You searched for: “riometer
1. A relative ionospheric opacity meter which is a specially designed radio receiver for the continuous monitoring of cosmic noise.
2. An instrument that measures changes in ionospheric absorption of electromagnetic waves by determining and recording the level of extraterrestrial cosmic-radio noise.
3. A tool for measuring the electromagnetic capacity of the ionosphere using the strength of a cosmic radio source relative to that during minimums of ionospheric disturbances.