| 摘要 |
PURPOSE:To prevent a video signal from deteriorating in quality by transmitting a specific code from a transmission side in a synchronizing signal period, by resetting a forecasting circuit, and then by resetting a forecasting circuit at a reception side in the detection period of the specific code. CONSTITUTION:A video signal from input terminal 1 has the synchronizing signal separated by synchronous separating circuit 8 and in the synchronizing signal period, an input to forecasting circuit 6 is set to a constant value by the separated synchronizing signal to reset circuit 6, thereby exercising control so that the output of code converting circuit 5 will be a specific code. At the reception side, word synchronizing circuit 18 detects the specific code sent from the transmission side to attain word synchronization. The output of series-parallel circuit 11 is reversely converted by code reverse converting circuit 12 to restore the same signal of quantizing circuit 4 at the transmission side. Pattern detecting circuit 19, considering specificcode reception to be in the synchronizing period, generates an output resetting forecasting circuit 14 and this output and the output of D/A converting circuit 15 are applied to synchronizing signal adding circuit 16, so that the original composite video signal can be obtained from terminal 20. |
