DESIGN OF A THERMAL WATTMETER IN THE AUDIO FREQUENCY RANGE

This paper describes the development of a system for the measurement of power in the audio frequency range. Flexible units operating with a strategy based on the evaluation of rms quantity by a thermal method have been constructed. For each unit of the set-up, measurements and a preliminary characterization have been performed. The main quantities to be measured are two voltages, difference and sum. The difference voltage has been evaluated by means a vectorial voltmeter, instead the sum voltage by means a rms voltmeter. The module of the voltage difference in the acoustic band seems to be lower than 10 mu V. Further investigation and results will be extended when all components of the measuring system will be employed together.