Automatically controlled HF radio systems-towards standardisation

Automatic systems of three types are discussed: automatic channel selection (ACS), automatic link establishment (ALE), and automatically controlled radio systems (ACRS). Traffic analysis results are presented and discussed for different systems: ACC (asynchronous common channels), SCC (synchronous common channels) SSCT (synchronous separate calling/traffic channels) and ASCT (asynchronous separate calling/traffic channels). Spectral efficiency and frequency allocations are discussed. It is concluded that the introduction of automatic HF Systems is better for the frequency utilisation of the HF band and that more work on the associated standards is required