Models of high frequency electromagnetic interference

Consideration of time-amplitude statistics of electromagnetic interference (EMI) is important in HF radio modem design. There are many models of EMI in the form of amplitude probability distributions (APD) functions describing the total time a signal envelope spends above a threshold. Other models describe higher-order statistics of the raw signal or its envelope. The models generally allow parameter extraction from measured EMI and enable performance assessment of radio modems using more realistic simulated channels. The literature on this topic however includes little on the higher-order statistics of EMI that characterise the impulsiveness of channels. More specifically, we wanted models to describe the statistics of the bursts in the EMI which are difficult to deal with in digital communications and are essential to consider in tests of radio modems using simulation tools. A study of existing models, model extensions and new models was undertaken. We discuss the use of models for characterising, modelling, and simulating EMI over voice-band (3 kHz) HF channels. We discuss the use of these techniques for testing and developing HF radio modems and show why existing modelling and simulation techniques are inadequate for these purposes