Recollections of BBC engineering from 1922 to 1997
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Designs Department - Special Studies Section




In 1964, the “Natlock” system of video signal synchronisation was developed by a team led by JLB.  This system enabled video signals from sources remote from a production centre to be synchronised with those from sources local to that centre.  The synchronising pulse generator at the remote source was controlled by means of coded error signals sent from the mixing point.  The error signals were derived by comparing the timing of the video signals from the remote and local sources, and the timing at the remote source was adjusted by digital methods in discrete steps too small for their effects on the displayed picture to be observable.  This use of digital methods rendered the behaviour of the system independent of normal variation of component values and, within wide limits, of the characteristics of the error signal circuits, which could be of telephone grade.  The system operated over long distances and an unlimited number of remote sources could be used.

Designs Department designed a range of Colour Natlock equipment in which the error signals control the sub-carrier phase as well as the timing of the remotely originating signal.  Its first large-scale use was at the investiture of the Prince of Wales at Caernarvon in July 1969.

Standards Conversion

After four year’s work, an electronic standards converter was brought to a successful practical realisation and demonstrated to members of the EBU Colour Group in 1963.  This converter was intended to provide a feed of BBC 1 video signals to 405 line standards when the BBC 2 service was introduced and most programmes were originated to 625 line standard.

In 1967 a field store standards converter, designed to convert the 60 fields/second American video signal to the 50 fields/second signal of European television was introduced.  The equipment was colour capable, and its availability made possible the provision of coloured pictures from the 1968 Olympic Games.  For the production of this device, the Queen’s Award to Industry for 1967 was granted jointly to Designs Department and Research Department.

In 1972, the growing use of digital techniques led to the development, by CD, of a new standards converter which operated on signals in digital form.  Such signals, being considerably more robust than analogue signals, could be handled by electronic equipment of conventional layout and construction (as opposed to the special arrangements necessary in earlier standards converters) and processed with increased reliability and greater consistency of performance.  The method lent itself well to the generation of additional lines in the video signal by the combination in varying proportions of information from the existing lines between which the interpolation is made, this process being inherent feature of standards conversion.

Electronic Character Generator

Among the more interesting achievements of 1970 was the development of Electronic Character generator equipment, popularly known as “ANCHOR”.  This enabled captions consisting of upper case letters, figures and punctuation marks to be super-imposed on a television picture.  The captions were composed at a keyboard or reproduced from punched tape or the store of a computer.  The special feature of the equipment was that the characters produced were of conventional appearance and not of the distorted shape commonly associated with electronic devices.  In 1972, the capability of the equipment was extended to the production of lower case letters.