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The life and times of james Hart: his family, his music, life in Luton and his occasional escapes onto the internet.

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Friday, 10 October 2008

A visit to a World Service Transmitter site...

I was rather excited to be invited to an open day at a World Service shortwave transmitter site, run by VT Communications in the west of Dorset.

The arrangements were set; we were to meet at Waterloo by 8am, so I caught the 6.15 from the airport - far earlier than I normally depart, and before the rush hour traffic has had time to congregate. By 11 o'clock, and after a coach, train and brief minicab journey, I, and the rest of the delegates from across the organisation (including two with whom I work) had arrived. Rampisham Transmitter Site is - as the name suggests - near the village of Rampisham; we caught the train to nearby Crewkerne.

Rampisham Transmitter Site from above

Once we'd settled in, we were shown a presentation about the history of the place, what they do there and why, and then an explanation of DRM (Digital Radio Mondiale - the digital version of shortwave, and pretty breathtaking to listen to, since using decent compression they can squeeze quite a high quality signal into a tiny bandwidth) and the refurbishment of transmitters on the Ascension Islands.

Because most of the gathered delegates were technical sorts (often they have editors and studio managers to visit) there were some very in-depth questions and educational answers.

After lunch, we were shown round the transmission switch (an amazing matrix of large metal 'pipes') and the satellite downlinks, followed by a tour of the transmitter hall - ten enormous boxes, most of which whirred and buzzed. One of the transmitters, though, made a most unearthly sound - the audio from the transmission was being - I suppose - induced and demodulated through the high-powered equipment, as if trapped inside the cabinet alongside the lethal voltages within. Unfortunately there was a gentle breeze blowing inside the transmitter hall and I didn't put the muffler on the H4, so the best recording I got was a brief one:

The eerie sound of a transmitter at work...

transmitter-sound.mp3 (192kB MP3 @ 192kbps)

They have a combination of water-cooled valve and 'solid state' (transistor) modulators and amplifiers that create radio signals of up to half a megawatt each... some of them were out of service, with their doors open so that we could see how the 60 thousand volts that are delivered by the National Grid combine with the signals that are delivered by all sorts of organisations, from BBC World Service to the military to be sent to the enormous (100m tall) transmission aerial arrays and beamed thousands of miles to Africa, Russia and the Middle East.

The weather was, once again, spectacular for October; I had worn my fleece and winter coat on the cold, dark walk to the coach stop, but was in my shirt sleeves when we were taken to the mast field, and wore less than the sheep that were grazing underneath the vast collection of transmission lines and antennae.

All too soon - which was a bit of a shame, since we could have spent much longer there, but for the irregular train service on the nearby single track route - we had to head back to London and from there, home not too long after normal time.

I took lots of photos, though! The best are in the gallery, and there's a scattering below.

Posted by james at October 10, 2008 10:14 PM

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