DEFECT DETECTING SYSTEM FOR MAGNETIC MEDIUM

PURPOSE:To realize the 100% detection of modulation of a high frequency with high accuracy and at the same time to improve the checking accuracy and the reliability of a magnetic medium by adding the waveheight values of each one round together for each designated numeric value and comparing these added waveheight values with those of the adjacent sectors. CONSTITUTION:The signal of a fixed amplitude is read out of a magnetic medium 1 by a magnetic head 2 and amplified by a reproducing circuit 3. Hen a waveheight value detecting circuit 4 detects the waveheight values D1, D2, D3 and so on. Each of these waveheight values is converted into the digital waveheight value respectively. These digital waveheight values are successively written into a memory 6 with the synchronization of a timing generating circuit 7. The circuit 7 adds those values D1, D2... together via an adder 80 for recording until a signal is sent to a memory 81 from the circuit 7. At the same time, the waveheight values DK+1, DK+2,... equivalent to (k) bits are added together by an adder 90 and recorded into a memory 91 at the time point when the signal is transmitted from the circuit 7. Then the total value of the memory 81 is compared with that of the memory 91. Thus it is possible to measure the characteristics required for a servo medium with high accuracy.