THE LAUNCH OF VHF-FM TRANSMISSIONS FROM THE WROTHAM SITE
How the BBC Plans to Develop the VHF Service
By HAROLD BISHOP, Director of Technical Services
The official opening of the VHF station at Wrotham, Kent, on Monday, marks the first step in the realisation of the BBC's plans for developing this new method of sound broadcasting in. this country It has long been clear to us in the BBC that some effective means must be found to overcome the serious deterioration in reception that has been caused by interference from foreign stations on medium wavelengths. Many expedients have been tried. and are still being tried, to overcome the interference. But the number of stations in Europe has almost doubled since 1950, and as a result the medium-wave band is far too crowded to permit good reception of the three BBC programmes throughout the country. This means that in many areas the Home Service, especially in a large part of Wales and in South-East England, is spoiled by foreign interference and there are no wavelengths available or additional medium wave stations. Moreover. because several stations must share one wavelength, some listeners receive a Home Service programme intended for some Region other than their own.
Now, after a delay of some years caused by the understandable reluctance of the Government to sanction substantial capital expenditure during a period of acute economic stringency, the VHF system has become a reality. It will give interference-free reception of the three sound programmes to very many listeners who have not had it before. Not only will it get rid of the bugbear of foreign interference, but it will greatly reduce interference from electrical appliances, which is especially troublesome in large towns on the long wavelength used by the Light Programme.
From Monday, some thirteen million people in London and the south-east of England within fifty miles or so of Wrotham will be able to receive the Home, Light, and Third programmes on VHF. Many of them will find it worth while to buy a receiver incorporating the VHF band, or an adaptor to go with an existing receiver. Apart from the virtual elimination of interference, an improved standard of quality is available on VHF because the receivers do not have to cut out the higher notes in order to reduce interference from other stations. Of course, the quality will depend on the receiver, and the cheapest cannot be expected to be as good as the more expensive in this respect. Listeners near the fringes of the service area would be well advised to use outdoor aerials, but many others will find that aerials built into the receivers, will be satisfactory. VHF receivers and adaptors are now on sale in the shops.
The First Ten Stations
What of the rest of the country? Wrotham is one of ten VHF stations all to be completed by the end of 1956. Three of these will, we hope, be in service and one partially in service by the end of this year. The first priority among these has been given to the one at Pontop Pike in North-East England, because it will enable VHF listeners to hear the North of England Home Service and items of local interest, instead of the combined Northern Ireland and North of England programme which they have received for many years from the transmitters at Stagshaw and Scarborough. This VHF station will serve some three million people. Next will come Divis in Northern Ireland, giving similar programme freedom there, and then Meldrum near Aberdeen. Between them these two stations will serve another one-and-a-half million people. Also before the end of 1955 we hope to bring VHF to Wales, which has suffered much from the interference on medium wavelengths, especially during the past year. The station at Wenvoe will serve over two million people in South Wales; the transmitter for the Welsh Home Service will come first and the other two early in 1956.
The other stations in the first stage will be North Hessary Tor (South Devon), Sutton Coldfield, Norwich, Blaen Plwy (Cardiganshire), and Holme Moss. These first ten stations will together serve eighty-three per cent of the population of the United Kingdom. In addition, a temporary transmitter is being installed in Anglesey to improve reception of the Welsh Home Service in a populous part of North Wales, pending the completion of a permanent three-programme station there under the next stage of the plan; this temporary station will not affect progress on the main scheme and will be ready towards the end of this year.
In deciding where the first group of stations was to be built, the competing claims of all parts of the United Kingdom were carefully weighed. Further developments, to cover other areas, and the rate at which they can be introduced depend on the approval of the Postmaster-General. The BBC hopes to provide about nine more stations by the end of 1957 others later, bringing the total VHF coverage to ninety-eight per cent of the population within the next four years.
There will still be a few areas, mostly mountainous districts with scattered communities. that may not be adequately served. They will not be forgotten, but it will not be easy to provide them all with a service or. the VHF systcm - which is not so well suited to mountainous country. When all the present plans have been completed, we shall be able to decide what remains to be done and how best to do it.
Finally, I must make it clear that in providing this new service ice we are not taking anything away. The existing long and medium-wave transmissions will continue for many years side by side with the VHF transmissions.
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