| 摘要 |
PURPOSE:To keep a desired line quality by using a ratio of noise power density to carrier power to detect the line quality and increasing the data transmission speed if the detected quality is higher than a prescribed line quality and reducing the data transmission speed if the detected quality is lower. CONSTITUTION:The output of a band-pass filter 4 having a band W through which a non-modulated carrier f0 passes is inputted to a wattmeter 5, and the output is inputted as data C to a processor 1 through an A/D converter 6. A band-pass filter 7 having the band W through which the frequency which does not include the non-modulated carrier and a carrier for data transfer permits the noise power of a reception line 10 to pass through, and the output of the filter 7 is inputted as data N from a wattmeter 8 to the processor 1 through an A/D converter 9. The processor 1 outputs a control signal 12 increasing the data transmission speed and a control signal 13 reducing the data transmission speed in accordance with carrier power data C and noise power data N to secure the communication quality.
|
