Abstract: A method of reducing the transmission bandwidth for television pictures is described in which the frame is divided into at least three fields each consisting of picture information from an apparently random distribution of picture elements and the transmitted signals are obtained by sampling the video output of a line scanned television camera as the scanning spot passes each of the picture elements. Usually no picture element will be sampled more than once during the formation of a complete frame and therefore each line scanning field contributing to the picture will consist of information from a different set of randomly distributed elements.

Abstract: A programmable keyboard of the kind in which a member presents a plurality of discrete areas to a co-operating probe, each of which areas produces a unique signal when addressed by the probe, is provided with a liquid crystal display to identify the current function of a particular area. Separate additional addressable areas are provided by means of which one of a number of alternative display functions can be selected as desired.