This fantastic picture (courtesy of SES) shows satellite Astra 1N during testing. As you may recall, we moved many of our services on satellite over to Astra 1N earlier this year. I thought I'd share it with you as I have some news to tell you about a forthcoming change to the transponder on Astra 1N that carries BBC One HD and BBC HD.

During the summer last year we made a significant change to our HD transponder, upgrading the transmission mode of the BBC's signal from "DVB-S" to "DVB-S2".

This change meant that we were able to make more efficient use of the valuable satellite capacity available on our HD transponder. It gave us the ability to broadcast at 1920 resolution and conduct 3D trials on satellite for Wimbledon, Strictly Come Dancing, Street Dance, the London 2012 Olympic Games and, most recently, Planet Dinosaur.

Over the last year, we have worked closely with our colleagues at Sky, Freesat and SES to investigate how we can continue to make the most efficient use of our satellite capacity in light of improving technology. As a result, we are now able to make a further modification to the DVB-S2 operating parameters which enables us to access additional capacity. This will support the forthcoming launch of BBC One HD for Scotland, Wales and Northern Ireland.

We will be making this change during the early hours of 27 September 2012 and will update our reception advice page which details all our satellite tuning details at that time.

The change will mean different things to different people:

  • If you watch TV using Freeview or Virgin Media, or can't currently view HD channels you will not be affected.
  • If you have Sky, you should not notice the change and shouldn't have to do anything on or after 27 September. If you do have an issue receiving the BBC HD channels from this date you can try unplugging your Sky set top box, waiting 30s and plugging it back in again. If that doesn't resolve your problem it's best to contact Sky on 08442 411 653.
  • If you have Freesat you may need to put your HD box or TV into standby for 30 seconds and then switch it back on again to continue to receive the two BBC HD channels; if the channels are still unavailable then carry out a 'Freesat channel retune'. During last year's changes we found that a small number of devices didn't store the information after a Freesat retune so if that happens try a 'first time installation' or 'full factory reset'. Full instructions can be found in the manual for your digital TV or box. Further help with retuning can be found at www.freesat.co.uk or by calling their customer support team on 08450 990 990.
  • If you have any other kind of satellite receiver that can currently receive the BBC HD channels then you should use the new parameters below to tune manually into the services. The current and new parameters for Astra 1N tp.50 are:
Parameter Current New
Frequency 10,847 MHz (vertical polarity) unchanged
Modulation DVB-S2, QPSK DVB-S2, 8PSK
Symbol Rate 23.0 MSymb/s unchanged
FEC 8/9 2/3

We have also contacted satellite and aerial installer trade associations - dthe CAI and the RDI - providing them with information with which to brief their members in case anyone experiencing a problem contacts an installer rather than their platform operator. We will also be putting information about this change on the satellite BBC Red Button page 998 a bit nearer the time because we know not everyone has access to the internet.

If you watch our HD services on satellite, I hope this change won't cause you any worry.

Alix Pryde is Director, BBC Distribution

Follow @AbouttheBBC on Twitter for all the latest updates.

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  • Comment number 17. Posted by Alix Pryde

    on 3 Oct 2012 16:16

    Tech parameters
    @neil201, @Rodders_EID, @Briantist: Our choice of mode was taken after considering both theoretical and practical reception from Astra 1N, ensuring that we provide robust coverage across the whole of the UK. Should there be more margin from future satellites then we would consider a change of mode to ensure we were making best use of the capacity available to this, although at the moment we’ve no plans to make such a change.


    Red screen
    @Martin In Yorkshire: I can see that you're not a fan of the infamous red screen on BBC One HD during the opts! So I thought you might appreciate some explanation. The decision to show that and not, say, the BBC News channel, is a very carefully considered one that has been discussed at the highest level. Our concern is to ensure that we protect viewing of our national and English regional news programmes. And without being able to afford to make all variants of BBC One available in HD, we use the red screen to encourage viewers to go back to the standard definition version of BBC One where they will be able to watch the news from their area. We are looking into ideas to improve the experience cost-effectively. But for now, I'm afraid the red screen stays ... although watch out for a temporary change in the next week or so... (You heard it here first!)

  • Comment number 16. Posted by Alix Pryde

    on 3 Oct 2012 16:10

    First of all, thank you for reading my blog and for the varied questions and lively debate.

    I've just posted a new blog about some further changes and I've used that as a good place to answer some of the questions you raised:
    http://www.bbc.co.uk/blogs/aboutthebbc/posts/Satellite-Shuffling-reducing-BBC-Red-Button-and-expanding-BBC-One-HD

    * How will you broadcast four versions of BBC One HD and maintain picture quality (quick answer - by splitting them across two transponders!)
    * What EPG numbers will the nations versions of BBC One HD be found at? (quick answer, where you currently find BBC One HD)
    * Why are you launching versions of BBC One for the nations and not for big(ger) English Regions? Or other BBC services? (that's not a quick answer)

    So please do have a read.

    In answer to your other questions…

    1920
    @D Bowskill, @brightondancer and @popeye13: at the heart of each of your questions is resolution (but see also the statmuxing answer on the new blog). I recognise that 1920 resolution is an important issue for many respondents to BBC blogs in this area. And I also recognise that some receivers in the market are less good at scaling 1440 pictures to 1920 than others are. 1920 is an ambition for us but one we have to set against the high costs of capacity. So it can come down to a choice between 1920 or an additional stream. We are in the process of looking at future capacity requirements for HD services and the technical development of encoders in the market. So there are a number of moving pieces. But while we work this through, we will stay for now with the 1920 resolution we moved to in May.

  • Comment number 15. Posted by pklong

    on 13 Sept 2012 14:12

    As others here have mentioned BBC2, BBC3 and BBC4 HD would have been a much better use of the bandwidth....

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  • Comment number 14. Posted by RODABOD

    on 11 Sept 2012 11:56

    Regarding the satellite parameters, the current versus the future parameters will provide a very similar downlink margin. We also don't know how some viewers' equipment will handle the 8PSK modulation which is more susceptible to phase-noise which can afflict some LNBs. Regarding the statistical multiplexing issue, if it indeed is one, the only solution I can think of is if delay units are used to stagger the content. This could potentially be quite expensive.

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  • Comment number 13. Posted by wednesday83

    on 8 Sept 2012 22:15

    What a waste. We do not need a BBC1HD channel for each country. just pathetic political correntness from the beeb. What we need is BBC 3 and maybe 4 HD.

    All this means from what i can see is lowered bit rates and sub standard picture quality, all for no reason what so ever.

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  • Comment number 12. Posted by neil201

    on 6 Sept 2012 22:04

    Briantist: these figures all depend on the chosen FEC. The BBC are going for 2/3 so quite high for what, as described in post 5, is a now high power EiRP transponder with over 15dB carrier to noise, much better than 2D ever was, let alone 2A or B.

    Personally I think they should raise the FEC to 3/4, certainly once 2F is here as the C/N should see a 3dB improvement over 1N - 57dBW versus current 54dBW EiRP (data from SES's site). Alix, out of interest, are there plans to lower the FEC at a later stage once 2F is in place?

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  • Comment number 11. Posted by Briantist

    on 6 Sept 2012 19:40

    Basically, it's

    DVB-S on "old" satellite - 33.8Mbit/s
    DVB-S2 on "old" satellite using QPSK - 46 Mbit/s (36% more)
    DVB-S on "new" satellite - 44.4Mbit/s
    DVB-S2 on "new" satellite using 8PSK - 58.8Mbit/s

    Compare DVB-S2/8PSK to DVB-S2/QPSK -> 28% more

    http://tech.ebu.ch/docs/techreview/trev_300-morello.pdf has a nice explanation

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  • Comment number 10. Posted by Briantist

    on 6 Sept 2012 17:55

    @Rodders_EID: See http://www.satellite-calculations.com/Satellite/bitrates.htm

    Basically, it's 12% more bits.

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  • Comment number 9. Posted by Rodders_EID

    on 6 Sept 2012 15:19

    Hi Alix

    Can you please add some additional technical info on this change: i.e. what is the current data capacity / payload at QPSK and what will the new one be under 8PSK?

    We're all interested in what data rates are being allocated for the 3 extra HD channels... and will it be 5 or 6 streams in total from the 27th?

    Best regards to all in Distribution who know me ;)

    Rod

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  • Comment number 8. Posted by xm11

    on 6 Sept 2012 09:22

    interresting to be signal after switch to dvbs2 from spain

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