| 摘要 |
PURPOSE:To shorten an electrical transmission time for obtaining a clear recording picture, by optimizing a transmission speed automatically at every time according to the bit error rate of a transmission line. CONSTITUTION:On a transmission side, a picture signal from a picture signal generating circuit 10 which reads a transmitted original is encoded as prescribed and the resulting encoded picture data is stored in a code memory 12 temporarily. A code adding circuit 13 reads picture data out of the code memory 12 successively to section the data into blocks each consisting of a prescribed number of bits and adds a block number and an error detection code to each block to regard a prescribed number of blocks as a transmission unit, which is sent out the transmission line 30 through a modem 14. On a reception side, if a transmission error occurs after the picture data is received, an answer signal which contains its block number, request to resend, and information on whether a transmission speed is changed or not is sent back from a reception control circuit 25 through a modem 24. On the transmission side, the answer signal is received and the mode of the modem 14 is set according to whether the transmission speed is changed or not. |
