BAP method

In order to use GPS at the position of high orbits, it is necessary to research acquisition of weak GPS signal in the environment of high orbit. BAP (Block Averaging Pre-Processing) method is an effective algorithm to process weak signal, but it assumes that the receiver does work in the indoor environment with little dynamic effects. Based on the analysis of orbit parameters´ effects on the Doppler shift, this article concludes that it is necessary to improve BAP for using in the high orbit environment. From the offset compensation of code Doppler, calculated amount improvement of the algorithm, threshold value reduced, this article does further improvement to the BAP algorithm, making it suitable for high-orbit environment. Simulation results show that: Using of this improved algorithm can effectively reduce the algorithm´s acquisition threshold value, thus enhancing the ability to acquisition the navigation signals.