Laboratory evaluation of a mobile radio data system

A mobile communications system has been built to study the parameters affecting data transmitted at 9.6 Kb/s over a laboratory simulated VHF mobile radio channel with additive white gaussian noise and Rayleigh fading. The signal is demodulated by a conventional mobile FM radio and its error distribution is recorded. The performances of different modulation schemes are presented and their BER are compared in a static and a fading environment. The simple and pratical technique of optimum threshold diversity switching by pre-detection of the signal´s envelope is used at the receiver to combat fading. The data sequences received are recorded and analysed by computer in order to determine the error distributions and the performances of BCH and Reed-Solomon error-correcting codes.