| 摘要 |
PURPOSE:To prevent a data signal to be transmitted later from being sent out from a transmission side by transmitting the data signal after a no-signal state for fixed time when the data signal is transmitted from the transmission side to a reception side, and stopping the transmission of the reception signal on the reception side when this no-signal is detected. CONSTITUTION:During a call between a radiotelephony set 2 and a called party side connected from a host equipment 1 through a wire line 3, when data transmission is executed from the radiotelephony set 2 to the host equipment 1, the some no-signal state is made by timer function previously provided on a control circuit 27 of the radiotelephony set 2 and afterwards, a transmission sound switch 38 is turned OFF at first. Then, a holding tone requesting signal made by the control circuit 27 is FM modulated and sent out through a transmitter 22. The receiver 10 of the host equipment 1 demodulates the reception signal. At this time, a noise detecting circuit 41 detects a noise level in the no-signal state and when the noise is caused by a data system, a signal showing the state is applied to a control circuit 16 by a signal line not shown in a figure. The control circuit 16 turns OFF a reception sound switch 11 by this signal. Afterwards, the holding tone requesting signal as the data signal is sent from the radiotelephony set 2.
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