| 摘要 |
<p>The invention concerns a method and apparatus for detecting noise in an electrical signal. The invention is of particular application to the detection of noise in an electrical signal which represents an input video signal. The input signal is subjected to a frame delay and the absolute difference of each frame compared to the succeeding frame is derived by a difference circuit. The absolute difference signal from the difference circuit is sampled and the samples are applied to four comparator gates each of which selects samples having a signal level corresponding respectively to the gate. The outputs from the gates are counted in four accumulators which correspond respectively to the gates. The accumulated count values are supplied to a microprocessor which fits a probability density curve to the count values and determines whether a local maximum exists in the curve within a selected range of signal values. The presence of such a local maximum is indicative of the presence of noise in the input signal.</p> |
