The development of the Wireless Set No. 10: an early application of pulse-length modulation

The experimental development of the system is described briefly, being a historical record of the design of an interlaced pulse-length modulated, multi-channel telephone circuit, and its application to a centimetre-wave radio link. The multiplexing equipment, radio sender and receiver, and the complete station, are described. A more detailed account of the electrical and mechanical difficulties encountered in the production is given and, where relevant, a technical description of the various units is included. Where a variety of possible solutions to lesser known techniques were considered, reasons are given for the final decision. The radio-frequency technique was developed concurrently with the engineering of the equipment and, where applicable to the particular problem, is described in detail. A brief description of the complete station includes overall electrical characteristics, its limitations and the method of testing to ensure a uniformity of performance. A general description of the equipment in its final form has been given elsewhere.1