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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.

BBC News CHannel 107



 
 
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  #11  
Old March 26th 18, 06:18 PM posted to uk.tech.digital-tv
NY
external usenet poster
 
Posts: 1,329
Default BBC News CHannel 107

"Andrew" wrote in message
news
A few houses on the Northern fringes of the sussex village where
I live seem to have aerials pointing along the line of stane
street. This is the Roman road to Londinium, so presumably CP,
because I cannot think of any transmitters in the 37 miles
between me and CP.

One of them now has one of those Tri-boom wideband jobs on
a wavy, wibbly wobbly pole in the garden. It has white
coax so presumably a diy job.

I didn't think we could get CP down here, but they are on high
ground, while I only have line of sight to Midhurst. Grrr.


What does
http://www.macfh.co.uk/JavaJive/Audi...lculator.shtml
predict for your postcode and the other house's, for reception from CP? What
does the Signal Profile map look like?

Ads
  #12  
Old March 26th 18, 07:08 PM posted to uk.tech.digital-tv
Woody[_5_]
external usenet poster
 
Posts: 1,865
Default BBC News CHannel 107


"NY" wrote in message
o.uk...
"Andrew" wrote in message
news
A few houses on the Northern fringes of the sussex village where
I live seem to have aerials pointing along the line of stane
street. This is the Roman road to Londinium, so presumably CP,
because I cannot think of any transmitters in the 37 miles
between me and CP.

One of them now has one of those Tri-boom wideband jobs on
a wavy, wibbly wobbly pole in the garden. It has white
coax so presumably a diy job.

I didn't think we could get CP down here, but they are on high
ground, while I only have line of sight to Midhurst. Grrr.


What does
http://www.macfh.co.uk/JavaJive/Audi...lculator.shtml
predict for your postcode and the other house's, for reception from
CP? What does the Signal Profile map look like?


IMO one of the best and most useful pages on the web!


--
Woody

harrogate3 at ntlworld dot com


  #13  
Old March 26th 18, 07:32 PM posted to uk.tech.digital-tv
Max Demian
external usenet poster
 
Posts: 3,970
Default BBC News CHannel 107

On 26/03/2018 12:40, Woody wrote:
"Pinnerite" wrote in message
news
This morning I tried to view HD channels 107 (BBC News) and 108 (Al
Jazeera)
Both were breaking up. This is from Crystal Palace.

Lots of complaint messages from others but I couldn't find an
explanation
anywhere.


Are you sure they were from CP and not somewhere else longer range?


After the March 21st retune I was (apparently) getting COM7 and COM8
from Hannington on UHF 32 and 34 respectively. That worked for a day or
two, and then I lost COM8 altogether, so I can't get BBC4 HD, but /can/
get BBC News HD and Channel 4+1 (and others).

Has anyone else experienced this? (I'm not too bothered, as I'm resigned
to having to get BBC4 on SD in the future.)

--
Max Demian
  #14  
Old March 26th 18, 10:38 PM posted to uk.tech.digital-tv
NY
external usenet poster
 
Posts: 1,329
Default BBC News CHannel 107

"Woody" wrote in message
news

"NY" wrote in message
What does
http://www.macfh.co.uk/JavaJive/Audi...lculator.shtml
predict for your postcode and the other house's, for reception from CP?
What does the Signal Profile map look like?


IMO one of the best and most useful pages on the web!


Agreed. It's interesting to look at what gets in the way of signals from
out-of-region transmitters, in terms of hills. Where I used to live in
Oxfordshire I ought to have been able to get a fairly strong signal (in
terms of no obstructions) from a transmitter other than Oxford (the
strongest) except it was in the wrong direction, which suggests that aerials
are pretty good at rejecting off-axis signals and/or decoders are good at
looking for the strongest version of a given mux and ignoring weaker ones
from other transmitters.




What I want to know is how the hell I once got spurious multiplexes near
Leyburn from Emley Moor (or one of its relays) when the reception predictor
says the only thing that my aerial should be able to see (from *any*
direction) is Bilsdale. And that was with a narrow-band aerial (whatever
group Bilsdale used in analogue days, before we had the aerial changed to
wideband) pointing at Bilsdale, so whatever was breaking through was a)
roughly on the axis of the aerial (due to its polar response); and b) within
the sweet-spot of a Bilsdale grouped aerial (which I think used to used the
lowest UHF channels).

Since we got a wideband aerial, and the downlead was fettled as well, to
remove a bit of crushed coax as the lead entered the wall socket, reception
has been dramatically better, so good knows what bizarre signals had been
getting into the TV either from the aerial itself or from a badly-screen
downlead.

  #15  
Old March 27th 18, 01:52 AM posted to uk.tech.digital-tv
Bill Wright[_3_]
external usenet poster
 
Posts: 2,448
Default BBC News CHannel 107

On 26/03/2018 23:38, NY wrote:

What I want to know is how the hell I once got spurious multiplexes near
Leyburn from Emley Moor (or one of its relays) when the reception
predictor says the only thing that my aerial should be able to see (from
*any* direction) is Bilsdale.


Emley does seem to penetrate further than predictions would indicate in
that area.

And that was with a narrow-band aerial
(whatever group Bilsdale used in analogue days, before we had the aerial
changed to wideband) pointing at Bilsdale, so whatever was breaking
through was a) roughly on the axis of the aerial (due to its polar
response);


The polar response of an aerial when receiving an out-of-band signal is
almost random.

and b) within the sweet-spot of a Bilsdale grouped aerial


'Sweet spot' has many meanings (some of them unsuitable for a family
newsgroup) but it doesn't mean 'the design bandwidth of an aerial'.
Some Americans do use it in an RF context, but not to mean that.

(which I think used to used the lowest UHF channels).


Yes.

Bill
  #16  
Old March 27th 18, 07:26 AM posted to uk.tech.digital-tv
charles[_2_]
external usenet poster
 
Posts: 699
Default BBC News CHannel 107

In article , NY
wrote:
"Woody" wrote in message
news

"NY" wrote in message
What does
http://www.macfh.co.uk/JavaJive/Audi...lculator.shtml
predict for your postcode and the other house's, for reception from
CP? What does the Signal Profile map look like?


IMO one of the best and most useful pages on the web!


Agreed. It's interesting to look at what gets in the way of signals from
out-of-region transmitters, in terms of hills. Where I used to live in
Oxfordshire I ought to have been able to get a fairly strong signal (in
terms of no obstructions) from a transmitter other than Oxford (the
strongest) except it was in the wrong direction, which suggests that
aerials are pretty good at rejecting off-axis signals and/or decoders
are good at looking for the strongest version of a given mux and
ignoring weaker ones from other transmitters.





What I want to know is how the hell I once got spurious multiplexes near
Leyburn from Emley Moor (or one of its relays) when the reception
predictor says the only thing that my aerial should be able to see (from
*any* direction) is Bilsdale. And that was with a narrow-band aerial
(whatever group Bilsdale used in analogue days, before we had the aerial
changed to wideband) pointing at Bilsdale, so whatever was breaking
through was a) roughly on the axis of the aerial (due to its polar
response); and b) within the sweet-spot of a Bilsdale grouped aerial
(which I think used to used the lowest UHF channels).


Aircraft! In Keilder, I once received signals from Sandale/Caldbeck
entirely due to high flying planes.

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle
  #17  
Old March 27th 18, 07:58 AM posted to uk.tech.digital-tv
Woody[_5_]
external usenet poster
 
Posts: 1,865
Default BBC News CHannel 107


"Bill Wright" wrote in message
news
On 26/03/2018 23:38, NY wrote:

What I want to know is how the hell I once got spurious multiplexes
near Leyburn from Emley Moor (or one of its relays) when the
reception predictor says the only thing that my aerial should be
able to see (from *any* direction) is Bilsdale.


Emley does seem to penetrate further than predictions would indicate
in that area.

And that was with a narrow-band aerial (whatever group Bilsdale
used in analogue days, before we had the aerial changed to
wideband) pointing at Bilsdale, so whatever was breaking through
was a) roughly on the axis of the aerial (due to its polar
response);


The polar response of an aerial when receiving an out-of-band signal
is almost random.

and b) within the sweet-spot of a Bilsdale grouped aerial


'Sweet spot' has many meanings (some of them unsuitable for a family
newsgroup) but it doesn't mean 'the design bandwidth of an aerial'.
Some Americans do use it in an RF context, but not to mean that.

(which I think used to used the lowest UHF channels).


Yes.



If an aerial is receiving a useable signal on a side lobe it suggests
that there is too much incoming from the directed source. This means
either too much aerial system gain (with or without a masthead amp) or
a very sensitive TV.

I have noticed that in the days of analogue a signal of around 250uV
or more was desirable: with a digital TV 50uV or less still works
perfectly suggesting that modern technology has achieved an effective
tuner sensitivity increase of the order of 20dB.

I have a TV that sits on a 0dB gain antenna system overall (pointed at
Emley 26 miles away) and then has two splitters en route and it is
still self-tuning Belmont which is pretty well sideways on. I got
around the problem by tuning with an 18dB attenuator in series and it
still gives a perfect signal (but no Belmont!)


--
Woody

harrogate3 at ntlworld dot com


  #18  
Old March 27th 18, 02:30 PM posted to uk.tech.digital-tv
Bill Wright[_3_]
external usenet poster
 
Posts: 2,448
Default BBC News CHannel 107

On 27/03/2018 08:58, Woody wrote:

If an aerial is receiving a useable signal on a side lobe it suggests
that there is too much incoming from the directed source. This means
either too much aerial system gain (with or without a masthead amp) or
a very sensitive TV.


What do you mean by 'directed source'?

I have noticed that in the days of analogue a signal of around 250uV
or more was desirable:

with a digital TV 50uV or less still works
perfectly suggesting that modern technology has achieved an effective
tuner sensitivity increase of the order of 20dB.


No it's because, all other things being equal, the signal/noise ratio
for DTT can be 20dB lower.

I have a TV that sits on a 0dB gain antenna system overall (pointed at
Emley 26 miles away) and then has two splitters en route and it is
still self-tuning Belmont which is pretty well sideways on. I got
around the problem by tuning with an 18dB attenuator in series and it
still gives a perfect signal (but no Belmont!)


It's certainly true that some TV sets will attempt to store very weak
signals; weaker than are really any use.

Bill
  #19  
Old March 27th 18, 03:46 PM posted to uk.tech.digital-tv
Chris Youlden[_6_]
external usenet poster
 
Posts: 9
Default BBC News CHannel 107

On 26/03/2018 17:40, charles wrote:
In article ,
Mark Carver wrote:

Oooh, I'm told back in the analogue days, CP was receivable in Selsey
and the Witterings ?


Charles will know perhaps ?


Before my time - Once Rowridge came on, there would have been appaling
adjacent channel interference, but pre-Rowridge it might have been possible.
In the 405 days - who knows. I could get Rowridge here in a strong CP area.
I put the aerial up because Southern had better films than LOndon.


It depended, I would think, on how much of CP's signal diffracted over
the South Downs, but UHF could do that. It wouldn't have been reliable,
though.
--

Chris
  #20  
Old March 27th 18, 03:58 PM posted to uk.tech.digital-tv
Mark Carver[_2_]
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Posts: 439
Default BBC News CHannel 107

On 27/03/2018 16:46, Chris Youlden wrote:
On 26/03/2018 17:40, charles wrote:


It depended, I would think, on how much of CP's signal diffracted over
the South Downs, but UHF could do that. It wouldn't have been reliable,
though.


I've heard other stories of Bilsdale being received in Blackpool, same
effect ?

--
Mark
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