AbstractThe land mobile communication is affected by fading when the mobile station moves in the multipath transmission environment. On the other hand, there are cases where there is no fading as in the communication with the standing or transported mobile station. It has been understood that the coherent detection using PLL is better in the nonfading environment and the differential detection is better in the fading environment.From such a viewpoint, this paper proposes a detector diversity system for mobile communication which can cope with the complicated states of the transmission path by switching between the coherent detection (PLL) and the differential detection using the error‐detection code. The proposed system uses a simple error‐detection code, and the two detectors are switched by selecting the detector with a fewer number of detected errors. The feature of the system is that it is simple, being constructed by the existing PLL and the differential detector. The effectiveness of the proposed system is verified by computer simulat