Inspector Sands post_id=56984 time= user_id=1003 Wrote:nwtv2003 post_id=56981 time= user_id=1028 Wrote:Here’s an odd one from 30 years ago, Central hands over to TV-am and nothing happens until the white on blue caption gets put on air. I wonder whether the fault would have been exclusive to Central or whether it would have been networked. (From 31:55 in)
That's a good catch, interesting to see what Jobfinder was when it wasn't just teletext pages too
The blue and white caption is the one that appeared automatically when there was a lack of video. Presumably when there was no video signal they messed up the syncs which messed up the whole thing including the audio.
Could have been just one region or one transmitter or everywhere, unlikely we'd see another example from that morning to compare
As it happens after handover (via the infamous exaggerated "sync cut"), that suggests the issue is between TV-am and transmitter as it was outside of (in this case) Centra's control. But there is sound, so its not a total lack of connection to the transmitter.
Its very similar actually to this one from ten years earlier which was IIRC attributed to a vision desk failure:
https://www.youtube.com/watch?v=yODNh-ky-Fc
But the one on the TV-am clip says ITV, and not Independent Television at the top on the blue screen. That aside its practically the same message. IIRC when a transmitter lost video from the ITV company the blue screen always said Independent Television (and that remained the case for well into the days of NTL ownership?)
Neil Jones post_id=57067 time= user_id=961 Wrote:But the one on the TV-am clip says ITV, and not Independent Television at the top on the blue screen. That aside its practically the same message. IIRC when a transmitter lost video from the ITV company the blue screen always said Independent Television (and that remained the case for well into the days of NTL ownership?)
I've got the IBA emergency caption generator from Pontop Pike in my shed (Saved from a skip there just after DSO ) .
The PSU is dead, one day I am going to fix it, and I'll see whether that one says ITV or Independent Television (or it might say Channel 4) 50:50 chance which PIE rack it was ripped out of) !
Neil Jones post_id=57067 time= user_id=961 Wrote:As it happens after handover (via the infamous exaggerated "sync cut"), that suggests the issue is between TV-am and transmitter as it was outside of (in this case) Centra's control. But there is sound, so its not a total lack of connection to the transmitter.
Yes, they've switched the source from Central to TVam but it wasn't there.
I'm not sure what they used for distribution,was the sound seperate or was it SIS? The sound in those days was a seperate carrier, sometimes a seperate transmitter but presumably the receiver needed to be locked to the picture to lock to the audio
Quote: Its very similar actually to this one from ten years earlier which was IIRC attributed to a vision desk failure:
https://www.youtube.com/watch?v=yODNh-ky-Fc
Yes that occurred to me too
Could it be possible to switch sound, but not picture, from Central to TV-am at the local transmitter?
Inspector Sands post_id=57072 time= user_id=1003 Wrote:I'm not sure what they used for distribution,was the sound seperate or was it SIS?
It was DSiS, with the actual raw data within the sync pulses being the NICAM 728 stream. In other words, it was coded into NICAM at the studio, and decoded back to analogue in your telly [1]. At the transmitter the NICAM was decoded of course to feed the analogue TV sound transmitter. (The Beeb did it slightly differently, and it was re-clocked for Tx, (which is why the IBA and BBC flavours of DSiS were incompatible). Mr Technologist will have chapter and verse)
So the fault is odd, because by 1991 I'd have expected the sound to be lost as well. I know ITV dual operated the old analogue audio lines for a year or two after they went stereo in 1989. Possibly up until Jan 1993 when the contracts with BT expired ? Perhaps what we hear was coming up an analogue line still.
[1] Although the path for a networked programme would have been DSiS from the originating company. The audio decoded to analogue at you local ITV company (or taken to AES/EBU digiatl audio) for manipulation within pres etc, then re encoded into DSiS to travel to the local transmitter(s)
However, as TV-am by-passed the ITV companies, it would have been DSiS all the way, uninteruppted
That TV-am fault had me thinking, would the ITV blue caption, we see early on, have been generated at Camden Lock, where TV-am was, or at the local transmitter?
Robertclark125 post_id=57171 time= user_id=1163 Wrote:That TV-am fault had me thinking, would the ITV blue caption, we see early on, have been generated at Camden Lock, where TV-am was, or at the local transmitter?
The blue captions were at transmitter level, so if something happened at Central and (for argument's sake) Sutton Coldfield lost the feed from Central, that would generate the blue screen (and presumably same for all the relays that SC fed). But as I alluded to above, they usually said "Independent Television", whereas that one says ITV.
TV-am was a national service so didn't go through the ITV companies anyway, bypassing them en-route to the transmitters. So I think it may have been possible to be a localised issue. I was going to suggest the 6am handover had gone astray but you can work out from the video timings and the TV-am clock that the handover happens at 6am but Mark Longhurst sounds like he's starting his introductory spiel half a minute after the handover, and at that point the blue caption appears.
They don't seem aware of the problem on the off-air output anyway as there's no mention of it. So I can only presume it was both a local and a national issue?. If the whole lot had gone off at Camden Lock it could have been 1987 all over again which was a traipse up the road to Thames to get on air with something, anything.
Neil Jones post_id=57176 time= user_id=961 Wrote:The blue captions were at transmitter level, so if something happened at Central and (for argument's sake) Sutton Coldfield lost the feed from Central, that would generate the blue screen (and presumably same for all the relays that SC fed). But as I alluded to above, they usually said "Independent Television", whereas that one says ITV.
Yes the caption was generated at whichever transmitter this was recorded from after a certain period of loss of input. Of course it doesn't mean that it only happened from this transmitter, it could have been multiple, but each would generate its own caption from its own local generator.
Quote:
TV-am was a national service so didn't go through the ITV companies anyway, bypassing them en-route to the transmitters. So I think it may have been possible to be a localised issue. I was going to suggest the 6am handover had gone astray but you can work out from the video timings and the TV-am clock that the handover happens at 6am but Mark Longhurst sounds like he's starting his introductory spiel half a minute after the handover, and at that point the blue caption appears.
The caption and audio only appears at theat point because it's been x number of seconds since loss of video, once the transmitter has some valid video going into it the receiver can decide the audio too.
It probably was localised, but whether it was just this TX or the whole of the Midlands, or further afield who knows,
Quote:They don't seem aware of the problem on the off-air output anyway as there's no mention of it. So I can only presume it was both a local and a national issue?.
Even if it was a national issue - if it had been a circuit fault out of London they'd have probably not have mantjoned it that soon anyway. It would take a while to find out the extent of an outage and let TVam know. Even if they saw it on their off air in Camden they couldn't assume it was a national fault.
I wonder what sort of checks went on before it went to air, it was routed straight to the transmitters and was done automatically so would anyone at BT be checking the output was good and getting everywhere it needed to? Unlikely.
Camden could have had a confidence return from the BT Tower though
Inspector Sands post_id=57346 time= user_id=1003 Wrote:Neil Jones post_id=57176 time= user_id=961 Wrote:The blue captions were at transmitter level, so if something happened at Central and (for argument's sake) Sutton Coldfield lost the feed from Central, that would generate the blue screen (and presumably same for all the relays that SC fed). But as I alluded to above, they usually said "Independent Television", whereas that one says ITV.
Yes the caption was generated at whichever transmitter this was recorded from after a certain period of loss of input. Of course it doesn't mean that it only happened from this transmitter, it could have been multiple, but each would generate its own caption from its own local generator.
Quote:
TV-am was a national service so didn't go through the ITV companies anyway, bypassing them en-route to the transmitters. So I think it may have been possible to be a localised issue. I was going to suggest the 6am handover had gone astray but you can work out from the video timings and the TV-am clock that the handover happens at 6am but Mark Longhurst sounds like he's starting his introductory spiel half a minute after the handover, and at that point the blue caption appears.
The caption and audio only appears at theat point because it's been x number of seconds since loss of video, once the transmitter has some valid video going into it the receiver can decide the audio too.
It probably was localised, but whether it was just this TX or the whole of the Midlands, or further afield who knows,
Quote:They don't seem aware of the problem on the off-air output anyway as there's no mention of it. So I can only presume it was both a local and a national issue?.
Even if it was a national issue - if it had been a circuit fault out of London they'd have probably not have mantjoned it that soon anyway. It would take a while to find out the extent of an outage and let TVam know. Even if they saw it on their off air in Camden they couldn't assume it was a national fault.
I wonder what sort of checks went on before it went to air, it was routed straight to the transmitters and was done automatically so would anyone at BT be checking the output was good and getting everywhere it needed to? Unlikely.
Camden could have had a confidence return from the BT Tower though
This was during the dying era of the IBA. If it had happened in the 80s, then the regional RoC would have noticed, and been onto BT and/or TV-am. In fact maybe they were in this case, which is why the problem only lasted a couple of minutes.
The Croydon RoC was still operational in 1991, they phoned me up regarding a long running saga with C4 NICAM from Hannington
Well, here's two technical breakdowns I remember seeing. Can't remember if I've said these in this thread before however.
After a break during a Starsky and Hutch episode on Forces TV in early January 2019, a black screen appeared. It appeared for around a minute before a "Service Temporarily Available" slide came on. Problem got fixed shortly however.
There was this 30s film on Talking Pictures TV (forget the name), and when it ended, there was a few seconds of blank film left over, followed by a technical difficulty message telling viewers to "stay seated in the cinema" and that regular programming will resume as soon as possible, this happened around August/September 2019. Kind of like that Star Trek BBC technical difficulty back in the 80s.
TIGHazard post_id=57374 time= user_id=904 Wrote:Although not a full breakdown, Storm Barra causing a little bit of problem during Look North (NE&C) tonight... during a DTL interview about Storm Arwen
https://www.youtube.com/watch?v=zhhUmjJj4YY
Looks to me like yet another news editor learning the hard way that satellite dishes on vans don't work very well in high winds
Markymark post_id=57350 time= user_id=1078 Wrote:This was during the dying era of the IBA. If it had happened in the 80s, then the regional RoC would have noticed, and been onto BT and/or TV-am. In fact maybe they were in this case, which is why the problem only lasted a couple of minutes.
Yes, even post-IBA they'd have received some alarm that the feed had been lost, of course Arqiva's control room will still today. I suppose the difference then was that NTL weren't the broadcaster like the IBA was, so as long as their equipment was working it wasn't their issue. That doesn't mean they'd not have escalated it though
Inspector Sands post_id=57463 time= user_id=1003 Wrote:Markymark post_id=57350 time= user_id=1078 Wrote:This was during the dying era of the IBA. If it had happened in the 80s, then the regional RoC would have noticed, and been onto BT and/or TV-am. In fact maybe they were in this case, which is why the problem only lasted a couple of minutes.
Yes, even post-IBA they'd have received some alarm that the feed had been lost, of course Arqiva's control room will still today. I suppose the difference then was that NTL weren't the broadcaster like the IBA was, so as long as their equipment was working it wasn't their issue. That doesn't mean they'd not have escalated it though
Indeed. In fact I've got a feeling the phone call I received from the Croydon RoC was with an NTL rather than an IBA hat. I can’t remember at what exact point the ITV companies changed from being franchise holding programme contractors, to licence holding broadcasters, but that would have the point where transmitter faults became the direct concern of the companies. I've got a feeling it was in advance of Jan 1 1993?