Co-channel interference effects in an HF data link

The high frequency data link (HFDL) waveform, defined by the ARINC Specification 635, is a new high frequency (HF) waveform that will soon be an important standard for both commercial and military aircraft data communications. The HF band is currently cluttered with many narrowband users, as well as several other noise sources. The proliferation of HFDL users will most likely make this situation even worse. As a consequence, understanding the interference environment and its effect on HFDL data communications reliability is of vital importance. In this paper, the effects of co-channel interference in an HFDL system are evaluated. Specifically, the paper contains descriptions of both the HFDL waveform and the HF channel. The interference effects are examined using measured data from previous experiments with an HFDL system. The interference under examination includes unwanted reception of voice and MIL-STD-188-110A single-tone waveforms.