The search range for GPS satellite signals varies depending on the receiver's startup method. In cold start mode, as the receiver has no prior information, it is necessary to reproduce the code and carrier signals of all GPS satellites in the sky, which is also known as blind acquisition of satellite signals. Under these conditions, searching for GPS satellite signals takes the longest time. In warm start mode, the receiver stores GPS satellite almanac data and approximate location information of the receiver. The almanac of a satellite can be seen as a simplified subset of its ephemeris parameters, with lower precision than the ephemeris. Its main function is to predict the approximate position of the satellite at a certain time and assist in capturing satellite signals. With the satellite's almanac data and receiver's approximate position, the approximate position and Doppler frequency shift of all GPS satellites at any time can be calculated, reducing the difficulty of capturing satellites. Under this condition, when searching for GPS satellite signals, the ground receiver only needs to search for up to 11 satellites, greatly reducing search time. In hot start mode, the GPS receiver stores the latest ephemeris data of the GPS satellite and more accurate position information of the receiver. Under this condition, the search for GPS satellites is very targeted and can quickly capture and track the current visible satellite signals, so the time to search for satellite signals is the shortest

Position calculation