| 摘要 |
PURPOSE:To obtain a high privacy call effect with simple circuit constitution by repeating compression/expansion, modulating a voice and transmitting it from a master set. CONSTITUTION:A voice input signal is applied with five-stage of compression and expansion during a period of 3.33 millisec and modulated in a BBD circuit 107 of a master set 100 at first, and the result is transmitted to a telephone line as an output signal A. The signal A received by a slave set 200 is given in a BBD circuit 208 driven by the same clock pulse as a control clock pulse of the master set 100, the signal compression and expansion similar to that of the BBD circuit 107 of the master set 100 is repeated and demodulated into the original voice signal. Similarly, the voice uttered from the slave set 200 is modulated by the operation of the BBD circuit 214, transmitted to the master set as the output signal B, and the master set 100 demodulates the signal into the original voice signal by the operation of a BBD circuit 114. |
