Design concepts for a wideband HF ale capability

The recently promulgated US military standard MIL-STD-188-110C contains an appendix (Appendix D) defining a new family of wideband HF data waveforms supporting bandwidths from 3 kHz to 24 kHz in increments of 3 kHz. This family of waveforms extends the high performance serial tone modem technology of the MIL-STD-188-110B standard to wider bandwidths and much higher data rates, allowing users the option of selecting the bandwidth and modulation so as to optimize modem performance under the prevailing HF channel characteristics. However, fully realizing the potential of these new waveforms will require enhanced capabilities in other elements of an HF communications system, notably including a new `Fourth Generation´ (`4G´) Automatic Link Establishment (ALE) capability. This paper discusses requirements and design objectives for such a 4G-ALE technique, sketches some candidate 4G-ALE design concepts, and reports early results from on-air testing aimed at verifying the suitability and feasibility of these design concepts.