| 摘要 |
PURPOSE:To prevent the malfunction due to crosstalk from a recorded signal of PCM postrecording to improve the reliability by turning off a circuit, which generates a detection signal of recording tape speed discrimination, during the PCM postrecording period. CONSTITUTION:A reproduced pilot signal PBPLT extracted from a reproduced signal by an LPF is sent to a gate circuit 51 of a recording tape speed discriminating device 27. The circuit 51 is turned off by the gate pulse, which is outputted during PCM postrecording period and indicates the PCM postrecording period, and does not transmit the reproduced pilot signal damaged by the crosstalk from the recorded signal. Meanwhile, circuits succeeding the circuit 51 are in the state of no signal during the PCM postrecording period, and an output signal FWR of a full-wave rectifying circuit 55 is dropped out to generate erroneous discrimination; and therefore, a sample and hold circuit 56 is provided between the circuit 55 and an LPF 57 to hold the signal, and the dropout of the signal FWR is compensated to prevent the malfunction, thus improving the reliability of discrimination.
|
