| 摘要 |
PURPOSE:To improve the transmission efficiency by providing an amplifying circuit for amplification of a data MODEM transmission signal whose gain is so set that the peak value of the output is included at least in the linear area of the analog signal input conversion characteristic of a CODEC. CONSTITUTION:The gain of an amplifying circuit 20 is so set that the level of the transmission signal outputted from a data MODEM 18 set in the V. 29 MODEM function is lower than a maximum input level of a CODEC 13 by 6dB. Consequently, even the peak value of the transmission signal of the data MODEM 18 is linearly converted to digital data without distortion by the CODEC 13 as it is. Thus, data is properly transmitted without the occurrence of data error though the high-speed MODEM function of the data MODEM 18 is set in the V. 29 MODEM. |
