Ground-based vertical-incidence ionograms

Radio Techniques for Probing the Terrestrial Ionosphere

“…Figure 3.12 shows the NOAA HF Radar AIS system and Figs.3.13-3.15 are block diagrams of this system and illustrate one particular research organization's design philosophy for an AIS system. This was a logical extension of Cohen's "flexible sounder" concept and Wright's Dynasonde, to ... A parallel development of another AIS employing a different design philosophy also took place during the late 1960's and 1970's at the University of Lowell in Massachusetts, and has been reported by BibI et al (1970) and Phillips (1974). This was a logical extension of Cohen's "flexible sounder" concept and Wright's Dynasonde, to ... A parallel development of another AIS employing a different design philosophy also took place during the late 1960's and 1970's at the University of Lowell in Massachusetts, and has been reported by BibI et al (1970) and Phillips (1974).…”

A pulse synthesis technique for improving ionosonde resolution

“…Since then the potential accuracy of such measurements has been pointed out by Whitehead and co-workers [ Whitehead and Malek, 1963;Whitehead and Kantarizis, 1967]. Recently digital ionosondes have been developed which routinely measure the phase (as well as many other properties) of ionospheric echoes [ Wright, 1969;Phillips, 1974]. Such systems, therefore, in fact record the information which is needed for the pulse synthesis technique presented here.…”

A reliable ionosonde for continuous automatic operation

“…The vertical pointing, sweep-frequency HF radar, or ionosonde, has remained the basic instrument for ionospheric observation ever since its introduction more than 40 years ago by Gilliland [1933] (see Phillips [1974]), and ionosondes of the IGY era (International Geophysical Year, 1957-1958 continue to be used today in much of the worldwide synoptic observing network. In 1967 when we were seeking ionosondes for continuous, unattended operation in a close-spaced network of stations for the study of TIDs (travelling ionospheric disturbances), we had one of these IGY instruments (the Canadian LG-17 which is very similar to the American C-4), but found it altogether too ponderous and unreliable for such operation.…”