Sending transmissions 'down the line'

By request of old timer tvmercia.

Hello. Always wondered how exactly they do this. Sending live programming down the line from wherever the studio may be to the BBC, ITV, Channel 4 etc (incidentally, is C4's TX actually in Horseferry Road or off somewhere else now too?)

Would it be at all possible to feed a live recording 'down the line' from say one university to another so it could be edited in a different place after the actual recording is over and done with? Or would you need massive huge complicated facilities?

Also what are 4-wire circuits all about? Do they as I think maintain complete visual and sound contact between the programme gallery and the TX centre for most of the day of the rehearsal to transmission? So for instance if one studio fired up their 4-wire circuit back to Television Centre then the TX controller at TVC would be able to watch everything going on in rehearsals just like any normal viewer at home would be watching the telly, complete with gallery talkback perhaps?

Yes C4 is at Horseferry Road

There's many ways of doing it.

All TV stations and the larger studios/facilities houses have what are known as 'local end' connections to and/or from BT and are switched at BT Tower in London. If, say, channel 4 is broadcasting a programme from Teddington Studios; Channel 4 will book with BT to switch the local end coming out of Teddington into one of their incoming lines.

It could also be done by satellite with the uplink/downlink either being dealt with by the studio/station or a third party like Arquiva or Globecast

With the BBC they'll use their own contribution network to send programems from one place to another. i.e. they'll just book a line from, say, Glasgow to the Broadcast Centre in London (not normally direct, it'll be switched through several BBC centres). I believe ITV have their own dedicated network too.

A programme being broadcast on Channel 4 from a BBC studio would go down the BBCs network, out from TV Centre to BT and then on to C4

Often (particually with major prime time programmes) stations will book a reserve circuit too in case the main one is lost. So there might be the same programme being fed via BT and via satellite or in the case of the BBC via 2 diffrent routes of their network or one via satellite



It's possible, all you'd need is a connection between the 2 that's capable of sending video. Unless they could somehow dig up all the roads and lay a wire between the two (unlikely and very very expensive) they'd have to use a 3rd party company such as Colt, Globecast, BT, Arqiva etc. Even then they'd have to have cables in the area.

Although these days you coudl send video fairly easily and cheaply down a broadband connection



A 4-wire circuit carries 2-way talkback and nothing else.

For a programme broadcast you'd usually book or set up lines carrying video, audio (sometimes the audio and video are combined together - embedded audio) and talkback. The TV station would have a 'co-ord' phone number too so they can speak to the other end without the need for talkback.

If it's an insert for a programme (a line carrying a guest that's being interviewed for example) you might not have talkback, you'd have a 'clean feed' or an 'ifb' (interruptable fold back) instead - this is programme sound minus the audio from the source. They might also book return vision so the remote studio could see what's happening on the programme

Normally a TV station wouldn't book a line from the source too far in advance. The line would normally cost money and resources are finite so you don't book them out for longer than needed.

Normally you'd have the line up from the studio anything from 30 minutes before the on-air time, known as 'line-up' time. This is where line up takes place - the TX controller and engineers checking that the picture sound and comms with the studio are all ok and to confirm on-air time

You really are a font of information Inspector, thanks a million for all of that. I take it you must work / have worked in transmission at some point?

I think I'm right in saying this is how the BBC used to operate some of its London outposts, places like the TV Theatre. VT was handled at TV Centre rather than on-site.

I see, thank you Steve. Any idea how it is done to build on what has been said above?

Not much more I can add to what the Inspector has said really Mark. For the University to University example the IP option is worth investigating given that Universities are linked on JANET which is a pretty fast network.

Many years ago I did, I still work in the world of lines and satellites though.

I see, no worries. Does sound interesting...

I see, it does sound like a very interesting world that. Pretty exciting having that much control too I'd imagine. Some more than a production team in a way because you're actually controlling whole channels!

So with JANET would all you need be your basic computer and internet connection? How would you be connecting the output from your gallery transmission to the internet connection? Sorry for the long questions...