| 摘要 |
PURPOSE:To eliminate an unpleasant sound from a speaker due to an automatic transmitter recognition signal by entering muting operation during the reception of the automatic transmitter recognition signal by the bit or frame synchronism detection output of the automatic transmitter recognition signal from a decoder part. CONSTITUTION:Data such as a voice and an automatic transmitter recognition signal received by a reception part 20 are amplified by an amplifier 24 and outputted to a speaker 22. A demodulator 25 demodulates a 1,200Hz and a 1,800Hz frequency signal to input values ''1'' and ''0'' to a decoding part 26. The decoding part 26 detects synchronizing bits from serial data of ''1'' and ''0'' and generates a detection output at the point of time when a synchronizing bit is detected. The output is passed through an OR circuit 21 to turn off a switch 23, and the amplifier 24 and speaker 22 are disconnected to prevent the automatic transmitter recognition signal data from being outputted from the speaker 22. Therefore, the unpleasant sound from the speaker 22 is eliminated. |
