Fault detection in video disc recordings - identifying type of error by comparing half pictures by processing in digital logic circuits

摘要

The fault detector is partic. for mass produced video recordings on discs on which there are two half pictures per disc revolution. An error recognised in one half picture is compared with error signals in the following 2n half frames, where n is zero or an integer. The detected errors are processed in digital logic circuits and resolved into single isolated faults in one line, faults affecting two lines in the same position on the disc, that is in two consecutive pictures, scratches affecting larger numbers of pictures, and signal failures due to faulty recording or disc reproduction resulting in 'drop-outs'. Faulty recording or reproduction is recognised if errors are detected in successive half pictures. The synchronising pulses for the error detection system may be obtained from the recorded picture synchronising data.