An experimental frame difference signal generator for the analysis of television signals

One proposed method of reducing the channel capacity requirements for the transmissionof television signals over long distances is known as frame difference signal (f.d.s.) coding. This method implies the recoding of television signals so that only those parts of every frame are transmitted which are different in two consecutive frames. In order to assess the possible savings in channel capacity resulting from this technique, it is first necessary to measure and record the probability density of f.d.s. areas in actual television programme signals. In this paper an f.d.s. generator is described which, by using a vidicon camera tube as storageand subtracting device, produces frame difference signals suitable for of statistical analysis.The generated signals are further processed to obtain the frame by frame integral of the f.d.s.areas, and the ancillary equipment required to carry out this operation is described. The data are recorded for subsequent evaluation.