R&D Report 1964-58 : Review of television standards conversion A.V. Lord, E.R. Rout
In this report the basic functions of a standards converter are considered and the essential processes are discussed in some detail. It is shown that those problems encountered when conversion involves a change in the number of lines per field are essentially similar to those posed by a change in the number of fields per second. The established methods of standards conversion are surveyed in the light of these arguments. Almost all present-day converters rely on the 'image-transfer' method; the fundamentals of this process are described, and various techniques used for conversion involving a change of field frequency are discussed. Some limitations of present-day image-transfer converters are outlined, and possible improvements are considered. Recently, other approaches to the problem of standards conversion have been investigated. An outline of these mentions the application of magnetic recording and the use of lumped networks as storage devices. The design of future standards converters will naturally be dependent upon requirements. Mention is made of their present-day use in the Eurovision network and, in conjunction with video-tape recording and communication satellites, to facilitate programme exchanges between Europe and North America. The concluding discussion deals with the role of standards conversion in the future development of television networks; consideration is given to problems posed by dual-standard operation and the exchange of colour programmes with North America.