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noggin14,271 posts since 26 Jun 2001
Wait so one of the BBC studios transmitters was fed by an off air signal provided by a third party?


What third party?

The BBC uplink their own DSat services - not Sky - even though those services are available to Sky viewers on Sky boxes.

The Sky receiver (which can be purchased commercially, similarly to any other IRD) was simply receiving a consumer signal that had been uplinked by the BBC. It wasn't receiving a Sky uplinked-signal.

The BBC uplinked-services are compatible with both Sky boxes and Freesat boxes, and contain EPG data etc. compatible with both platforms. Even in the early days of DSat, when the BBC were FTV-encrypted, and on Sky's platform only, the BBC arranged their own uplink (usually using BBC equipment, though some services may have come from an Arqiva uplink?) with Sky encryption equipment on BBC premises.

(Of course it's also worth pointing out that all transmitters in the UK are operated by a 'third party' - Arqiva. Neither the BBC, nor ITV/C4 operate their own OTA DVB-T/T2 transmitters.)

(Also not sure what you mean by 'BBC studios transmitters'? The transmitters in question are the main BBC One transmitters used in the East of England. Studios here don't really have transmitters.)
noggin14,271 posts since 26 Jun 2001
Ahh, I took 'replaced the opt switch' literally. Yes makes more sense to be at the TX site.


Quote:
On the opt switching .. the slgnalling was once a frame with a 3 frame window / hysteresis ...
And was also used at Bluebell Hill / Tunbridge Wells ..


What did that signal? Surely Cambridge could just put themselves nice and cleanly into Look East using their mixer/router

Also with at least two regions using DSAT receivers for their TX feed how did network recall work, if indeed it still existed then. And aspect ratio switching, the DSAT version would have been different to the analogue - no 14:9


If you had wanted to I suspect you could have run the DSat receiver in 16:9 FHA output - which would have switched between 4:3 12F12 and 16:9 16F16 output and used SCART-pin 8 switching to drive an external ARC that switched between bypass (For 12F12) and 14L12 (for 16F16), and instead sacrificed 16L12 output for movies?
noggin14,271 posts since 26 Jun 2001
And aspect ratio switching, the DSAT version would have been different to the analogue - no 14:9


Presumably it was a 'pro' D-Sat receiver, (you wouldn't want to use a Sky box, if there had been a power glitch, the Sky barker on Ch 999 would have been broadcast, with hilarious consequences !)

Ericsson made pro receivers that could output 14:9 I think ?


There were 'solutions' that automatically re-tuned Sky boxes to a chosen channel after a power glitch... (I know a lot of broadcasters used Sky domestic receivers - some with the SDI mods - rather than the 'Pro' receivers - as there was a still a major cost difference)

However I suspect you are right in this case Smile
Markymark6,611 posts since 13 Dec 2004
Meridian (North) South Today
And aspect ratio switching, the DSAT version would have been different to the analogue - no 14:9


Presumably it was a 'pro' D-Sat receiver, (you wouldn't want to use a Sky box, if there had been a power glitch, the Sky barker on Ch 999 would have been broadcast, with hilarious consequences !)

Ericsson made pro receivers that could output 14:9 I think ?


There were 'solutions' that automatically re-tuned Sky boxes to a chosen channel after a power glitch... (I know a lot of broadcasters used Sky domestic receivers - some with the SDI mods - rather than the 'Pro' receivers - as there was a still a major cost difference)

However I suspect you are right in this case Smile


Indeed. It's one thing to have a box that's used 'off-line' to record football highlights etc, easy reached in the equipment room, but quite another to have one that's part of the Tx chain locked away in an unoccupied building in the middle of nowhere on a desolate hill top !
Inspector Sands13,494 posts since 25 Aug 2004

Even in the early days of DSat, when the BBC were FTV-encrypted, and on Sky's platform only, the BBC arranged their own uplink (usually using BBC equipment, though some services may have come from an Arqiva uplink?)

Not sure that's right. My understanding is that either they were initially done by a third party and then came in house, or they started in-house, went out and back in.

Quote:
(Of course it's also worth pointing out that all transmitters in the UK are operated by a 'third party' - Arqiva. Neither the BBC, nor ITV/C4 operate their own OTA DVB-T/T2 transmitters.)

If there was ever a TV Forum pub quiz then one question would be: The BBC does own one set of TV transmitters that are in use and transmitting to the public. Where?



(sorry its not in Yorkshire, otherwise we'd be back on topic)
Last edited by Inspector Sands on 12 May 2019 10:24am
Markymark6,611 posts since 13 Dec 2004
Meridian (North) South Today

Even in the early days of DSat, when the BBC were FTV-encrypted, and on Sky's platform only, the BBC arranged their own uplink (usually using BBC equipment, though some services may have come from an Arqiva uplink?)

Not sure that's right. My understanding is that either they were initially done by a third party and then came in house, or they started in-house, went out and back in.


I think Arqiva (or ntl back then) uplinked the BBC channels from Crawley Court ? Back then it was
only a couple of transponders, because there were no English regions at that time.

When they went unencrypted, moved to Astra 2D, and three more ? (tps) were added it moved to an uplink Siemens had built near the east tower at W12 ?

Quote:
(Of course it's also worth pointing out that all transmitters in the UK are operated by a 'third party' - Arqiva. Neither the BBC, nor ITV/C4 operate their own OTA DVB-T/T2 transmitters.)

If there was ever a TV Forum pub quiz then one question would be: The BBC does own one set of TV transmitters that are in use and transmitting to the public. Where?




Ha ! I wonder if they own the actual transmitters, or whether Arqiva still run them ? And what about the PSB 2 Tx, is there a rental payment from ITV/4/5 to the Beeb ! Cool
noggin14,271 posts since 26 Jun 2001

Even in the early days of DSat, when the BBC were FTV-encrypted, and on Sky's platform only, the BBC arranged their own uplink (usually using BBC equipment, though some services may have come from an Arqiva uplink?)

Not sure that's right. My understanding is that either they were initially done by a third party and then came in house, or they started in-house, went out and back in.


Yes - you're right. However the BBC did arrange their own uplink (via Arqiva - though weren't they still NTL at that point?) rather than Sky uplinking them? I have a feeling the coding and mux was BBC (which became Siemens), with the uplink only handled by Arqiva? (The BBC TV Centre uplink came on stream when the English regions requirement was added - and I think operated by Siemens?)
Technologist25 posts since 10 Oct 2018
London London
Most if the time Sandy Heath was fed by the Radio link from Norwich .
AT some time before the opt Cambridge would signal to feed the Norwich output (rather than The contribution microwave from FRV Luton Nhampton) to it .
Put that through the mixer and then signal to feed Sandy by the return circuit ...
and signal to feed the transmitter from Cambridge ....
all that switching was in the SIS domain and I think if there had been
a Tek synchroniser it did not work well !!! So the opt switch was asynchronous..
( and a relay in any case)
Then you could gracefully fade over from Norwich to local sources.

Thus having a permanent feed that never opted at Sandy was seen
to be a great improvement

As the analogue was being fed by a digital distribution
.. the Network recall was done as it is for all digital services in coding and mux ...
its sort of how buddying works after all.
And I'm fairly certain that a sky box did 14:9 despite it being WSS not AFD.
Rkolsen2,664 posts since 20 Jan 2014
BBC World
Wait so one of the BBC studios transmitters was fed by an off air signal provided by a third party?


What third party?

The BBC uplink their own DSat services - not Sky - even though those services are available to Sky viewers on Sky boxes.

The Sky receiver (which can be purchased commercially, similarly to any other IRD) was simply receiving a consumer signal that had been uplinked by the BBC. It wasn't receiving a Sky uplinked-signal.

The BBC uplinked-services are compatible with both Sky boxes and Freesat boxes, and contain EPG data etc. compatible with both platforms. Even in the early days of DSat, when the BBC were FTV-encrypted, and on Sky's platform only, the BBC arranged their own uplink (usually using BBC equipment, though some services may have come from an Arqiva uplink?) with Sky encryption equipment on BBC premises.

(Of course it's also worth pointing out that all transmitters in the UK are operated by a 'third party' - Arqiva. Neither the BBC, nor ITV/C4 operate their own OTA DVB-T/T2 transmitters.)

(Also not sure what you mean by 'BBC studios transmitters'? The transmitters in question are the main BBC One transmitters used in the East of England. Studios here don't really have transmitters.)

I was going by this post:
That's right ...the "network feed" was Norwich output via microwaves to Sandy Heath,
There was a microwave feed to Hills road which either took that or a feed from the ENG dish which could take Northampton etc .
There then was a different microwave which took the Cambridge output back to Sandy Heath ..
This carried a signal in Teletext to do the opt switch at the transmitter and to select if Norwich or ENG was fed to Hill road .
The Ceefax and datacast etc was bridged from the incoming feed from Norwich to the feed to the transmitter down stream from the opt switch actually all of this was in the SIS domain .

When the BBC moved to Cambridge Business Park Cowley road ..... there was a feed of pure (digital) network there ... so the opt switch was replaced by a Sky DSAT receiver and Ceefax etc bridged in down stream of that ( and a NICAM modulator added )
The picture quality improved very noticeably ..... and there was no hard switch /opt
Northampton and Luton feeds were video over Ip codecs, ENG went satellite ..
The BBC saved a fortune in the cost of microwave links and the near impossibility of moving them
And Siemens who architected this ( based on analogue tv in Channel Islands ) got little recognition ...
Also the change over was easy ... as DSAT (and DTT) was via Central code and mux , it was just buddyed over the change over weekend .... no need to move "analogue"

I was going by the opt switch being replaced by Sky DSAT receiver.
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