The Sound of ILR 

1 October 2018

From ‘Television and Radio 1977’, published by the Independent Broadcasting Authority in December 1976

The transmitters and studios of Independent Local Radio are among the most interesting examples of modern broadcasting technology to be found anywhere. When the original Sound Broadcasting Act 1972 (now consolidated into the Independent Broadcasting Authority Act 1973) reached the statute book, the IBA engineers were faced with building up to 60 new local broadcasting services. Yet the broadcasting frequencies were limited and, particularly on medium waves, already groaning under a vast overloading of stations. VHF/FM had been used in the UK for over 20 years, yet (despite the improved reception) was used by only a small minority of listeners. There were some, but relatively few, stereo broadcasts on the national networks – and none on the existing local radio stations.

Although radio had become less formal than the days when announcers, as a matter of course, wore dinner jackets to read the news and most of what was said on any programme was prepared in advance in the form of scripts, there was still relatively little access by the public: ‘phone-ins’ were rare, ‘vintage’ radio comedians had largely deserted the medium for television, teenagers had their own discs. It seemed that, outside of broadcasting, nobody cared very much what became of radio; though an occasional voice was raised saying how one missed using one’s imagination to supply the images and faces.

Across the Atlantic, radio broadcasters were forced to supplement their income by broadcasting subsidiary channels of background music to department stores and offices; the stations were often automated and lifeless; around our own shores the ‘pop pirates’ had come and gone, suggesting that there was still a latent interest in the sound of radio – if only it could be a lively, imaginative, interesting sound.

Technical Requirements for ILR

To IBA engineers one thing was clear. It was no good building a new system on the traditional lines of European broadcasting. The technology had not only to overcome the basic problems of overcrowding and high powers. It had also to provide high quality; a full commitment to stereo; vhf/fm that could be easily received in cars; technical facilities which would help the companies to achieve their aim of making themselves part of their own local communities by making it easy for the public to talk back. Nor should any automation rule out a ‘live’ and lively sound. And although impressive new purpose-built studio centres were not regarded as an essential prerequisite for the provision of good Independent Local Radio, the companies were expected to use the latest equipment and to build studios that did not pick up every passing aircraft or nearby power drill.

All ILR studios must conform to the IBA’s Code of Practice. Here Katie Glass controls the Radio Orwell desk during her Sunday morning programme.

Effective sound-proofing coupled with good acoustics breathes ‘life’ into the sound and reflects back on the presenters to a degree few realise. In dull or reverberant surroundings, disc jockeys seem to be riding tired nags.

The engineers tackled the transmitting problems by looking afresh at the technical side of sound broadcasting. They found that much of the standard work in this field in Europe dated back many years.

They drew inspiration from work done in the United States on complex multi-mast directional transmitting aerials. This would allow them to fit in stations all on the same 261 metre wavelength, but with different programmes in London, Birmingham, Manchester, Glasgow, Plymouth and Tyne/Wear. With this approach the serious shortage of medium-wave frequencies can be partially overcome (though little can be done about night-time interference from other countries).

To improve vhf/fm reception in cars and on portable receivers the engineers again drew inspiration from American practice. By giving their aerials ‘circular polarisation’ – making the electromagnetic waves travel outwards with, as the engineers would say, ‘constantly rotating electric vectors’ – they have made it possible to pick up stronger signals on rod and ‘whip’ aerials.

Every vhf/fm transmitter is linked with its local studio centre using high-quality stereo-capable music links, either supplied by the Post Office or using special IBA radio links.

Although the ILR stations are truly local stations and do not depend on ‘sustaining’ national networks for programmes, they are ‘linked’ to the studios of IRN (Independent Radio News) just off Fleet Street in London. The stations have a speech circuit to carry the hourly bulletins of national and international news and are also linked to IRN by teleprinter so that news stories can be prepared for local reading.

At the studio centres can be found special monitoring and alarm equipment that shows when any problems have arisen at the transmitters, where, incidentally, no staff is normally required. Each transmitting installation includes at least two transmitters so that a stand-by may be quickly brought into use if a fault occurs on the first.

The studio centres are skilfully arranged so that programmes can go out smoothly and professionally with a minimum of staff. It all looks very informal to the old-time broadcaster but those split-second jingles and commercials depend on the most sophisticated techniques that overlay a measure of ‘automation’ on an essentially ‘live’ performance.

Parliamentary Broadcasting

When in the summer of 1975 Independent Radio News participated in the experiment of broadcasting directly from the Chamber of the House of Commons, a special IRN/IBA technical unit was set up in a compact portable building providing some 20ft by 7ft 6in., including an interview area. All the necessary technical equipment was installed in just 13ft by 7ft 6in. of floor space – a tiny fraction of the space used by the other teams taking part in the experiment. As IRN’s Ed Boyle says: ‘We were fortunate in being such a compact and accessible unit. We slept on the premises. We worked hard. We were able to change our plans, to adapt to situations as they happened… our mode of operation – frenetic as it was at times – endeared us, I suspect, to many MPs. They could see we were trying’.

IRN’s portable caravan during the 1975 Parliamentary broadcasting experiment.

A sentiment that reflects much of ILR activities, not least its technical side. Trying hard, adapting to change – but above all using the latest technology with enormous professionalism, to produce a radio service of the highest quality.

Good listening to ILR

The Independent Local Radio programmes come from modern transmitters and modem studios, built and operated in accordance with a tough IBA Code of Practice. But to gain full benefit from these transmissions you need good receivers, sensible aerials, and a little knowledge of what contributes to good reception.

Advantages of VHF/FM

Real connoisseurs of good quality are advised, wherever possible, to use the vhf/fm service rather than medium waves. The use of vhf/fm gives a significant improvement: better fidelity; better dynamic range of sound; far less local electrical interference or interference from other stations, by day and night; and a constant level of reception, summer and winter.

The large number of stations, the effect of the ionosphere at night (which brings in distant stations) mean that it is not possible to provide high-fidelity broadcasting on medium waves. But medium waves do have some advantages: they enable simple receivers to be used and allow easier reception in cars. You do not automatically obtain ‘high-fidelity’ by listening to vhf/fm. It needs good quality loudspeakers and amplifiers and an effective aerial to do that. But vhf/fm usually gives lower ‘background’ noise and allows you to listen in stereo if you wish: something not available on medium waves.

All ILR services are broadcast from both medium-wave (mf) and vhf/fm transmitters. After dark the medium-wave service area may be reduced by interference from distant stations; in daytime, however, reception may be possible on some receivers well beyond the recognised service area. But remember, the ILR transmitters are intended to provide a local service.

A special feature of ILR vhf transmissions is the use of circular polarisation which makes reception easier for listeners with transistor portable sets and car radios (i.e., sets using telescopic or vertical aerials). Most domestic receiving aerials are horizontally polarised, but where a listener is close to a high-power horizontally-polarised transmitter which swamps his reception of the more distant or lower-power ILR transmissions it may prove better to use a vertically polarised aerial for ILR since this will discriminate against the strong unwanted signals.

Good Aerial and Earth for MF

For mf reception the importance of a good aerial and earth system is often overlooked and many listeners needlessly put up with electrical interference and other forms of poor reception. Many sets have built-in ferrite rod aerials which can help overcome interference from other stations by turning the set for minimum interference. On medium waves a good outdoor aerial and earth system will greatly extend the daytime range of a receiver.

Stereo Reception

ILR provides the only local stereo broadcasts in the United Kingdom and for most of the time the programmes are transmitted in stereo. Stereo represents a worthwhile improvement over conventional reception, providing the listener with an illusion of a ‘sound stage’. We can use our directional hearing and our ability to analyse sound to allow us to pick out and concentrate on individual instruments.

To receive broadcast stereo, like stereo tape and disc records, a dual-channel amplifier is needed and two loudspeakers. Also required is a ‘stereo decoder’ which is normally fitted as part of a stereo receiver.

A stereo signal occupies a wider channel; it is more susceptible to interference from other stations and needs a significantly stronger minimum signal than mono. It is usually no use making do with an odd piece of wire or an inbuilt set aerial: very often good ‘hiss-free’ stereo needs an outdoor or loft aerial with two (sometimes more) elements, properly installed. There are bound to be a few places, at the limit of the service area, where listeners can get satisfactory mono but just cannot get rid of all the ‘hiss’ on stereo without a very large aerial.

Domestic systems need to be correctly arranged to obtain full benefit of stereo. The two loudspeakers should be placed some feet apart, and the listener hears the correct stereo effect when sitting roughly an equal distance from the two speakers, with an unobstructed view of them.

Reproduction can be ’coloured’ by excessive reflections from walls and the floor. If possible the speakers should be raised from the floor, with heavy curtaining between the walls and the speakers and carpeting on the floor.

Sometimes it is easier to obtain good results by listening on modern stereo headphones; this retains the sense of spaciousness and the directional effects, although if a listener turns his or her head the whole sound environment turns.

Tune your receiver carefully, learn how to set the controls. The quality of modern radio reception is well worth the little extra trouble… particularly on ILR!

Your comment

Enter it below