Apparatus for adjusting a digital signal which is subjected to analog processing after being reproduced from a record medium includes a digital test signal source, a loop including DAC and ADC for circulating the digital test signal therethrough a predetermined number of times, a detector for detecting...http://www.google.co.uk/patents/US5557417?utm_source=gb-gplus-sharePatent US5557417 - Multi-loop testing apparatus with means for adjusting a reproduced video signal
