Development of a new controller for absolute cavity radiometer for cavity calibration and solar irradiance measurement

In this paper development of a fully automatic controller for absolute cavity radiometer is reported for self-calibration and measurement of solar irradiance using Eppley AHF cavity. The main component of the controller is a data logger CR6 from Campbell Scientific and utilizes some unique features of the logger. The computer program can be developed to make manual, semi-automatic or fully automatic measurements on given time interval with minimum input required from the user. In this report measurement with Eppley cavity is reported but the controller can be reconfigured to use any absolute cavity. The resolution and accuracy of the voltage measurement on the CR6 logger easily satisfies the WMO classifications of a pyrheliometer to be a standard reference.