| 摘要 |
PURPOSE: To accurately detect line quality in a short time on a reception side and to change an information speed and an error correction coding rate while a transmission band width is fixed corresponding to the line quality. CONSTITUTION: On a transmission side 1, a digital encoder 11 for digitally encoding base band signals and varying the information speed based on the information of a noise power ratio transmitted from the reception side and an error correction encoder 12 for varying the error correction coding rate. In the meantime, on the reception side 2, digital modulation waves and reproducing carrier waves are multiplied in a multiplier 21 and converted to a base band, a signal level is detected in a reception level detector 23, the level of a certain signal component outside the base band is detected in a noise detector 25 respectively, the ratio of a carrier wave to noise power is calculated in a noise power ratio detector 26 and the data are transmitted to the transmission side by a transmitter 27. |
