Stochastic signal analysis system - operates by mixing test signal with standard search signal and evaluating difference frequencies produced

摘要

A method is used for determination of the frequencies present in a stochastic mixture. It depends on scanning the signals with a search signal of known frequency characteristics and analysing the difference frequencies produced in the scanning process. It finds particular application in the continuous monitoring of variations in the diameter or cross-section of a textile thread produced by a spinning machine. The output signal from a probe is fed to an adder (11) which also receives the output from an oscillator (15). The adder output is rectified (17) and smoothed and fed by way of a low pass filter (19) to a signal evaluator for frequency and amplitude analysis. A control signal is then produced at the output (22).