Automated HF data delivery utilizing real time frequency selection and adaptive data link protocol

The HF frequency band is well known for its many and varied disturbances and propagation difficulties. These effects combine to make the automation and control of HF communication systems very challenging. Many considerations exist for the automation of HF data systems including frequency selection and management, link establishment, voice and data delivery, and multistation network organization. Harris Corporation´s RF Communications Group has developed a prototype of an automated HF communication system that addresses these concerns. This system, the Advanced HF Data System (AHFDS), combines an easy to use operator interface, a new fast automatic link establishment (ALE) technique, and a data link protocol for error free HF data delivery. The operator interface provides message editing and scheduling capabilities. The fast ALE technique provides real time frequency management and selection. Error free data transfer is achieved by use of an extremely robust data transfer mechanism consisting of US MIL-STD 188-110A serial tone HF modems coupled with a newly developed data link protocol, proposed US Federal Standard 1052 (PFS-1052). The paper includes a discussion of automated HF system techniques, and an overview of the developed AHFDS prototype with special emphasis on the fast ALE technique. The important metrics for measuring the performance of automated HF communication systems are examined, the HF channel simulator and on-air performance results of the developed prototype system are presented, and the results of the prototype effort are summarized