| 摘要 |
PURPOSE:To obtain a circuit with high S/N with simple constitution without characteristic deterioration by making the ratio of a time constant of a de- emphasis circuit to a time constant of a pre-emphasis circuit nearly equal to the converting ratio of a time axis converting circuit. CONSTITUTION:The time axis expanding device 40 is constituted by connecting a pre-emphasis circuit 41 and a de-emphasis circuit 42 before and after a conven tional time axis expanding device. The emphasis band of the circuit 41 is set nearly equal to the emphasis band of a de-emphasis circuit 25 and the pre- emphasis circuit 21 of a recording/reproducing device 20. Further, a time con stant tau41 of the circuit 41 is set equal to a time constant tau21 of the circuit 21 and the time constant tau42 of the circuit 42 is formed to be the relation of tau42/tau25=Ke>1, where Ke is a time expanding ratio of the expansion circuit 32 and tau25 is the time constant of the circuit 25. Since the effective band width of the devices 20, 40 is matched in this way, the output signal S/N of the device 40 is improved. |
