| 摘要 |
PURPOSE:To attain picture transmission even under a bad weather by applying data compression and convolution coding to a picture data an varying the data compression rate and convolution coding rate corresponding to the state of a transmission line with the combination in which the transmission speed is unchanged. CONSTITUTION:A digital video signal S1 is fed to a data compression circuit 12, a CRC code S3 for error check is added at a shaping circuit 13 and the resulting signal is fed to a convolution coding circuit 14. In this case, the data compression rate C and the coding rate R are revised according to the transmission condition and the coding rate R to obtain a required minimum coding gain is selected depending on the transmission condition thereby obtaining the maximum picture quality and avoiding the worst state of in operation due to rainfall. Moreover, the coding rate R and the data compression rate C are used as a pair, then it is not required to change the characteristic of the device, from a transmission circuit 15 till a reception circuit 22 against the transmission condition and the scale of the device is reduced. |
