Calibration of Impulse Generators by Using Dicke-Type Radiometers

Impulse generators are not conventional instruments and present their own calibration problems. A new method for calibrating the output spectral density level of impulse generators is explained. A Dicke-type radiometer is used for measuring the equivalent noise temperature of the output power spectral density which can easily be converted to the spectral density (amplitude). The switching sequence of the radiometer should be synchronized with the impulse generator in order to have all the impulses delivered to the receiver. This method eliminates the need for computing impulse bandwidth and the need for measuring bandpass characteristics of the receiver. It also does not require a sophisticated radiometer but a simple Dicke radiometer. An impulse generator with 50 pulses per second (pps) rate is calibrated with a Dicke radiometer with a square wave switching sequence of 400 Hz. There is reasonable agreement between the calculated and measured values.