Abstract :
Two new developments in radio pulse sounding of the ionosphere are described with emphasis on some advantages available from modern digital techniques. The current stage of development of a digital ionosonde (dynasonde) is illustrated, showing the effectiveness of a simple logical process for distinguishing echoes from noise. Another digital radio-sounding system, including instrumentation (the kinesonde) and data analysis methods, has been developed to provide a statistical description of ionospheric motion and microstructure. From digital recordings of the time variation of complex echo amplitude at four antennas and six frequencies, a multidimensional correlation (correloid) analysis provides a profile of the three-dimensional mean motion, random (characteristic) velocity, shape, size, anisotropy, and lifetime of irregularities in the radio echo pattern; these irregularities can be related to their counterparts in the ionosphere.
