Measurement of spurious-related errors on commercial wattmeters

A procedure for the estimation of digital-wattmeter sensitivity with respect to the presence of spurious components in the acquired signals is proposed in this paper. The procedure allows an analytical estimation of such a sensitivity to be obtained if the spectral-analysis algorithm of the wattmeter under investigation is completely known; otherwise, an experimental estimation is required. Two different procedures are proposed: one approach can be used if the wattmeter is used on an FFT algorithm, while another longer procedure is able to characterize any kind of wattmeters. Both experimental procedures can be performed by employing a simple test-set, which is based on two commercial signal generators and on a Personal Computer