GNSS软件接收机中信号捕获新算法

利用频域圆周移位与时域载波剥离等价的原理,提出了一种新的捕获算法。通过对输入信号频谱序列的圆周移位操作,代替在不同载波Doppler搜索单元下对输入信号的重复性的载波剥离和FFT操作,在码相位和多普勒单元的二维搜索过程中,只需对输入信号进行一次FFT操作。新算法有效地缩短了捕获时间,且不影响捕获概率和捕获精度。实验结果证明,该算法可以正确地完成信号捕获,并节省了近50%的捕获时间。

A New Signal Acquisition Algorithm in GNSS Software Receiver

A new signal acquisition algorithm is proposed based on the principle that the circular shifting operation in frequency-domain is equal to the carrier wipe-off operation in time-domain.The repeating operations of FFT and carrier wipe-off in each carrier Doppler searching bin could be replaced by the circular shifting of the spectrum sequence of the incoming signal,thus the FFT of the incoming signal is implemented only once during the 2-dimension search of code-phase and carrier Doppler.With no degradation in probability and accuracy of acquisition,the new algorithm can significantly reduce the acquisition time compared with the traditional one.This algorithm has been implemented in the GNSS software receiver to acquire the raw GPS signal,experiment results show that the proposed algorithm can acquiste GPS signal correctly while reducing acquisition time by 50%.