Elimination of False-Locking in Long Loop Phase-Locked Receivers

Although long-loop phase-locked techniques are finding increasing application in the fields of mobile radio and satellite communications, their use has several drawbacks. Time delay associated with filtering processes within the loop gives rise to a degradation in acquisition capability, and information components entering the control loop cause a reduction in adjacent channel performance. In this paper, a split-loop technique is described, which eliminates false-locking, substantially improves the acquisition characteristics to that associated with a loop with zero time delay, and "cleans up" the first local oscillator spectrum. Furthermore, the technique is simple to implement.