Method of detecting alterations in read out signals, and apparatus for implementing the same

Abstract From the Canadian patent

Abstract of the Disclosure, The present invention relates to a method and apparatus for detecting alterations in signals produced by the read-out of information recorded upon a data carrier The alterations, correspond either to an abnormally high frequency or to an abnormally low frequency. Detection is achieved by means of one, two or three monostable switching circuits supplied with trigger pulses originating from squared read-out signals. The defect signal produced by the last monostable switching circuit is used for controlling a defect correcting circuit.