Multi-dimensional HF modem performance characterisation

A high frequency (HF) communications system designed to service modern information exchange requirements can have at its disposal a variety of data modem configurations for supporting traffic transfer. These may vary in terms of user data rate, modulation and error control coding. Coupled with a choice of communications channel, this presents a number of possibilities for conducting a communications link at any particular time. To optimise system performance, with the aim of maximising user data rate and link availability and minimising link setup times, a channel and modem configuration should be selected and appropriately matched for each link to provide the best solution under prevailing channel conditions. This process requires an appreciation of the variations in performance, and hence the relative merits, of the modem choices on offer. This paper describes a technique which is under development and permits characterisation of modem performance across a range of possible channel conditions. Consideration is given to the suitability of using this information in a channel and modem matching process