| 摘要 |
PROBLEM TO BE SOLVED: To transmit a distortion-free high-quality DTMF signal without transmitting a control bit specially. SOLUTION: On the transmitting side, a DTMF detector 13 judges whether every one frame is a DTMF signal or not. When it is a DTMF signal, the corresponding compressed data is selected from a DTMF coding pattern memory 14 which holds the information of one frame of various DTMF signal compressed in advance by a high-efficiency voice coder 12 to output the data to a digital circuit 16. On the receiving side, a DTMF coding pattern memory 18 identical to that on the transmission side is installed. When the compressed data inputted from the digital circuit 16 is a DTMF signal, the DTMF coding pattern detector 19 detects with which one among the DTMF coding pattern memory 18 the data is coincident and generates the DTMF signal corresponding to the coincident pattern by a DTMF generator 20. |
