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uk.tech.digital-tv (Digital TV - General) (uk.tech.digital-tv) Discussion of all matters technical in origin related to the reception of digital television transmissions, be they via satellite, terrestrial or cable. Advertising is forbidden, with no exceptions.

Inconsistent implementation of DVB T1 standard?



 
 
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  #11  
Old August 21st 13, 11:16 AM posted to uk.tech.digital-tv
Mark Carver
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Posts: 7,594
Default Inconsistent implementation of DVB T1 standard?

Bill Wright wrote:
I've been building a head end that has three DVB muxes, each carrying
four services. I tested it on a variety of TV sets and set top boxes.


Comments?


Nothing directly about this, but a related thing.

As mentioned a few weeks ago, my MIL was lined up to move into
a retirement flat, and McCarthy and Stone had banged on about a super
dooper system where the entrance CCTV camera pops up on the TV set on
the flat.

Well, yesterday she moved in. What it turns out to be is a 7th mux on
UHF E21 (in addition to the regular six local area muxes between E39-47)

She has two Sony tellies, a 2007 20 inch model, and a two year old
DVB-T2 model. I ran a manual scan, pointing them both at E21. Both
behaved the same way, a single channel was found called 'ENTRANCE DOOR'
and neither TV gave it a default LCN (unlike they do for proper
broadcast channels),
Instead both sets asked me which LCN I'd like the channel on. (I
selected LCN 8)

I did have a play with an LG set in the 'common room', and found the
CCTV channel on LCN 400 on that. I suspect, that's where the LG placed
the channel when someone ran its auto scan.

I'll take a look next time I'm there, and see out of interest whether
the CCTV mux is QSPK or 16QAM (whatever, it's certainly not T2 :-) )
  #12  
Old August 21st 13, 12:13 PM posted to uk.tech.digital-tv
Johny B Good[_2_]
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Posts: 853
Default Inconsistent implementation of DVB T1 standard?

On Wed, 21 Aug 2013 11:16:21 +0100, Mark Carver
wrote:

Bill Wright wrote:
I've been building a head end that has three DVB muxes, each carrying
four services. I tested it on a variety of TV sets and set top boxes.


Comments?


Nothing directly about this, but a related thing.

As mentioned a few weeks ago, my MIL was lined up to move into
a retirement flat, and McCarthy and Stone had banged on about a super
dooper system where the entrance CCTV camera pops up on the TV set on
the flat.

Well, yesterday she moved in. What it turns out to be is a 7th mux on
UHF E21 (in addition to the regular six local area muxes between E39-47)

She has two Sony tellies, a 2007 20 inch model, and a two year old
DVB-T2 model. I ran a manual scan, pointing them both at E21. Both
behaved the same way, a single channel was found called 'ENTRANCE DOOR'
and neither TV gave it a default LCN (unlike they do for proper
broadcast channels),
Instead both sets asked me which LCN I'd like the channel on. (I
selected LCN 8)

I did have a play with an LG set in the 'common room', and found the
CCTV channel on LCN 400 on that. I suspect, that's where the LG placed
the channel when someone ran its auto scan.

I'll take a look next time I'm there, and see out of interest whether
the CCTV mux is QSPK or 16QAM (whatever, it's certainly not T2 :-) )


That would be the most logical method since there's a whole mux
available for the job. The last thing you need is unnecessary
processing along with the 1 or 2 second delay that we're otherwise
forced to accept with broadcast TV.

I presume there's an audio back channel to the door entry system to
allow the occupants to _interact_ with any callers so the minimum of
processing should reduce propogation delay to a more acceptable
minimum.
--
Regards, J B Good
  #13  
Old August 21st 13, 12:22 PM posted to uk.tech.digital-tv
Mark Carver
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Posts: 7,594
Default Inconsistent implementation of DVB T1 standard?

Johny B Good wrote:

That would be the most logical method since there's a whole mux
available for the job. The last thing you need is unnecessary
processing along with the 1 or 2 second delay that we're otherwise
forced to accept with broadcast TV.


Actually that's a good point, I must measure the delay (see below)

I presume there's an audio back channel to the door entry system to
allow the occupants to _interact_ with any callers so the minimum of
processing should reduce propogation delay to a more acceptable
minimum.


Yes, there's an intercom system to talk to the front door, the audio channel
on the CCTV TV channel is just silence,


--
Mark
Please replace invalid and invalid with gmx and net to reply.
  #14  
Old August 21st 13, 04:13 PM posted to uk.tech.digital-tv
Bill Wright[_2_]
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Posts: 9,381
Default Inconsistent implementation of DVB T1 standard?

Glyn Morgan wrote:

I haven't done any transport stream analysis for over 5 years, I am
getting older & rusty, things may have changed, so this is possibly a
long shot.


Thanks very much for that. I will, for one thing, pass it on to Mike Rae
at Taylors.

Bill
  #15  
Old August 21st 13, 06:02 PM posted to uk.tech.digital-tv
Glyn Morgan
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Posts: 46
Default Inconsistent implementation of DVB T1 standard?

"Bill Wright" wrote in message ...
Thanks very much for that. I will, for one thing, pass it on to Mike Rae at
Taylors.


As an after-thought I would be interested to know what settings the Taylor
multiplex allows you to define and what values you have used.

I would be particularly interested to know if it lets you define the
original-network-id, network id, transport-stream-id and service-ids.

For all the UK DTT DVB allocated a value of 9018 (0x233A) for the
original-network-id. It is possible that if you are using something else
some receivers may think they are not in the UK and then mess-up where they
are looking for the LCNs. The other values are probably less critical.

Glyn



  #16  
Old August 21st 13, 09:25 PM posted to uk.tech.digital-tv
Bill Wright[_2_]
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Posts: 9,381
Default Inconsistent implementation of DVB T1 standard?

Mark Carver wrote:

Yes, there's an intercom system to talk to the front door, the audio
channel
on the CCTV TV channel is just silence,


We usually put a local radio station on there.

Bill
  #17  
Old August 21st 13, 09:28 PM posted to uk.tech.digital-tv
Mark Carver
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Posts: 7,594
Default Inconsistent implementation of DVB T1 standard?

Bill Wright wrote:
Mark Carver wrote:

Yes, there's an intercom system to talk to the front door, the audio
channel
on the CCTV TV channel is just silence,


We usually put a local radio station on there.


Round here that would only serve to reduce the overall entertainment value of
the channel.

--
Mark
Please replace invalid and invalid with gmx and net to reply.
  #18  
Old August 21st 13, 09:54 PM posted to uk.tech.digital-tv
Bill Wright[_2_]
external usenet poster
 
Posts: 9,381
Default Inconsistent implementation of DVB T1 standard?

Mark Carver wrote:
Bill Wright wrote:
Mark Carver wrote:

Yes, there's an intercom system to talk to the front door, the audio
channel
on the CCTV TV channel is just silence,


We usually put a local radio station on there.


Round here that would only serve to reduce the overall entertainment
value of the channel.

The oldies round here love Radio Sheff, although they say the poor
choice of music spoils it.

Bill
  #19  
Old August 22nd 13, 11:25 PM posted to uk.tech.digital-tv
Paul Ratcliffe
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Posts: 2,473
Default Inconsistent implementation of DVB T1 standard?

On Wed, 21 Aug 2013 16:13:05 +0100, Bill Wright wrote:

Glyn Morgan wrote:

I haven't done any transport stream analysis for over 5 years, I am
getting older & rusty, things may have changed, so this is possibly a
long shot.


Thanks very much for that. I will, for one thing, pass it on to Mike Rae
at Taylors.


I couldn't even open the bloody PDFs on the site. They just crash Acrobat
Reader. I gave up and departed for sunnier climes.
  #20  
Old August 23rd 13, 03:34 AM posted to uk.tech.digital-tv
Bill Wright[_2_]
external usenet poster
 
Posts: 9,381
Default Inconsistent implementation of DVB T1 standard?

Paul Ratcliffe wrote:
On Wed, 21 Aug 2013 16:13:05 +0100, Bill Wright wrote:

Glyn Morgan wrote:

I haven't done any transport stream analysis for over 5 years, I am
getting older & rusty, things may have changed, so this is possibly a
long shot.

Thanks very much for that. I will, for one thing, pass it on to Mike Rae
at Taylors.


I couldn't even open the bloody PDFs on the site. They just crash Acrobat
Reader. I gave up and departed for sunnier climes.

It's odd because I open them most days.

Bill
 




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