The application of superresolution direction finding to a variety of channel conditions in the HF band

Direction finding (DF) of a radio signal involves estimating the direction of arrival (DOA) of signals incident at a receiver in azimuth and elevation. Superresolution direction finding (SRDF) algorithms have been developed which overcome the limits of resolution stated by Rayleigh, which implies they have the ability to resolve signals incident on an antenna array when their separation is less than the natural beamwidth of the array. In the HF environment this can be of great importance due to the small angular separation of some received signals, particularly if it is required to resolve different propagating paths from the same transmitter. This paper examines the application of several SRDF algorithms to various simulated channel conditions. In the simulation, parameters are chosen to be representative of conditions pertaining to reception of signals from a distant HF transmitter via ionospheric reflection. By employing simulated data, comparisons can be made for different fixed signal-to noise ratios and sample numbers, thus realising a representative repeatable simulation environment where the channel characteristics are known precisely. To complete the study the algorithms are also applied to real data