Apparently there are some additional tests in Scotland during the last 15 mins of each test. Presumably to do with RBS under opt out conditions, but I dunno why NI and Wales aren't doing similar tests.
Apparently there are some additional tests in Scotland during the last 15 mins of each test. Presumably to do with RBS under opt out conditions, but I dunno why NI and Wales aren't doing similar tests.
According to uk.tech.broadcast it's because of the new setup in Glasgow. It's the first RBS test since the move to Pacific Quay and it doesn't have a big traditional CTA (Central Technical Area) any more, so this is an extra bit of testing controlled from London
All the main DTT transmitters are currently fed fibre, and have local data insertion on top of the network feeds, so that they carry the correct transmitter ID etc.
Rebroadcasting them without decoding could be an issue - and if we ever move to single frequency networks simple rebroadcasting / relaying becomes impossible AIUI. (The transmitters have to be in-sync - as per DAB which also uses SFNs - for them to work)
Apparently (it is mentioned in the thread over on uk.tech.broadcast) there could be an issue with rebroadcasting even when it's not an SFN. The transmitter that's in RBS mode would be rebroadcasting the transmitter id for another transmitter which could cause confusion in the recievers at home. They woul have to strip off the data and then re-encode it again as part of the RBS system at each site
All the main DTT transmitters are currently fed fibre, and have local data insertion on top of the network feeds, so that they carry the correct transmitter ID etc.
Rebroadcasting them without decoding could be an issue - and if we ever move to single frequency networks simple rebroadcasting / relaying becomes impossible AIUI. (The transmitters have to be in-sync - as per DAB which also uses SFNs - for them to work)
Apparently (it is mentioned in the thread over on uk.tech.broadcast) there could be an issue with rebroadcasting even when it's not an SFN. The transmitter that's in RBS mode would be rebroadcasting the transmitter id for another transmitter which could cause confusion in the recievers at home. They woul have to strip off the data and then re-encode it again as part of the RBS system at each site
Yep - that was why I mentioned local data insertion at the transmitter...
BTW - if you ring Glasgow CTA, which is operated by Siemens, the guy (or gal) answers the phone "Hello, Glasgow CTA" - as you would expect. Except they are in TV Centre in London...
Apparently there are some additional tests in Scotland during the last 15 mins of each test. Presumably to do with RBS under opt out conditions, but I dunno why NI and Wales aren't doing similar tests.
This has been the case in the past anyway - though I believe that with last year's tests, Glasgow didn't have any test patterns available that didn't display a phone number, so switched out the incoming colour bars from Dundee.
This gets picked up by Divis, so it was seen in Northern Ireland too.
I've heard that during last year's tests, CCA had their usual contacts at all the main transmitter sites, making measurements on various bits of Tektronix kit - but also had an eye on the screengrabs being posted on TV Forum...
According to the uk.tech.broadcast group, the annual BBC RBS tests will take place on Wednesday 9th January, from 02:30-03:30 on BBC TWO and 04:30-05:30 on BBC ONE.
There's also some interesting discussion there about what will happen regarding the RBS tests as the UK starts the digital switch over.
Thank you very much for telling me that, I'll set my DVD recorder to record from both channels on the said date at the said times.
Does this mean they test the switching facility between London and Birmingham?
No, basically they turn of the feeds to all the transmitters except Crystal Palace, which triggers the RBS, a system which picks up an off air broadcast from a nearby mast so that it can continue broadcasting as normal.
Does this mean they test the switching facility between London and Birmingham?
No, basically they turn of the feeds to all the transmitters except Crystal Palace, which triggers the RBS, a system which picks up an off air broadcast from a nearby mast so that it can continue broadcasting as normal.
Yep, it's a worst case scenario, if it all works correctly every transmitter will be relaying the output of Crystal Palace, which means that by the time it gets to the extremes of the UK the picture will be very ropey indeed!
It's not designed to be run in this way with the whole network on RBS (unlike radio - witness the aircon failure incident this summer) - it's there for if one transmitter's feed drops. But it's easier to test the whole lot in one go by forcing the whole network onto RBS
Thank you very much for telling me that, I'll set my DVD recorder to record from both channels on the said date at the said times.
You might have a problem there. Set a VCR up too, as some DVD recorders stop when there is a signal drop out, which will happen at the start of the test and at the end.
IIRC the backup for the Selkirk BBC analogue services, if the Dunslair Heights link fails, was changed from an off-air feed of Black Hill to satellite a year or two ago. I don't know if it has ever been necessary to use that system.