In this paper, a practical model for evaluating and comparing the bit error rates(BERs) due to adjacent channel mutual interference in a synchronous and asynchronous frequency hopped spread spectrum multiple access(FH-SSMA) radio communication systems is proposed. After implementing the actual FH radio in both the sychronous and asynchronous case, the BER is computed and measured. An experiment of this system in mobile tactical environments reveals that the performance in the asynchronous case is lower than that of the synchronous case. The computer simulation model is an efficient tool for designing practical FH radios in mobile communication environments.