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What's On, Transponder and channel support
Transponders & channels
Which are the satellites used for cable and freeview feeds?
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<blockquote data-quote="Adam792" data-source="post: 1081915" data-attributes="member: 330868"><p>It’s more the fact that that sort of thing would be very expensive to implement at each transmitter site. No doubt way more expensive than having this existing back-up on a little used satellite position that is presumably way cheaper than more in-demand capacity like UK Spot beam 28.2°E. That’s why I wouldn’t be surprised if when/if it gets switched off from 27.5°W it just won’t be replicated anywhere - with them just deciding that any downtime suffered at any small transmitters just has to be dealt with (as the commercial PSB SD channels have already decided!)</p><p></p><p>Basically, as it stands the BBC Satback feeds on 27.5°W are all encoded ready in the right formats and bitrates so that the digital data can be fed directly into the terrestrial transmitters when the back-up is required, without having to touch the actual video/audio/ancillary data itself (aside from decrypting it which doesn’t take much effort). The relay transmitters that use it are only equipped to modulate the digital data as a DVB-T/DVB-T2 signal on a UHF frequency, they don’t have the facility to actually re-encode any video or audio which would be required if they didn’t use a tailor-made feed. They just take in the pre-encoded digital multiplex data, and whether this comes in via a terrestrial signal from a parent transmitter (most of the time) or via the 27.5°W back-up, it’s already all in the right format ready for transmission. This keeps the equipment at these very small transmitters pretty cheap and basic (in the grand scheme of things)!</p><p></p><p>A lot of the more problematic relay transmitters that struggled with off-air reception of their parent transmitter (and thus would have relied on the BBC Satback feed more frequently) have gradually become fibre-fed for the BBC multiplexes over the last few years. Transmitters in mid Wales and rural Somerset. If that continues then that would likely be the point at which Satback gets switched off once it’s not worth it for the tiny fraction of transmitters that ever need it any more!</p></blockquote><p></p>
[QUOTE="Adam792, post: 1081915, member: 330868"] It’s more the fact that that sort of thing would be very expensive to implement at each transmitter site. No doubt way more expensive than having this existing back-up on a little used satellite position that is presumably way cheaper than more in-demand capacity like UK Spot beam 28.2°E. That’s why I wouldn’t be surprised if when/if it gets switched off from 27.5°W it just won’t be replicated anywhere - with them just deciding that any downtime suffered at any small transmitters just has to be dealt with (as the commercial PSB SD channels have already decided!) Basically, as it stands the BBC Satback feeds on 27.5°W are all encoded ready in the right formats and bitrates so that the digital data can be fed directly into the terrestrial transmitters when the back-up is required, without having to touch the actual video/audio/ancillary data itself (aside from decrypting it which doesn’t take much effort). The relay transmitters that use it are only equipped to modulate the digital data as a DVB-T/DVB-T2 signal on a UHF frequency, they don’t have the facility to actually re-encode any video or audio which would be required if they didn’t use a tailor-made feed. They just take in the pre-encoded digital multiplex data, and whether this comes in via a terrestrial signal from a parent transmitter (most of the time) or via the 27.5°W back-up, it’s already all in the right format ready for transmission. This keeps the equipment at these very small transmitters pretty cheap and basic (in the grand scheme of things)! A lot of the more problematic relay transmitters that struggled with off-air reception of their parent transmitter (and thus would have relied on the BBC Satback feed more frequently) have gradually become fibre-fed for the BBC multiplexes over the last few years. Transmitters in mid Wales and rural Somerset. If that continues then that would likely be the point at which Satback gets switched off once it’s not worth it for the tiny fraction of transmitters that ever need it any more! [/QUOTE]
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What's On, Transponder and channel support
Transponders & channels
Which are the satellites used for cable and freeview feeds?
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