| 摘要 |
A circuit for calculating a DC value for use in a code conversion apparatus of a recording and reproducing system includes a first storing element, second storing element, parallel to serial convertor, selecting circuit and a DC value calculating circuit. The DC value calculating circuit includes a load pulse generator for generating a second clock signal and a load pulse which is frequency-divided by a predetermined value according to a master clock signal; a counter for loading a reference value by the signal supplied from the load pulse generator, and counting up/down the serial data supplied from the parallel to serial convertor; a detector for detecting of whether or not the value counted in the counter is the same as the reference value; third storing element for holding a previous input value when the reference value is the same as the value counted in the counter, and storing the value counted in the counter when the reference value is not the same as the value counted in the counter; and a comparator for comparing the magnitude of the signal supplied from the third storing element with the magnitude of the reference value and supplying the result value as a signal for controlling the operation of the selecting circuit.
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