| 摘要 |
PURPOSE:To obtain multi-value transmission with simple constitution and high reliability, by the automatic control of an AGC amplifying section so that a multi-value signal from a multi-value generating section is almost a constant transmission level independently of the change in the multi-value. CONSTITUTION:A multi-value generating section 1 converts binary information into a multi-value signal and can change the multi-value. The multi-value signal from the section 1 is applied to an AGC amplifying section 3 via an LPF2. The section 3 makes gain control with an average value AGC, for example. If inputted binary information is converted into a 6-value signal at the section 1 for output, and if the signal is changed to a 4-value signal through the deterioration of line condition, although the transmission level is lowered by 3.7dB, the control is made by the AGC function that the transmission level can almost be kept to the same level as the case with the level of the 6-value signal. At a reception side, the received 4-value signal is controlled so that the level is the same as that from the section 1, allowing to discriminate the 4-value signal through threshold levels TH1-TH3. |
