A method of obtaining fast response in solar pyranometers

The Absolute Measurement of Radiant Power

“…1.49c includes an input KC-filter for noise reduction (R 3 and C 3 ). It has a constant gain of Ri/R 2 at low frequencies, and in this circuit R 2 and C 2 should be selected so that R 2 C 2 matches the thermal time-constant of the radiometer (Brinkworth and Hughes, 1975). The function of the components R 1 and C x is to restrict the high-frequency gain of the circuit to avoid undue noise amplification.…”

“…Three examples of response-accelerating circuits. (Brinkworth and Hughes, 1975;Lilley et al, 1975) Many detector elements, however, do not show the same frequency response as the simple RC filter with lumped parameters, which has as its signature a high-frequency asymptotic slope of -20 dB/decade ( Fig. 1.48b).…”