Resolution of multimoded HF transmissions using the DOSE superresolution direction finding algorithm

Attempts to use the MUSIC algorithm to resolve multimoded ionospherically propagated signals failed due to the lack of robustness of MUSIC. A new algorithm DOSE (direction of arrival by signal elimination) is described, and its effectiveness evaluated from measurements made on a seven element array for a number of European broadcast transmissions in the range 9-10 MHz. This new superresolution method is very much better at resolving multimoded HF signals than interferometry and much more robust than MUSIC. In all cases, it was found that DOSE was able to resolve the received multi-component wave-field into separate modes which agreed well with those expected from a consideration of ionograms for the same period