Sound signal correlation technique for quality control - detects and locates noises in motor vehicle rear axle or gearbox using statistical correlation of pick-up signals with reference

摘要

In the motor vehicle component quality control method, at least one oscillation pickup and a drive for rotating components are used. A reference signal is derived from the speed of rotating components and cross-correlated with a sound signal consisting of the sum of rotational speed harmonics and a wideband random interferences. Terms containing sum and difference frequencies are produced by multiplication. Only corresponding components are evaluated, and a display value is derived from them. The digital frequency divider includes a stage with two (J, K) flip-flops (20, 21) and three NAND gates.