Cozi Oblique Incidence Ionospheric Soundings Using Normal Communication Transmissions

Oblique incidence backscatter soundings have long been used in probing the ionosphere. These have normally employed pulse transmissions and thus have required either special equipment, or special modifications to existing communications equipment for transmission and reception of such signals. A new technique has been developed which allows normal communication or broadcast transmissions to be used for backscatter sounding. It involves a cross correlation performed between the transmitted signal and the returned backscatter signal. The use of re-entrant delay lines as storage devices permits continuous real time cross correlations of relatively long samples of the waveforms. An A-scope presentation of the cross correlation function serves the same purpose as an A-scope display of the backscattered pulse signal. An intensity modulated range-time display of the cross correlation function, very similar to the range-time display commonly employed in ionospheric sounding, can provide a continuous record of skip distance variations. Samples of experimental data obtained using this technique are presented.