| 摘要 |
PURPOSE:To detect a case where the retransmission is impossible for a data clock where a code error is detected by sending a retransmission data block with addition of a block discrimination code from the transmission side and discriminating said data block at the reception side according to the block number and the discrimination code. CONSTITUTION:When a check code comparator 10 at the reception side detects a code error of a reception data block, a retransmission request signal transmission circuit 9 sends a retransmission request signal to a public telephone circuit 7 via a modulation/demodulation circuit 8. A retransmission request signal detecting circuit 6 at the transmission side detects said request signal. Then a transmission control part 2 reads the corresponding data out of a transmission data memory 1 and sends it again. A retransmission block discrimination code adding circuit 14 adds a retransmission block code to a retransmission data block, and a block number adding circuit 3 adds a block number preceding two steps. The retransmitted data clock passes through the comparator 10 as long as no code error is detected. When a block number detecting circuit 11 detects the same block number, a retransmission block discrimination code detecting circuit 15 decides whether or not the detected block is the retransmitted data block. |
