| 摘要 |
<p>PURPOSE:To attain application of demand refresh by discriminating it to be occurrence of a transmission code error when a difference between a total sum of local decoding signals at a coder side and a total sum of decoding signals at decoder side is larger than a reference value so as to surely detect a transmission code error. CONSTITUTION:A total sum circuit 33 is provided, which fetches a local decoding signal (h) outputted from an adder 23 in a coder 10 and sums sequentially the signals as to picture elements of the entire pattern being an object of coding and sends a total sum (q) to a communication line 41 via a multiplexer/demultiplexer circuit 27. Moreover, a total sum circuit 63 is provided, which fetches a decoding signal (p) outputted from an adder 59 in a decoder 50 and sums sequentially the signals as to picture elements of the entire pattern being an object of coding synchronously with the operation of the coder 10 and sends a total sum (r). A comparator 65 takes a difference the total sum (s) with respect to the total sum (q) and the total sum (r) and when the absolute value exceeds a prescribed threshold value, it is discriminated that a transmission code error exists in the communication line 41 and a transmission code error detection signal (t) is used to communicate it with the coder 10.</p> |
