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BBC Engineering at War

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The BBC at War Engineering Contributions

By D.P.Leggatt

Thanks are also due to "L.G." Smith who passed the article on for publication on this web site.

Pat Leggatt held several senior posts in the BBC, including Head of Engineering Information Department.

Introduction

In common with all BBC staff, engineers contributed to wartime broadcasting with great dedication and ingenuity.  Virtually all emergency arrangements and expansion of services required very significant engineering work and development of new techniques which lay in the background of the events outlined below.  The valuable contribution to this wartime work by female technical assistants and operators is noteworthy.

Pre-War preparations

It was recognised early on that, in the event of war, radio broadcasting would be an important means of disseminating accurate news and emergency instructions, and of maintaining public morale.  But a difficult problem was foreseen in continuing broadcasting while preventing transmissions being used as navigational aids to enemy aircraft.

The solution was seen to be to operate several transmitters in groups all accurately tuned to the same wavelength, so that an aircraft could not distinguish one transmitter from another and hence could not 'home in' on any one.  Flight trials to test this solution were carried out as early as 1928.

In 1935 the Government set up a Broadcasting Committee to consider policy in time of war; and from 1936 the BBC put forward well developed engineering proposals for synchronised groups of transmitters, with approximately equal powers so that no individual one would stand out from the rest. BBC Research Department produced a series of very accurate and stable oscillator drives for synchronised transmitters, based on an excellent Post Office design of quartz crystal -- the device determining the transmitter wavelength.  These synchronising units were installed at the transmitters in 1938.

On the outbreak of war the plans were put into effect, consisting of one group of four high-power transmitters in England and Wales, and a second group of four in Scotland and Northern Ireland.  For effective synchronisation, all transmitters had to carry the same programme, so the existing National and Regional programmes were merged into a single 'Home Service'.  The Droitwich long wave 'National' transmitter had to be closed down since there were no other high-power long wave transmitters with which it could be synchronised into an anti-navigational group.

If an enemy aircraft approached within 25 miles of any transmitter it could have used the then stronger signal for guidance to the bombing target; RAF Fighter Command were therefore authorised to instruct the BBC immediately to close down the relevant transmitter.  Listeners in the area consequently lost their strong local signal, but could still receive a usable but weaker signal from more distant stations in the group on the same wavelength.

Although the Irish Republic remained neutral throughout the war, co-operative arrangements with the BBC enabled transmitters at Athlone, Dublin and Cork to be included in a synchronised group with stations in the west of England and Wales.

A little later, in 1940, the synchronised groups in the United Kingdom were re-arranged and enlarged; and an additional group enabled a second service, the 'Forces Programme', to be introduced. Yet another group of some sixty low-power stations was formed to maintain the Home Service when any of the high-power stations were put out of action by enemy raids.

In 1943 the BBC provided transmission and programme line facilities for setting up the 'American Forces Network'.

Studios and Lines

The B8C broadcasting headquarters was of course Broadcasting House in London.  Not only was BH the main studio centre for programme production, but it also housed the Control Room which formed the focal point where all studio and outside broadcast programme signals were fed in and then routed onwards to the transmitter network.  There was clearly a risk that BH could suffer bomb damage and an emergency Control Room was set up in the basement for use during raids when the main Control Room on the eighth floor was very vulnerable. Broadcasting House suffered severe damage from a bomb and a land mine towards the end of 1940, and Asa Briggs mentions the engineers' "superb job" in quickly restoring the equipment and cabling: no programme was lost, although programme control was transferred for a short time to the emergency centre at wood Norton described below.

For more complete security an out-of-London site was needed for an emergency centre, and wood Norton Hall near Evesham was acquired in the Spring of 1939.  Six studios were installed there by the outbreak of war to serve as a reserve production centre for the Home Service, when it was apparent that war was inevitable, an emergency Control Room was set up in record time by an Equipment Department engineer, L.G.Smith.

Music, Schools, Features and Drama Departments moved to Wood Norton on September 6th 1939; and a Monitoring Service reception station was established in huts in the grounds.  In 1940 a number of the Overseas Services Departments also moved there.  A pleasant story relates that Ralph Wade, Director of Office Administration, led an advance party to wood Norton in August 1939 in his car with secretary and typist and a substantial wad of money: it is said that he left London with 100 and 2 girls, and arrived with 2 and 100 girls.

Other programme dispersal studio centres had been established during 1940/41 in Bristol, Bedford and Bangor (north wales); and further studios in Weston-super-Mare were provided when Bristol suffered severe air raids. Additionally, about 150 small wartime studios sprang up all over the country.  A noteworthy studio centre in Bristol was that installed in the old Clifton Rocks funicular railway tunnel - carved out of the rock face of Clifton Gorge - with seven studios, several transmitters and self-contained power supplies.

All these emergency centres required extensive line (cable) networks to interconnect them, to feed programmes to the transmitter network and to provide teleprinter and other communications. Elaborate arrangements were made to ensure that alternative line routes could be established for immediate continuation of service in the event of air raid damage to any centre or line facilities.

External Broadcasting

External broadcasting expanded very rapidly to meet wartime requirements and many additional studios, control facilities and transmitters were needed. In 1940, Latin American and Near-East services moved to Wood Norton and the nearby Abbey Manor; and the European services moved to Bedford College in London. Other studios were developed at Aldenham and in part of Bush House.  As time went by, European services were concentrated in Bush House, and a new studio centre for the Overseas services was created in what had been part of Peter Robinson's shop at 200 Oxford Street (1941).

On the transmitter front there were two important requirements; first to increase the power and number of wavelengths of the European-services on medium wave in order to circumvent enemy attempts at jamming; and second to increase considerably the BBC's shortwave broadcasting to more distant countries.  Additional medium wave transmissions to Europe were provided initially by use of some of the former 'Regional' transmitters which had dropped out of use on formation of a single domestic Home Service.  The high-power long wave Droitwich transmitter was converted to medium wave and joined the European synchronised group.  Further high-power transmitter groups on other wavelengths were installed as time went by, including another at Droitwich with the exceptionally high power of 400 kilowatts: this latter was a major engineering innovation achieved by combining two lower-power transmitters in parallel, with each half pushed up to a higher power output than it had originally been designed for.

At the beginning of the war the BBC had only eight short wave transmitters, all at Daventry.  By the end of 1940 the total was increased to fourteen, and to forty three from six sites by November 1943.  As well as programmes originated by the BBC, 'America Calling Europe' was relayed from New York.

External broadcasting in the reverse direction was needed from D-Day onwards for relaying war news reports back to the UK.  A number of transmitters mounted in trucks for the BBC War Reporting Unit were transported across the Channel (and one to Italy), subsequently following Allied advances across Europe.

Monitoring

An embryo foreign broadcasting Monitoring Unit was set up at Wood Norton shortly before the war, although managed from London.  In 1940, following the bombing of Broadcasting House, the whole Monitoring Service was established at Wood Norton, with comprehensive communication links with London. Much engineering work was required in the way of providing the best possible receivers and aerial systems.

As more and more transmissions needed to be monitored, the accommodation at Wood Norton became inadequate and in 1943 the Service was moved to Caversham Park near Reading: the actual reception of signals was mostly effected at a special receiving station a few miles away at Crowsley Park where electrical interference was minimal, with the signals sent by line to Caversham.  The move to Caversham/Crowsley was accomplished with no interruption of monitoring activity.

A separate BBC technical monitoring operation was carried on at Tatsfield in Surrey.  Much of this work was concerned with accurate checking of transmitter wavelengths and identifying the location and nature of enemy jamming transmitters.  Another important contribution was the reception of despatches from BBC mobile short wave transmitters used by War Correspondents, and of programmes from the USA for onward relaying from BBC transmitters.

Recording

In the 1930's the BBC had made quite limited use of recording and at the outbreak of war had only eight recording channels, all at the Maida Vale studios, comprising two machines each for continuous recording.  At that time three types of recording methods were available; Blattnerphone and Marconi-Stille magnetic recorders using steel tape; Philips-Miller recorders which mechanically scribed a transparent track on blackened photographic film; and disc recorders using aluminium discs coated with cellulose lacquer, soft enough for a recorded groove to be cut but hard enough to withstand subsequent replay with a pick-up head.

A considerable expansion of recording facilities was needed, particularly for the External Services who had to cater for different time zones throughout the world. By 1945 nearly forty recording channels had been installed, mostly using American Presto disc machines obtained under Lease/Lend.

For use by War Correspondents, the BBC Research Department developed disc recording equipment robust and reliable enough for mobile use; although with a total weight of 450 Ibs it had to be vehicle-mounted rather than personally carried.  It was foreseen that war Correspondents would need a truly portable recorder and Research Department produced the Midget Disc Recorder by the end of 1943, which was to prove invaluable on D-Day and subsequent operations.  The Midget Recorder weighed only 35 Ibs, complete with batteries sufficient for recording forty discs before needing replacement.

Non-Broadcasting Contributions

BBC engineers co-operated with Government and Military departments on a number of counter-measures to enemy navigational systems and other activities.  One example was the operation of misleading beacons known as 'Meacons' which transmitted false information to interfere with enemy aircraft navigation signals from radio beacons in Germany.

The Alexandra Palace television sound transmitter was used with great effect, to jam another enemy aircraft navigational system known as Y-Gerat; and the vision transmitter was made ready, but not in fact needed, to jam German paratroop transmitters in the event of invasion.

An irritating nuisance in 1941 was the 'Mocking voice' injected by an Italian transmitter into intervals between items on the BBC Forces Programme.  This was countered by picking up the Italian transmissions at Tatsfield, scrambling the speech and radiating it from the Forces transmitters whenever the Mocking Voice appeared.  The nuisance ceased shortly after these counter-measures were introduced.

A special VHF transmitter and aerials were installed at Daventry in 1941 as the Eastern Chain master station of the RAF GEE navigational system.  The experience of BBC television engineers was valuable in this work since it depended on pulse techniques of the kind used in television.

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