| 摘要 |
PURPOSE:To reduce bus interference by temporally interrupting the output of a received voice signal in accordance with a specific period including a horizontal period in which a signal to be measured is inserted or the period longer than said period in the vertical blanking interval of the received video signal. CONSTITUTION:A demodulated voice signal Sa is supplied to a low frequency amplifier circuit 13 through a switching circuit 12 and the amplified signal is applied to a speaker 14. The circuit 12 is turned on/off by the control of a gate signal Pg applied from a gate signal generating circuit 15 to a control terminal 16 of the circuit 12. At that time, the circuit 15 detects a vertical synchronizing signal VSy of a video signal Sv from a video signal processing circuit 7 and generates pulse-like signal Pg with 3H amplitude which rises after 16H from the leading edge of the signal VSy and falls after 3H from the rise. The circuit 12 is off only in the period of the signal Pg and is on in other periods, interrupting the signal Sa temporally. |
