Simulator testing of HF modems

The need for standardised testing of data communications waveforms, using HF propagation path simulators, has long been recognised. This need has been accentuated by the requirement for off-line testing of waveforms to enable the retention of user waveform performance information within the evolving automatic radio control system (ARCS). Additionally an urgent need was established to select a robust waveform for the transmission of internal ARCS information to enable the setting-up of links under very difficult propagation path conditions, to include those likely to be experienced by small platforms anywhere in the world. In order to fulfil these requirements, the NATO HF Communications Systems Group (HFCSG) progressively specified and agreed the series of tests, which are described. The results from the Doppler And Multipath Sounding Network (DAMSON) experiment, initially operating at high latitudes, are being used to establish the conditions prevalent in the auroral and polar regions, where some of the worst path conditions occur