Rapid capturing method for high-dynamic and low-carrier-to-noise-ratio signals

Abstract

The invention particularly relates to a method for quickly capturing high-dynamic and low-carrier-to-noise-ratio signals, which comprises the following steps of: preprocessing input digital intermediate-frequency signals, performing correlation operation on stored local pseudo code data and baseband data after down-conversion, and accumulating correlation results of which the length is a set value; if the local code phase is aligned with the pseudo code phase modulated by the baseband data, a peak value is obtained through FFT, the index of the peak value indicates the Doppler frequency, and the number of FFT calculation times indicates the code phase; calculating a module value based on a real part and an imaginary part output by the FFT; judging whether capturing succeeds or not based on the maximum module value, and obtaining the Doppler frequency of rough capturing if capturing succeeds; and refining the roughly captured Doppler frequency to obtain a refined Doppler frequency. According to the method, the Doppler frequency and the code phase are accurately searched in a short time, and the method is suitable for capturing high-dynamic weak signals.