| 摘要 |
PURPOSE:To execute the necessary measure such as the adjustment of a recording current by assuming a recording level from the envelope of a reproduced digital signal and generating the alarm of the deterioration of an over-writing characteristic. CONSTITUTION:A signal from other edge of a resistor 18 is stored into capacitors 22 and 23 through a switch 20, which is turned on during the pre or post ample period of a digital signal, and a switch 21 which is turned on during the data respectively, the stored signal is supplied to an arithmetic amplifier 24 and a difference component is removed. The signal of the difference component is supplied to a comparator 25, the difference component comes to be the prescribed size or above, and then, an alarm signal is outputted to an output terminal 26. The level difference of the envelope between the shortest wavelength part of the reproduced digital signal and the longest wavelength part is removed from the amplifier 24, and when the difference is increased to, for example, 2.5 times or above, the deterioration of the overwriting characteristic is judged and an alarm is generated. Thus, the measure such as the adjustment of the recording current is executed and the overwriting characteristic can be maintained. |
