The computer simulation of a high speed data transmission system for use over high frequency radio links

This paper is concerned with the serial data transmission of 9600 bit/sec over a HF radio link and the performance of a serial modem measured in terms of its error rate. Initially a model of a synchronous serial QAM digital data transmission system, which includes the model of the HF link, is presented suitable for computer simulation. A model of a near maximum likelihood detector, based upon the reduced state Viterbi algorithm, operating together with a predetection filter and an adaptive HF channel estimator, is described. Computer simulations have been carried out to show the performance of the complete system (in terms of bit error rate), in the presence of intersymbol interference and additive white Gaussian noise. The modem is a digital signal processor performing computer-like operations on sets of numbers