| 摘要 |
PURPOSE:To detect an accurate peak position even to a read signal waveform of a magnetic disk device having a big level variation by using the comparison output obtained between a read signal and a signal obtained by delaying said read signal by a fixed period of time as a discriminating gate signal for peak position. CONSTITUTION:A gate signal generating circuit 8 supplies four comparison outputs SC-1-SC-4 to two inverters 81 and 82, AND gates 83 and 84 and an OR gate 85 respectively to perform the logical processing and produces a gate signal SG in response to the peak position of a read signal Sa. The signal SG is supplied to a peak discriminating circuit 11. While a differentiation circuit 9 differentiates the 1st delay signal waveform Sa-a, and the 5th comparator 10 compares the differential output with the zero voltage. At the same time, the circuit 11 produces a pulse signal which rises at the front and rear edge parts of the waveform of a differentiation/comparison output SC-5 by means of the signal SG. This pulse signal is equivalent to a peak pulse of the signal Sa. In such a way, the circuit 11 never produces an error pulse due to noises and produces only the peak pulse of an original signal. Furthermore it is possible to produce an accurate peak pulse even with a signal having a <=50% level. |
