The Riometer-A Device for the Continuous Measurement of Ionospheric Absorption

A sensitive, self-balancing, noise-measuring equipment, known as the riometer, is described. This instrument has been designed for routine measurement of ionospheric absorption during the IGY, using the cosmic noise method. Application of this technique in the auroral zone has resulted in quantitative measurements of ionospheric absorption, even during polar blackouts. The riometer has the advantages over a simple total-power cosmic noise receiving system of 1) linear response to changes of input noise power, 2) high accuracy in the presence of narrow-band RF interference, and 3) good long-term stability.