| 摘要 |
PURPOSE:To decode and reproduce automatically the signal which is encoded and recorded, by recording pilot signals for a prescribed period after the sound recording is started by means of a noise reducing circuit in a record mode and causing an automatic application of the noise reducing circuit when the pilot signal is reproduced in a reproduction mode. CONSTITUTION:The pilot signal is recorded on a magnetic tape 11 for a time T2 during which the muting of an input signal is released after a bias oscillator 13 starts oscillations after the sound recording is started. Then a pilot signal detecting circuit 16 detects the pilot signal in a reproduction mode. When the pilot signal is detected, the signal component is separated through an LPFa and rectified by a rectifying circuit (b). This rectified voltage is delivered in the form of an output signal of the circuit 16. An NR switch 18 of a reproduction system selects the output signal of a decoder 17 when the circuit 16 delivers an output signal and then selects the output signal supplied from a reproduction amplifier 15 when the circuit 16 has no output signal. Thus an automatic switch is carried out in a reproduction mode to supply an output to an output terminal 19. |
