BBC Licence Fee Channels on 27.5w

A question for those in the know really, why are the Beeb transmitting license fee channels on 27.5w, I think these have just appeared recently, its transmitting onto an African beam, so no real chance of Northern Europe getting it, is it for the African providers?

Correction its on the Northern beam so it may be possible to get it with perhaps a professional setup?

Noticed all these channels are in DVB-S2, does this mean all these channels are HD?

According to Lyngsat they've been there since at least April (when their record of it was last updated)

Looking at the beam that they're on, you'd definately be able to get it here with the right reciever (no idea if DVB-S ones are easy to find), but there's no chance of getting it in Africa: http://www.lyngsat-maps.com/maps/intel907_spot1.html
Five are also on the same beam of the satellite: http://www.lyngsat.com/intel907.html



There are no HD versions of those channels so no.

As for why they're there, I've no idea, maybe it's some sort of distribution thing, possibly to cable? The Five regional feeds on there use 'Powervu' as their encryption which is only for professional use: http://en.wikipedia.org/wiki/PowerVu

And anyone wondering if they can pick this up, not likely without professional receiver, the FEC is way to high for current generation consumer DVB-S2 tuners.

DVB-S2 does not equate to HD neither does MPEG-4/H.264.

BTW Powervu is used as consumer encryption to

I gave it a go, picked up Five's encrypted channels, but no go with the Beebs channels as the FEC is too high.

Worth a shot, honestly never bothered to check when I saw the FEC I shrugged it off and ignored them.

Hmm - at those symbol rates and FECs they are presumably for non-consumer reception. (DVB-S2 and H264 for SD are used for some consumer systems in other countries - but the SR and FECs are very high)

That suggests they are more aimed at "big dish" reception?

Doing a back of envelope calculation - which could be wrong - they also appear to be pretty high bitrate for H264 - so it suggests that they are high quality sources for later processing? Could they be sustaining feeds?

8PSK = 3 bits per symbol. 5/6 FEC knocks that down to 2.5 bits per symbol after error correction. Symbol rate is around 40Mss, delivering around 100Mbs on the transponder? Assume the radio is all 256kbps - then that takes out around 4.5Mbs. That leaves around 95Mbs for the TV - which with 10 services means around 9.5Mbs per TV stream. That's very high for MPEG2 - so probably pretty close to broadcast quality for H264.

*EDIT - there are 12 streams not 10 as the Freeview Interactive streams are there - so nearer 8Mbs per stream *

*EDIT 2 - there could be 13 if News Interactive is there and hidden ? (Taking each stream to nearer 7.5 Mbs) *

Or have I got my maths totally wrong here? I think I must have somehow - 100Mbs seems too much for a single transponder. ISTR that SuperHiVision at IBC used two transponders for 140Mbs H264 using S2?

All of the services listed (apart possibly from the R4 DAB stream?) would be carried on the post-Freeview HD Mux 1 (when Mux B is switched to HD DVB-T2). Though there aren't BBC Interactive video streams listed?

*EDIT : Lyngsat didn't mention BBC Interactive streams but Flysat does - and they are called 301 and 302. The streams are attributed to Arqiva. This does sound like some means of feeding transmitter sites to me - it carries all the streams that will be on Mux 1 post-DSO and post-HD Freeview - apart from regional variations in England... *

*EDIT : No News Interactive stream though... Maybe that is flagged such that it can't be seen in the same way as 301 and 302 as it is a mosaic? *

Could these be sustaining feeds for digital TX sites? As they include BBC Nations feeds they aren't likely to be sustaining feeds TO the national or regional centres? There would need to be local MPEG2 encoders though - so that would be expensive? The lack of regional feeds makes me think twice about them being sources for digital cable - as does them being in MPEG4.

The satellite isn't in a particularly sensible position for broadcasting to active UK Armed Forces is it?

*** The more I think about it - the more this is likely to be a sustaining feed for Freeview transmitter sites - even though it would require local re-encoding - as the presence of 301 and 302 screams Freeview, and presumably there will be dishes pointed at 27.5W to downlink the Five feeds for the analogue transmitters co-sited at many locations? May be completely wrong though ***

Yes, I'd have thought that the new digital TX feeds would be distributed multiplexed as before

As for cable, the regional versions would originate at the various head-ends, but they all carry BBC1 London because of Audio Description, I believe the ex-NTL customers get the national versions too so it's possible. Although the odd choice of radio stations might rule out that possibility (no Radio 4 LW for example)

Hmm - I wonder if they are making the digital system more robust in preparation for analogue switch off? So providing a backup in case of loss of fibre feeds? But I can't see them installing a bunch of H264 decoders and full statmux encoders at every TX site for this?

It does seem to be all the Mux 1 post-DSO services though - as Five is there. Could it be a temporary sustaining feed whilst there are multiple versions of Mux 1 flying around? (AIUI there are three - An 18Mbs pre-DSO version, a 24Mbs post-DSO but pre-Freeview HD one designed to co-exist with Mux B, and a 24Mbs standalone one that assumes Mux B is entirely HD)

There may be only a single redundant Mux 1 fibre distribution feed structure currently (and eventually that is all that will be needed again)?

If there are currently multiple Mux 1 configs - a single feed wouldn't work as a backup - so maybe they have to provide redundancy via an alternate route?

And can a mod edit the thread to correct the typo in "LicenCe" please?

(I know I'm a pedant - but the noun is licenCe, the verb is licenSe)

No - S2 doesn't equal HD.

You can transmit HD via DVB-S (as the BBC and ITV do), and you can transmit SD via DVB-S2 (as a number of new European platforms do)

Similarly H264 (aka MPEG4) doesn't equal HD either. You can transmit HD using MPEG2 (as they do in the US, Japan and Australia) and you can transmit SD using H264 (as they do on terrestrial in Ireland, New Zealand, Slovenia, and partially France and Sweden)

DVB-S2 is a more efficient modulation system, and thus delivers more data for a given transponder bandwith. However it isn't backwards compatible with DVB-S.

Because in Europe many digital TV platforms launched SD-only and pre-DVB-S2 and pre-MPEG2, there are many consumer digital satellite systems based on SD MPEG2 DVB-S. Because HD arrived quite late in Europe, there are many digital HD systems based on HD H264 DVB-S2. Hence for consumer applications S2 does often suggest HD, as does H264. If platform operators with a large SD MPEG2 DVB-S installed receiver base wanted to switch to S2 and H264 they'd have to replace all their existing receivers. The costs of doing this may outweigh the savings in spectrum costs.

The BBC and ITV currently broadcast their HD channels alongside SD channels on the same transponders - and so have to stay DVB-S for their HD channels currently. (If all the UK PSBs on Freesat shared transponders they could re-jig and have an S2 transponder for their HD stuff - and either improve their quality or reduce their costs a bit...)

However many broadcasters have switched from DVB-S to DVB-S2 (and in some cases from MPEG2 to H264) for their satellite uplinks (for news trucks and for outside broadcasts) even for SD as they have only a small number of receivers and transmitters to upgrade, and the savings in satellite space are significant even for SD contributions.

It does sound like you could be correct, I'd have thought that they'd just send the MUXed stream over satellite as a backup, but then if there are multiple versions (including different versions for the nations) it might be easier to send all the services seperately and MUX on site. They would need equipment at every site, but then if it's only a temporary arrangement then you're only talking a handful of sets of kit at the moment. If it's a permanent arrangement as a backup then 50 odd sets of Muxing equipment and sat receivers plus the transponder is probably a good investment (and arguably a better arrangement than RBS)

The transponder is missing BBC2 Scotland, Wales and NI though, if you're right presumably those and the english regions get lost in the case of the backup being used




Is that where Five's feeds are now?

Yep - you wouldn't be able to uplink all the pre-encoded and statmuxed variants I guess (though it might be close if you just needed 4 variants of a single config of 24Mbs Mux 1?)



I suspect so.


ISTR that half of them are. They have always used two satellites for redundancy haven't they? (They can cope with sun outtage and a catastrophic failure that way) And there is a fibre feed for Croydon ever since heavy rain took Five off-air in London...