A Study on the Direct P-Code Acquisition of Weak Signal

A new direct P-code acquisition method based on FFT is proposed. The main concept of this method is to divide the large time uncertainty into several small time bins. It can greatly reduce the amount of FFT by cooperating with the use of external memory and thus to realize various acquisition policy flexibly. The probability of detection and false alarm of non-coherent integration under low SNR are analyzed, a new detection method called "A+B" based on double detection is presented. Thus not only the performance of detection is achieved, but also the acquisition time is saved. The implementation of this method using ADSP-TS201 is provided. It is shown that direct P-code acquisition can be accomplished within 60s when the ratio of the signal and noise is -32dB and the time uncertainty is ±1s.