Switching control to Birmingham

You may remember that once in a while, the BBC did a switching test overnight (different to the RBS test), where, for a fifteen minute period overnight, a switch was thrown, and TCF on both BBC1 and 2 was replaced by TCG on BBC1, and an unlettered electronic test pattern on BBC2. These test cards were transmited from Birmingham.

The idea of the test was that in the event of something going wrong at TV centre in London, BBC network television would evacuate to Birmingham. A switch would be thrown, putting Pebble Mill in control of the network, where they would then attempt to run as normal a service as possible.

The test described above proved the facility worked.

It did happen for real in 2000, during Euro 2000, but what I was curious to know was, when the switch was thrown, what happened regards playout of programmes? I'm thinking here things like Eastenders. If Birmingham was in control of the network, how did they play out a scheduled programme?

The other thing is, when control was switched back to London, was it done mid programme, or in between programmes?

They used to do tests early on Sunday mornings with a "BM" bug added to Ceefax and other output to show it was passing through Birmingham.

Deejay of this parish can give chapter and verse on how Pebble Mill was able to run a makeshift service from its various galleries and edit suites. It was very Heath Robinson.

Switching back mid programme wouldn't be a problem, with the "proper" suite picking up the output of the temporary facility as an outside source, being put into circuit and mixing away at the appropriate point.

I actually happened to be up the night they did those tests (completely by co-incidence!), and I have recordings of those test cards on tape!

'In control' is probably the wrong phrase. The idea was that the source of the two channels was switched so they came from Pebble Mill, they didn't 'control' anything as such.


As for scheduled programmes, well I'm sure I can go into the procedure now as it's been over 10 years since it was a thing....
Those on shift at the time put the rest of the days tapes (or clone copies) into bags, got into cars and drove up the M40 to Birmingham. Hopefully they got there before the playout automation in TVC either ran out or the power went off. Of course before they left they had to make sure there were no live events left in the schedule - otherwise there was the risk that at 1 o clock BBC1 would cut to a shot of a news studio on fire

There were some standby programmes in Pebble Mill that could be played if they needed to, they were what you saw during Euro 2000..... although in the end that night everything stayed running at TVC, it was just a precaution

Wasn't the analogue system also set up so that each transmitter would rebroadcast a neighbouring transmitter and hence cover the country if the normal distribution system failed?

What is the setup now? Can the network be run from The Mailbox these days?

There is satellite back up if the feeds to a main transmitter fail. The disaster recovery location still exists, but it's not in Birmingham

The analogue network did indeed rely on a rebroadcast system

If you still have the tapes, is there any chance of putting it up on youtube and giving us the link?

During that 1997 test, the Meldrum Home Page suggests the Birmingham test cards (TCG on BBC1, an electronic test image on BBC2), were only seen from Crystal Palace, but does wonder if they were seen elsewhere. Were they broadcast on other transmitters?

There were no Teletext or PDC signals either during the test. But, what would have happened for real during the incident in 2000? Would teletext have still been broadcast?

Running the networks from Pebble Mill and rebroadcast standby are two distinctly separate things and not entirely linked.

If the presentation areas at television centre were evacuated but the rest of the building was still in operation, the first port of call was to move presentation to the post production centre in Stage V. A couple of VT booths, the off-tube commentary area and some edit suites could be reconfigured to provide presentation galleries. In theory, tapes could be left running in the pres area, and when PPC was ready could take them as an OS and be switched to air.

If the whole of TVC was out of action, Pebble Mill was the next port of call. News, weather and presentation could all be run from BM, using Studio A, Gallery A, the pres studio and various edit and VT suites. I've still got the documentation somewhere about who went where. It was rehearsed every so often and I seem to remember it all being a rather nice day out

Rebroadcast Standby was a system where if a transmitter lost its oncoming network feed, it would take the next nearest transmitter's signal and rebroadcast it until it's feed came back. The ultimate test (which was done overnight once a year until quite recently) was to take the feed to the network away from every transmitter except Crystal Palace. Each transmitter would then be forced to retransmit the nearest, so Crystal Palace became the source for a daisy chain of transmitter all the way up country.

RBS still exists for radio, I understand there was an overnight test last week.

Surprised they didn't bring the test forward before they did the NICAM coder swap to make sure RBS was viable if anything went pear shaped.

I do still have the tape, but I don't know if it's that interesting really- it's just the test cards you see on the MHP site with tones. I didn't actually record the switchovers or anything.

I would love to see some sanitised copies of that documentation if you ever find the time, Deejay!

I think it would be worth it, to show the "alternative" test cards that were being used, and to explain to people what was going on.

Do you know if teletext and PDC signals were being transmitted during that switching test?