Distortion measurement for FM transmission paths - using residual HF components of test signal applied to several selectors corresp. to discrete frequency values

摘要

A distortion measurement unit for f.m. transmission paths using the intermodulation method has a receiver in which the reference signal frequency is automatically tuned to the transmitted measurement frequency. The transmitted signal contains a 1.f. sweep signal and a higher frequency measurement signal. Residual h.f. components of the test signal are applied to several selectors each corresp. to a possible discrete frequency value, which generate switching signals to select the relevant reference oscillator frequency according to the signal frequencies occurring.