| 摘要 |
PURPOSE: To enhance the reliability of the apparatus by detecting the difference of period between adjacent measurement read clocks and comparing the difference of period with a predetermined threshold value thereby detecting erroneous read-out of a recorder/player. CONSTITUTION: An n-bit counter 4 receives a basic clock of predetermined frequency being generated 3 and counts the basic clock. A measurement read clock period pulse is cleared by a delayed 8 signal and fed to a latch means 5. Output from the means 5 is latched by a latch means 6. The means 5, 6 are fed with a clock, i.e., the measurement read clock period pulse, and the means 5 latches a new period data A whereas the means 6 latches a previous period data B. A processing means 7 determines a data (A-B) and operates the differenceΔT between the new period of the measurement read clock period pulse and the previous period. A CPU decision means 2 compares the differenceΔT with a predetermined threshold value to decide whether a read error is present or not.
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