Spectrally efficient oblique ionospheric sounding

Presents details of research and concepts that have been developed within the Communications and Signal Processing Research Consortium at the University of Hull and University of Leeds aimed at providing an embedded ionospheric sounding capability that would exist as a normal function of an adaptive HF radio terminal. The authors describe a segmented swept FM (SSFM) sounder which operates beyond line of sight (BLOS) and is substantially more spectrally efficient than conventional LFM sounders currently used by NATO (chirp sounders).