Simulation of high frequency voice band radio channels

The fundamental purpose of channel simulators is to provide repeatable performance comparisons between particular equipment and associated configurations. An additional important role is to assist in the design of HF equipment. As the state of development of radio equipment improves, the accuracy of simulators used for this purpose becomes increasingly crucial. The authors commence with a critical review of HF simulation models and highlights their deficiencies. An alternative approach to employing a stochastic model to simulate the HF channel is to construct a replay simulator which can make recordings of the time-varying impulse response of test channels for later reproduction of on-air conditions in the laboratory. Some of the advantages of replay simulators are their high degree of accuracy and that results obtained have an absolute physical reference. The design of a replay simulator, nearing completion, is discussed. It is proposed that a standard recorded-channel data base be prepared which would facilitate the exchange of quantitative performance results and give modem designers a sound basis on which to optimize their designs