Operational HF DF systems employing real time superresolution processing

Work on superresolution DF began at Roke Manor Research in the early 1980s as an extension to adaptive array research. For many, however, an awareness of the term superresolution DF began with the open publication of the MUSIC (multiple signal classification) algorithm back in the mid 1980s. Since this time the subject of superresolution algorithms (and maximum likelihood algorithms) has attracted intense interest in academic circles and vast quantities of papers have been published on an equally considerable range of different algorithms. Each invented algorithm purports slightly improved performance be it better DF estimates, better resolution, better sensitivity or simply more elegant mathematical matrix manipulations. However, despite this vast quantity of published theoretical analysis and computer simulation results on superresolution DF, there has been very little reported on practical results and next to none on fully operational DF systems employing superresolution DF. This paper aims to start to redress the balance by describing the hardware system and DF performance of an HF operational superresolution DF system