Analysis of response of FM mobile receiver in quasisynchronous field

Frequency-modulated quasisynchronous (QS) mobile radio systems are of benefit to PMR users already committed to FM in the solution of radio coverage problems. The paper analyses the performance of a conventional FM receiver in the overlap area of two QS transmitters and gives graphs quantifying this performance as a function of system parameters. The paper suggests design criteria for a practical system and shows, on the basis of speech-intelligibility tests, that satisfactory performance of a QS FM system is possible throughout the coverage area, except at those pockets where the two received carriers have approximately equal strength. Here, a receiver modification is proposed which can result in marked improvement in the quality of reception.