BBC High Definition Multiplex on air now!

[Deleted User] · 28/02/06 - 19:15

I've been told some areas of London [Crystal Palace?] have a new BBC multiplex on channel 31. I think it's for the BBC's engineers to test the new high definition broadcasts that should be available for the Olympics [if not before].

Only BBC engineers with special boxes are supposed to be able to decode the streams but I'm sure we could do it with a DVB-T card and the right software, I have been able to decode French HD broadcast in this way.

I doubt they would bother to encrypt the test transmissions and there are lots of H.263 / 4 software decoders, even if they are using the BBC's own HD encoder [called DIRAC] it is open source and available here:

http://dirac.sourceforge.net/

http://www.bbc.co.uk/rd/projects/dirac/documentation/faq.htm

Can someone within range use their DVB-T card with TSReader or DVBStreamExplorer to dump a 50Mb sample of the transport stream and upload it for us?

Cheers,
Nick

mad_dude · 28/02/06 - 19:22

Getting a signal on channel 31 now maybe it is

reported in the signal strength meter

[Deleted User] · 28/02/06 - 19:24

If only I had TSReader (Not reader Lite)....

[Deleted User] · 28/02/06 - 19:30

What DVB-T card do you have? DVB Stream Explorer can dump the full transport stream from most devices [and you can then load that into TSReader lite using the file loop source].

Colin_London · 28/02/06 - 19:41

I can certainly see a signal on Channel 31 with 100% quality, but cannot get my Humax to recognise any streams.

Which, as it's not a HDTV box, I guess is correct

[Deleted User] · 28/02/06 - 20:28

There is definately a signal being sent on frequency channel 31, because I just went to retune my Sony IDTV and it sensed something on channel 31 but did not recognise what it was so it just stayed on that frequency.

F_F

[Deleted User] · 28/02/06 - 20:55

Goodmans GDB3 finds a signal too.

Just wish I had a DVB-T card...

Richard_T · 28/02/06 - 20:57

is it in mpeg4 or mpeg2? if its in mpeg 2 i think a toppy can record ( but not play it) and possibly the humax may be able to record it as well, although to veiw it i think it needs to be transfered to a P.C

[Deleted User] · 28/02/06 - 21:02

I can get a signal as well 75%, it is 8k where as the rest are 2k 64 QAM mux, but no channels available to my hauppauge winnova-t.
Link to a screen shot of the details.

[Deleted User] · 28/02/06 - 21:05

If you have a still camera that can take video - it may be MPEG4 and you may be able to display MPEG4 with the software for it loaded on your PC (This applies to my still camera - which has ACDsee software).

Somewhere on one of our PCs I have some MPEG2 (??) 1080i HD - which will display with one of the DVD player software loads I have - I cannot remember which (it may not be an MPEG2 file but try any players you have). It is on my work Laptop which is ... at work !

[Deleted User] · 28/02/06 - 21:07

James can you try and do an SI scan with DVBStreamExplorer?

www.dvbstreamexplorer.dk

Let meknow if you need any help.

Cheers,
Nick

Victor · 28/02/06 - 21:43

I'm also picking it up on my Twinhan card, signal strength 50%, quality 80%. Unfortunately, the utility I use to capture transport streams won't capture this, and DVBStreamExplorer won't work as I'm still using '98SE.

Vic

chrisy · 28/02/06 - 21:45

Colin_London wrote:

I can certainly see a signal on Channel 31 with 100% quality, but cannot get my Humax to recognise any streams.

There may not be any streams - it is likely that this isn't fully set up yet and has no SI data.

You should at least get an LCN (if your box recognises and assigns fake LCNs to channels without them) for each channel even if the data in the stream isn't recognisable.

Some people could see the DVB-H channels in Oxford on their DTT boxes, and the broadcast parameters there would have been even more different.

Chris

[Deleted User] · 28/02/06 - 21:46

I still have some sample streams from the DVB-H trials, unfortunately there are no public programs that could deal with the MPE and IPsec systems they were using.

Victor, TSReader Lite supports most Twinhan cards, you won't be able to do a full TS dump but can you post a screen-shot of it tuned to that multiplex?

http://www.coolstf.com/tsreader/

Thanks

Victor · 28/02/06 - 21:53

This any good?

http://img16.imagevenue.com/img.php?loc=loc261&image=63587_tsreader2.jpg

Vic

[Deleted User] · 28/02/06 - 21:57

Is 8K 1/4 64QAM 1/2 likely to be HD ? - I would guess is more likely DVB-H or is there another transmitter anywhere also broadcasting on 31. Not here at Rowridge as 31 is analogue - but what about something nearer London. For SFN tests the transport can be rubbish - it just has to be measurable and identical from two transmitters...

The parameters seem wrong for something that requires high bandwidth.

The BBC satellite 1080i transmission I have is 23Mb/s and it would not fit!

I am assuming 1/4 GI and 1/2 FEC (CR=CorrectionRatio=FEC?) in the above figures - does someone know the mode used in the Oxford DVB-H tests ? !/4 GI is about the highest you can go and is only sensible for SFNs or (maybe) mobiles.

Isn't there supposed to be an 'adverts in taxis' DVB-H system starting 'soon' in London ????

Also channel 31 does not fit into the 'unavailable for DTT' that the HD test frequency is supposed to be on.

Nick{D}vB - do you know the mode used for DVB-H tests - sorry - trials ?

[Deleted User] · 28/02/06 - 22:00

Thanks Victor 8)

It looks like there is nothing there yet. 8(

But keep an eye on it for us!

Cheers,
Nick

[Deleted User] · 28/02/06 - 22:17

SimonBlackham wrote:

Is 8K 1/4 64QAM 1/2 likely to be HD ? - I would guess is more likely DVB-H or is there another transmitter anywhere also broadcasting on 31. Not here at Rowridge as 31 is analogue - but what about something nearer London. For SFN tests the transport can be rubbish - it just has to be measurable and identical from two transmitters...

For me here in the centre of town it used to be a fuzzy analogue picture presumably from Sandy Heath.

My Win/TV card now locks onto the signal (although the signal strength seems to be jumping all over the place) however DVBStreamExplorer when scanning has a hissy fit on channel 31 complaining about no PAT/NIT data.

I would imagine if the ERP is low the higher settings would be necessary to overcome the incoming interference.

The parameters seem wrong for something that requires high bandwidth.

The BBC satellite 1080i transmission I have is 23Mb/s and it would not fit!

Except that is MPEG2, it is unlikely that this would be used terrestrially. Even terrestrial MPEG2 HD in the US can be around 12-14mbit/s, their entier 6MHz channel only yields 19mbit/s in the first place.

[Deleted User] · 28/02/06 - 22:19

SimonBlackham wrote:

Also channel 31 does not fit into the 'unavailable for DTT' that the HD test frequency is supposed to be on.

I think what they meant by unavailable for DTT was that it couldn't be used as part of a national DTT network (because there aren't enough freqs left to get MUX 7 pre-switchover. Of course the HD trial will be DTT what ever.)

[Deleted User] · 28/02/06 - 22:31

mjk79 wrote:

I would imagine if the ERP is low the higher settings would be necessary to overcome the incoming interference..

But GI 1/4 ??? - the GI is only large for big path differences in multipath reception - and a large GI weakens the signal - so would not be used unless required ? (I asked about the mode for DVB-H because they may have used big GIs too)

The HD tests satellite tests would be available for transmission without involving the rest of the system - although REDBEE seems to be saying that they are ready.

I do hope they are HD (or even SFN) tests - but I fear they are not.

Did anyone notice the DTG report about the contractor for conversion wanting a decision on HD - as it would cost an extra £70m if it is left till later... http://www.dtg.org.uk/news/news.php?class=countries&subclass=193&id=1502

[Deleted User] · 28/02/06 - 22:47

@SimonBlackham

DVB-H trial info:

http://www.dvb-h-online.com/Services/services-oxford.htm

http://www.dvb-h-online.com/Services/services-cambridge.htm

http://www.dvb-h-online.com/technology.htm

I can't remember the RF spec as I didn't dump the streams myself, I still have the samples somewhere if you want a look.

I also have test samples from the HD DVB-T service operating in Paris, again I don't have the RF details but I can ask the guy who dumped them for me.

Cheers,
Nick

[Deleted User] · 28/02/06 - 22:52

SimonBlackham wrote:

But GI 1/4 ??? - the GI is only large for big path differences in multipath reception

Who knows, whatever it is it's still a test and these parameters can be quite easily changed and perhaps will be one some data starts appearing on it.

You'd also expect that a low powered mobile DVB-H test wouldn't be using 64QAM.

[Deleted User] · 28/02/06 - 23:07

mjk79 wrote:

Who knows, whatever it is it's still a test and these parameters can be quite easily changed and perhaps will be one some data starts appearing on it.

You'd also expect that a low powered mobile DVB-H test wouldn't be using 64QAM.

Yes I think thats right - the figures look more like SFN to me - but as you say - they can change - in fact tests usually do try a range of parameters - perhaps the parameters will change tomorrow ? - and the next day? ...

Does anyone remember what the proposed 8K spec is exactly ? - I don't think either 1/4 GI or 1/2 FEC is anywhere near (although it is 8K 64QAM). If it were SFN tests then the power would have to be high enough to interfere / augment another transmitter - and it sounds like the signal is too low for that.
Perhaps they are just soak testing a new transmitter amp ready for tests to start soon and the 1/4 GI is just a nice harsh test with the amp four clicks on one off ?

(PS... CR = CodeRate - but still = FEC - error in previous post.)

nvingo · 28/02/06 - 23:11

Maybe the carrier is present, and will be made available to engineers from both DVB-H and HD-DTT camps as and when they have something to test/trial on it ?

[Deleted User] · 28/02/06 - 23:24

I think its a case of watch this space !!!

Hopefully when ( or if ??) data does arrive - someone gets it - and the mode it was transmitted at.

[Deleted User] · 01/03/06 - 10:41

I hope there are people still watching - especially through the day - as engineers don't like working nights or weekends !!!

Perhaps what was seen yesterday was just out-of-hours idling ? - and any tests are done in short bursts during working hours ?

How about leaving the HDD recorder or VCR on the manual tuning page all day if you have a suitable STB (eg Setpal, Astratec or Matsui with the earlier software) - or record the PC screen from the video out (if you have it - and cannot record the whole day to disc)

With my gear - if there were a test channel here at Rowridge - I would record the Astratec manual tune page to the HDD recorder or 8 hour VCR tape.

Hey there!

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