| 摘要 |
<p>PURPOSE:To detect a transmission error without extending code length and with a simple circuit by adding an address to the data in such a part where the level difference between an image signal from a frame memory and a currently inputted image signal is a threshold or above on a transmission side, then transmitting, and detecting a transmission error by using this address on the reception side. CONSTITUTION:Image signals divided into blocks by a pre-processing circuit 1 are subjected to the subtraction in a subtractor 3 together with the image signals corresponding to the same block of an already-transmitted picture that are stored in the frame memory 2. Thus obtained level difference is compared with a threshold output from a threshold circuit 4 by a comparator 5, when the level difference is larger than the threshold, it is multiplexed by a multiolexer 10 with the block address of image signals generated by an address generation circuit 6, then transmitted. On the reception side, the block address separated from the transmitted data by a data separating circuit 13 is checked by an address checking circuit 15, when the currently received block address in before the lastly-received block address, or when it is a block address that can not exist, it is decided to be a transmission error, hence the demodulation of received image signal and the transmission of the following image signal are controlled.</p> |
