A modular testbed for automatic channel selection, link establishment and maintenance

The paper describes the development of a testbed radio system for automatic channel selection (ACS), automatic link establishment (ALE) and automatic link maintenance (ALM) techniques. As HF radio systems become more automated, the concept of ALE has evolved to describe the start-up phase of communications. ALE involves the co-ordination of channel encoding and decoding, encryption and decryption, frequency management and system control in order to meet specified user requirements. The most common requirement is a reduction in the level of operator expertise necessary to operate the radio system successfully. The purpose of ACS is to provide a quality analysis of the available channels, to enable the most suitable to be used for communications. Once a radio link has been established it is sensible for the system to employ ALM techniques to maintain the link in the event of interference or channel degradation.