What is an Ionosonde?
“Quite generally, ionosondes are radars. In fact, the idea to use radio pulses for ‘detection and ranging’ was conceived for the purpose of measuring the height of the ionosphere in 1925, by Gregory Breit and Merle Tuve. The principal components of any radar must include circuits or devices which (a) define the signal to be transmitted; (b) amplify the signal to a useful power level; (c) radiate (as antennas) the signal generally upward and accept the downcoming echoes; (d) ‘receive’ the signal (or ‘echo’), by appropriate amplification, filtering and noise- rejection; (e) record the echo information in some suitable form. Unlike more familiar radars, the ionosonde does not attempt to direct its “beam” to locate its “target”. On the practical side, forming such a beam at medium and high frequencies (1 – 20 MHz) would be prohibitivly expensive; it would also be ineffective, since (like the sea surface) the ionosphere is continuously tilted, wavy and irregular: these properties, and not the direction of a beam, determine the location (or locations)from which reflections occur. Ionosonde antennas illuminate the “whole sky”.” (NOAA, 1.)
- “Frequently Asked Questions.” Dynasonde FAQ | NCEI. N.p., n.d. Web. 11 May 2017. (https://www.ngdc.noaa.gov/stp/IONO/Dynasonde/whatis.htm)