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Markymark4,978 posts since 13 Dec 2004
Meridian (North) South Today

This included the scenario where BBC NI was putting out its own schedule at the time.

Then that makes even less sense!


Correct. I'm struggling to recall how this was explained. It doesn't seem logical.


I can only think he was referring to slave-locking Belfast's master SPG to NET 1.

Really the best solution is to treat the integrity of any outside source as 'not to be trusted', and render it it locally synchronous with a frame store synchroniser, keeping your own local pulse distribution independent and free running. (Standard practice since the early 80s). That's fine, and that's how for instance ITV companies used to operate before all the centralisation.

The problem is, is when the 'nation' needs to be by-passed, and effectively NET 1 is fed directly to the local transmitters, switching in and out of that will produce a glitch or stutter.
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MMcG198397 posts since 14 Dec 2014
UTV Newsline
Then that makes even less sense!


Correct. I'm struggling to recall how this was explained. It doesn't seem logical.


I can only think he was referring to slave-locking Belfast's master SPG to NET 1.

Really the best solution is to treat the integrity of any outside source as 'not to be trusted', and render it it locally synchronous with a frame store synchroniser, keeping your own local pulse distribution independent and free running. (Standard practice since the early 80s). That's fine, and that's how for instance ITV companies used to operate before all the centralisation.

The problem is, is when the 'nation' needs to be by-passed, and effectively NET 1 is fed directly to the local transmitters, switching in and out of that will produce a glitch or stutter.


Thanks for this Mark. Interestingly, a fellow enthusiast recently recalled an incident in 1976 where the network feed seemed to go down. BBC One NI screens went black before switching to BBC Scotland, who were playing out their globe due to loss of network pictures. Odd how NI tripped to Scotland.
Steve in Pudsey8,538 posts since 4 Jan 2003
Yorkshire Look North (Yorkshire)
Divis took its analogue RBS feed from one of the Scottish transmitters, possibly Black Hill. For that incident it sounds like Belfast pres wasn't staffed and they were just passing network through the building to the transmitters. When the incoming feed failed the Glasgow pres suite was online and was providing a source of pictures which Divis took.
Write that down in your copybook now.
TonyCurrie341 posts since 19 Sep 2003
STV Central Reporting Scotland
How that worked was - the transmitters were programmed to monitor syncs and audio. If both failed, the TX switched to RBS (Re-Broadcast Standby) feed which was an off-air reserve. In the case of Divis it was from a south coast relay of Sandale, which in turn was fed from Black Hill.
The views expressed on this forum are entirely my own.
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Markymark4,978 posts since 13 Dec 2004
Meridian (North) South Today
How that worked was - the transmitters were programmed to monitor syncs and audio. If both failed, the TX switched to RBS (Re-Broadcast Standby) feed which was an off-air reserve. In the case of Divis it was from a south coast relay of Sandale, which in turn was fed from Black Hill.


Cambret Hill I think (a fairly powerful relay), 16kW back in the analogue days, so easily received at Divis.
RBS was supposed to be inhibited (by a VBI ident) during regional or national opts, to avoid the 'wrong' programme suddenly appearing (though surely something is better than nothing ?), but I witnessed my local Tx jumping to RBS during opts too
Last edited by Markymark on 11 November 2017 5:00pm
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robertclark1251,049 posts since 13 Jan 2009
STV Central Reporting Scotland
I believe there are some Scottish islands which can only pick up BBC Northern Ireland, or certainly they did only pick it up in analogue days. I'm sure the problem would be, if they were to try and site a relay, so they could pick up BBC Scotland, they may interfere with BBC NI signals, affecting people in Northern Ireland.

Is that still the case nowadays in digital broadcasting on freeview, that these islands cannot pick up BBC Scotland?