| 摘要 |
PURPOSE:To shape stably and exactly a waveform by sampling a tracking error signal by a field period, and inputting a sample holding output to a hysteresis comparator. CONSTITUTION:A reproducing pilot PL signal inputted to a mixer 3 through a BPF1 is mixed with an injecting PL signal from an injection oscillating circuit 3, 16kHz and 46kHz of its beat component are detected by detecting circuits 4, 5, respectively, and detected outputs are inputted to a comparing circuit 6. By a switch 7 controlled by a head output switching pulse RF, an output of the circuit 6 and its inverted output are selected alternately, a continuous tracking error signal is led out, and it is held in a sample holding circuit 9. The output signal of the circuit 9 is inputted to a hysteresis comparator 10, compares with positive and negative threshold voltages VE, VL applied by an inversion switch 12 in said comparator, and the compared output is varied stably by a prescribed period and inputted to a discriminating circuit 11. In the circuit 11, its period is counted by a pulse RF, and a recording mode is discriminated. |
