Performance degradation of PN matched filter with clock frequency offset and its compensation
Takaaki Hasegawa, Masao Nakagawas · Electronics and Communications in Japan (Part I Communications) · 1987
Abstract One of the important problems in the spread‐spectrum communication system is the despreading of the received signal in the receiver. The CCD delay‐line matched filter is a kind of device realizing the despreading. It has a problem in that the sampling frequency must be exactly the same as the clock frequency of the spread signals contained in the received signal. When there is an offset between the two frequencies, the performance of despreading is degraded in the delay‐line matched filter. However, for this problem, no quantitative analysis has been made so far. This paper presents a theoretical analysis by the new method and under several assumptions, for the degradation of the peak output in the CCD delay‐line matched filter when there exists an offset of the clock frequency. The results are compared with the results of computer simulation. Based on these results, a CCD matched filter loop is proposed which has the function to follow the various frequency offsets. Its performance is demonstrated by the simulation.