| 摘要 |
PURPOSE:To set excellent equalizing characteristic automatically by detecting the 2nd harmonic of a repetitive signal during the recovery period of the repetitive signal and controlling the circuit constant of a waveform equalizing circuit in response to the quantity. CONSTITUTION:A signal 18 having the highest 2nd harmonic component in the reptitive pattern is inputted to a matching terminal (a) of a delay element 11 as a head amplifier output, a reflection signal is obtained from an open terminal (b), the sum is attenuated (12) to K/2 multiple, subject to differential amplification 13 and a corrected waveform equalizing signal is obtained. The signal is inputted to a BPF 15 via a switch 14. A gate signal controlling the switch 14 is generated only during the recording and reproducing section of the repetitive pattern 18 and the pattern 18 is inputted to a BPF. The center frequency of the BPF is twice the frequency f0 of the pattern 18. Then a DC level C in response to RMS is compared (21) with a level (d) of the reference 20 in the circuit 19 to control the attenuator 12 and the characteristic is fixed automatically to the equalizing characteristic with the set attenuation rate K and excellent reproducing characteristic is obtained even during the reproducing period.
|
