Radiometers

The Advanced Communications Technology Satellite propagation experiment was designed by NASA to study the effects of precipitation, primarily rain, on Ka frequency band signals. Two beacon signals, transmitted from the satellite, provide attenuation data that is recorded by a propagation terminal located in Tampa, Florida. The received beacon data contains a DC bias and diurnal effects and is therefore uncalibrated. Radiometers, centered at each beacon carrier frequency, are used to set the 0 dB reference level for the beacon data, using constants determined through radiometer calibration techniques. The details of this process are examined using actual propagation data.