| 摘要 |
PURPOSE:To digitize the detection processing and make adjustment unnecessary and to enhance the degree of tolerance to noise by collating a digital pattern, to which the waveform of a reproduced signal is converted in an A/D converting circuit, with a standard pattern to detect the signal. CONSTITUTION:The waveform of the reproduced signal which is applied to the input of an analog-digital converting circuit 4 is converted differentially to a binary digital signal by a delay device 8 and a comparator 7. This digital signal is converted to parallel data by a series-parallel converter 9 to obtain a digital pattern P corresponding to the input signal. This digital pattern P is sent to a pattern collating circuit 5 and is compared and collated with standard patterns Qj. They are compared with each other in the collating circuit 5, and a code Mi corresponding to a standard pattern is outputted as the detection result. Differential conversion is used in the analog-digital converting circuit to enhance the degree of tolerance to noise having low frequency components, and standard patterns are selected to cope flexibly with the influence of peak shift and the variance of characteristics of a recording medium. |
