TV Breakdown Appreciation Thread

[Robertclark125]

It's changing the source output, like when TV-a, handed over to the regional ITV Companies, BT would change the output circuits, so that the TV-am feed was switched out, and the local ITV/IBA contractors feed was then switched in.

[Neil Jones]

In some cases it tended to help that the channels changing over were effectively 24hr streams in the first place - so the handover between Nickelodeon and Paramount at 7pm was quite sweet (and presumably the other way around at like 4am or whatever it was, the gap up to Nick starting at 6/7am being filled by a testcard of a giant chicken standing in the middle of a motorway (initially with test tone, later replaced with car horn noises)

The "phut" mentioned is very similar to how the analogue changeovers used to "appear" between TV-am/GMTV and ITV region at 6am/9:25am, and also 7pm (later 5:15pm) in London. on Fridays However the effects of that is exaggerated on video recordings and it wasn't anywhere near as bad a disturbance as the recordings would make you believe. I presume its a similar effect recording from analogue satellite, although the blip would have probably been generated on the digibox as your recording would have gone box -> video -> TV. Unless its digibox specific? But looks like a changeover of sorts on the transponder.

[Bennyboy84]

In some cases it tended to help that the channels changing over were effectively 24hr streams in the first place - so the handover between Nickelodeon and Paramount at 7pm was quite sweet (and presumably the other way around at like 4am or whatever it was, the gap up to Nick starting at 6/7am being filled by a testcard of a giant chicken standing in the middle of a motorway (initially with test tone, later replaced with car horn noises)

The "phut" mentioned is very similar to how the analogue changeovers used to "appear" between TV-am/GMTV and ITV region at 6am/9:25am, and also 7pm (later 5:15pm) in London. on Fridays However the effects of that is exaggerated on video recordings and it wasn't anywhere near as bad a disturbance as the recordings would make you believe. I presume its a similar effect recording from analogue satellite, although the blip would have probably been generated on the digibox as your recording would have gone box -> video -> TV. Unless its digibox specific? But looks like a changeover of sorts on the transponder.

Yes the Paramount/Nick handover was very clean indeed

https://youtu.be/mrKuH8_yKPY

[Robertclark125]

One fault in 1990, on Telethon, affected the regional round up, when Michael Aspel would go round the ITV companies. Twice, he tried to get an update from Nerys Hughes, and Arfon Haines Davies, at HTV Wales. Both times, they got pictures, but no sound. Accoring to the HHG website, there was something in the background, suggesting a network fault, than a fault at HTV Wales. They did get through third time lucky.

[Markymark]

One fault in 1990, on Telethon, affected the regional round up, when Michael Aspel would go round the ITV companies. Twice, he tried to get an update from Nerys Hughes, and Arfon Haines Davies, at HTV Wales. Both times, they got pictures, but no sound. Accoring to the HHG website, there was something in the background, suggesting a network fault, than a fault at HTV Wales. They did get through third time lucky.

ITV didn't use sound in syncs back then [1], so video and audio routing and the paths the two different circuits took around the UK were different. In fact video went largely between cities by microwave, audio by landline. There were plenty of places (both within ITV company studios, and BT) where the two could get accidentally separated.

[1] Although I think some companies used SiS internally. For instance Thames between Teddington and Euston ?

[Robertclark125]

This is the incident, which I believe happened during the first "round the regions" round up.

https://www.youtube.com/watch?v=YOObhDioozY

[Inspector Sands]

Not really breakdowns as such but does anyone know why in the days of when channels used to handover, sometimes they used to have static or other loud noises during the handover?

As seen here

https://youtu.be/j09TeoWq-QA

With the Quantum/Eurosport example it's because the two channels had different uplinks. This was analogue satellite so one channel per transponder.

In some cases like Nick and Paramount the changeover between the two was seemless because they came from the same place and same owners. Not the case with Quantum and Eurosport, they came from two different companies in two different countries and were uplinked from two different places.

So what you're seeing is Quantum ending and a satellite engineer in (presumably) the UK turning off the uplink, followed by a satellite engineer in France turning on their uplink to the same transponder. The static is the short bit where there's nothing on air. It needed to be done that way as you can't 'double illuminate' a satellite transponder so they're careful to make sure that one is off air before the other comes on air. I read somewhere years ago that it was all co-ordinated twice a day via a conference call between the two uplinks and Astra.


These days if two channels timeshare like thag then its done on a multiplex level, with one bit stream disappearing and another replacing it. The Big difference with that is that both have to be sent to the same coding/multiplexing facility, but these days that's fairly easy compared with having to rent full capacity video circuits as they would have to do in the 90s

[ElMarko]

Wouldn’t they have realised in the Telethon gallery there was no audio coming down the line before putting it to air?

[Robertclark125]

Wouldn’t they have realised in the Telethon gallery there was no audio coming down the line before putting it to air?

Well, according to this page, you could hear the groans from the gallery at LWT when the sound failed the second time. But as mentioned above, back then, video and audio routing used two different circuits, and so the audio circuit may well have been working fine, in the gallery, but when it came to putting it to air, things went wrong.

http://www.hhg.org.uk/bds.html

[thegeek]

So what you're seeing is Quantum ending and a satellite engineer in (presumably) the UK turning off the uplink, followed by a satellite engineer in France turning on their uplink to the same transponder. The static is the short bit where there's nothing on air. It needed to be done that way as you can't 'double illuminate' a satellite transponder so they're careful to make sure that one is off air before the other comes on air. I read somewhere years ago that it was all co-ordinated twice a day via a conference call between the two uplinks and Astra.

I've done that before, but with the main and backup versions of the same multiplex from different uplink sites under remote control. It's a bit nerve-wracking: dual-illuminate for too long and you could potentially damage the satellite, leave too much of a gap and you knock quite a lot of channels off air at once.

[Markymark]

So what you're seeing is Quantum ending and a satellite engineer in (presumably) the UK turning off the uplink, followed by a satellite engineer in France turning on their uplink to the same transponder. The static is the short bit where there's nothing on air. It needed to be done that way as you can't 'double illuminate' a satellite transponder so they're careful to make sure that one is off air before the other comes on air. I read somewhere years ago that it was all co-ordinated twice a day via a conference call between the two uplinks and Astra.

I've done that before, but with the main and backup versions of the same multiplex from different uplink sites under remote control. It's a bit nerve-wracking: dual-illuminate for too long and you could potentially damage the satellite, leave too much of a gap and you knock quite a lot of channels off air at once.

I'm not sure how you could physically damage the satellite by feeding it two beams on the same frequency? Physical damage to electronics can only be induced by something that overheats components and/or applies a higher voltage than the design is for, neither of which is possible from two beams that have travelled 23,000 miles, the signal is tiny, and received power is tiny. Satellites are at far greater risk from solar flares and other cosmic radiation

[Neil Jones]

Here's an interesting, not "breakdown" as such, more a case of the inexperienced running the machine in the days of TV-am's strike.

In this particular example they've managed to under run by an entire minute, cutting everybody off in the process and presumably in a panic throw the presenter back on air and leave her to crash into the 9:25am handover relatively messily with only the clock for company.

Oh and they manage to generate a non-sync cut as well bringing in the eggcups.

https://youtu.be/W05bFZdDR2w?t=295
(from 4:55 onwards)

[Inspector Sands]

I'm not sure how you could physically damage the satellite by feeding it two beams on the same frequency? Physical damage to electronics can only be induced by something that overheats components and/or applies a higher voltage than the design is for, neither of which is possible from two beams that have travelled 23,000 miles, the signal is tiny, and received power is tiny. Satellites are at far greater risk from solar flares and other cosmic radiation

Hmmm, it's a threat I've heard as long as I've worked with satellites but how true it is I'm not sure.... and of course I don't want to try it to find out! I imagine there's an element of truth especially with earlier generations of satellites.

It's not the signal going up that's a problem, it's the one going down. The transponder takes incoming signals on a certain range of frequencies, shifts their frequency, amplifies them and then re-transmits them. So the more powerful the incoming signal the more powerful the one it's transmitting. If you're double illuminating you're shoving twice as much power into the transponder and that's being translated into a much higher transmit power coming down

Double illuminating a transponder could potentially have an issue with power across the whole satellite. Power levels on satellites have to be managed. There's only a finite amount of power to go round, if one transponder is suddenly requiring more power then that has to come at teh expense of the others. If you've multiple carriers on a single transponder, one that's been brought up a bit high will affect the levels of the others. That's one of teh reasons why satellite uplinks are lined/talked up by the satellite or space owner.


Something that is double illuminated would be a bit of a mess and potentially affect the other transponders and of course wouldn't be recievable, but would it actually cause damage? I'd have thought with modern satellites there's a level of protection built in. The transponders on high powered DTH satellites such as Astra have a fair amount of auto-gain* on them so presumably that would also limit exess power too.





*I have (intentionally) cut a carrier on Astra and immediately the transponder ramps up the gain on teh background noise trying to maintain the level of a signal that's not there any more. On a spectrum analyser it can look like you've not cut it at all

[Inspector Sands]

Here's an interesting, not "breakdown" as such, more a case of the inexperienced running the machine in the days of TV-am's strike.

In this particular example they've managed to under run by an entire minute, cutting everybody off in the process and presumably in a panic throw the presenter back on air and leave her to crash into the 9:25am handover relatively messily with only the clock for company.

Oh and they manage to generate a non-sync cut as well bringing in the eggcups.

https://youtu.be/W05bFZdDR2w?t=295
(from 4:55 onwards)

I seem to remember this being discussed at the old forum, including some chat about how come TVS started with a Channel 4 trailer.

As for the TVam clip, you'l notice that Jayne Irving is wearing a different outfit for the end (it's the same colour but different). What it looks like is that they were playing an old edition of After Nine due to the strike. So the bit up to and including the rogue eggcups is on tape, the wobbly jump cut into the egg cups is probably a crash record on the tape rather than a nice clean edit

They either mistimed that tape and got Jayne to fill or they were intending to stop after Mad Lizzie and Jayne was meant to do the closedown bit live but she had less time than intended.


A great clip all round really, TVS cramming as much into their first few minutes as they possibly can, and an episode of The Time The Place on something we all take for granted now and isn't even an issue, yet then people apparently got very angry about!

[thegeek]

Hmmm, it's a threat I've heard as long as I've worked with satellites but how true it is I'm not sure.... and of course I don't want to try it to find out! I imagine there's an element of truth especially with earlier generations of satellites.

likewise! I did think when I was typing that 'hang on, is that actually true' and realised that I had nothing to back that up. Perhaps it's an old wives' tale from my, er, more experienced colleagues.