In this paper, a new receiver for a frequency-hopped multilevel FSK system for mobile Communications is presented. This new receiver provides an implementation advantage by eliminating unecessary energy detection of all the frequency channels. A performace analysis of the proposed system is carried out by using the union bound. We show that an optimim number of message bits that minimize the word error probability exists for a given number of simultaneous users. This scheme is a generalization of the MFSK system that allows the message bits to be uaried, making it possible for designers to increase the flexibility of implementation. Error probabilities are calculated in the case of fixed bandwidth and fixed tone repetition number. The effect of using error-correcting coding is considered.