| 摘要 |
PURPOSE:To transmit data while a data bit is added to a voice signal coded bit by superimposing a single frequency signal on a voice signal from the transmission side, coding and transmitting the result and switching the code rule corresponding to the bit number assigned to the data after a prescribed time or the reception of a reply signal from the reception side. CONSTITUTION:A reception processing section 7 decodes a voice signal VS at the transmission side A and detects a single frequency signal. A data processing section 6 uses this detection signal to discriminate that the reception side B completes the preparation of reception, a signal BN commanding the bit number of data is fed to a bit number command circuit 4 thereby switching the coding rule of the voice signal at the coder 2. For example, in assigning 1 bit to the data, the coder 2 is switched with the coding rule coding a voice signal VS in 7 bits, 1 bit of the data DA is added by a transmission section 5 and the result is transmitted. A data processing section 14 gives a control signal to the bit number command circuit 13 at the reception side B and the 7-bit coded bit is decoded by the decoder 11 to be the voice signal VS and the 1-bit is outputted separately as the data DA for the command.
|
