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Oh dear..... High winds......



 
 
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  #31  
Old March 6th 19, 06:50 PM posted to uk.tech.digital-tv
Bill Wright[_3_]
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Posts: 3,532
Default Oh dear..... High winds......

On 06/03/2019 17:53, Chris Green wrote:
Bill Wright wrote:
This is why the aerial job is buggered. People get away with murder. As
many of you will know I am very concerned about global warming, and I
think the transmitters should be turned down 20dB to save electric.

To save electric what?


Electric electric.

Bill
  #32  
Old March 6th 19, 06:52 PM posted to uk.tech.digital-tv
Bill Wright[_3_]
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Posts: 3,532
Default Oh dear..... High winds......

On 06/03/2019 18:29, charles wrote:
In article ,
Chris Green wrote:
Bill Wright wrote:
This is why the aerial job is buggered. People get away with murder. As
many of you will know I am very concerned about global warming, and I
think the transmitters should be turned down 20dB to save electric.

To save electric what?


ity


Thanks for translating Charles. I didn't realise it was necessary.

Bill
  #33  
Old March 6th 19, 07:05 PM posted to uk.tech.digital-tv
charles[_2_]
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Posts: 905
Default Oh dear..... High winds......

In article , Bill Wright
wrote:
On 06/03/2019 18:29, charles wrote:
In article , Chris Green
wrote:
Bill Wright wrote:
This is why the aerial job is buggered. People get away with murder.
As many of you will know I am very concerned about global warming,
and I think the transmitters should be turned down 20dB to save
electric.

To save electric what?


ity


Thanks for translating Charles. I didn't realise it was necessary.


My pleasure, Bill

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle
  #34  
Old March 6th 19, 07:16 PM posted to uk.tech.digital-tv
NY
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Posts: 1,684
Default Oh dear..... High winds......

"Chris Green" wrote in message
...
Bill Wright wrote:
This is why the aerial job is buggered. People get away with murder. As
many of you will know I am very concerned about global warming, and I
think the transmitters should be turned down 20dB to save electric.


Are the digital transmitters run at the same power levels as the analogue
ones were? Or was the power turned down at all as each transmitter had its
DSO day?

I suppose every transmitter site now broadcasts up to 8 multiplexes (plus a
ninth much more local, directional one, in many cases) whereas in the days
of analogue there were only 3, rising to 4 with CH4 and then 5 with Five.

How much would coverage be reduced (especially in places that have marginal
reception at present) if all the muxes were 20 dB less powerful? I suppose
it might lead to a lot of work for people like you, Bill, installing larger,
higher-gain aerials and maybe masthead amplifiers. ;-)

  #35  
Old March 6th 19, 08:01 PM posted to uk.tech.digital-tv
Mark Carver
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Posts: 6,512
Default Oh dear..... High winds......

On 06/03/2019 19:16, NY wrote:
"Chris Green" wrote in message
...
Bill Wright wrote:
This is why the aerial job is buggered. People get away with murder. As
many of you will know I am very concerned about global warming, and I
think the transmitters should be turned down 20dB to save electric.


Are the digital transmitters run at the same power levels as the
analogue ones were? Or was the power turned down at all as each
transmitter had its DSO day?


It's not quite that simple. Analogue ERP was quoted as 'peak vision
sync' because we used negative modulation, the sync pulses (4.7 us in
every 64 us) represented this max value. Most of the time the ERP was a
lot less than that, and was picture content dependent. Test Card F
represented I think 50% APL (Average picture level) which is, the
average picture ! Syncs represented 300mV of the 1V P-P video, so you
might broadly say average ERP was about 40%ish of the quoted value.
It's also why with a really weak signal, the picture would lock, even
though you couldn't make out any actual detail in the noise !

DTT is different, it's several thousand carriers spread over the 8 MHz
'window' On an analyzer a DTT mux is just a 'lump of grass' with steep
sides. It was decided to set the average DTT power at -7dB of analogue
values. There are exceptions, but for instance Crystal P that was 1000kW
analogue, is 200 kW digital.

How much would coverage be reduced (especially in places that have
marginal reception at present) if all the muxes were 20 dB less
powerful?


That's easy, don't you remember pre-DSO DTT, that's more or less what
the power levels were !

--
Mark
Please replace invalid and invalid with gmx and net to reply.
  #36  
Old March 6th 19, 08:17 PM posted to uk.tech.digital-tv
James Heaton
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Posts: 170
Default Oh dear..... High winds......


"Bill Wright" wrote in message
...
On 06/03/2019 08:26, Mark Carver wrote:
I used to suffer break up in the summer on wet and windy days due to
my outdoor aerial 'looking' through a line of trees.

I had some roof work done a couple of years ago, that required the aerial
to be removed. A few weeks in advance, I rigged up a log-p
in the loft. Naturally lower than the roof top, but it did have the
advantage of looking under the tree canopy, and signal was (and is)
stable.
The muxes still flap around a fair bit looking on an analyser, but the
tellies are not visibly troubled.

The aerial is looking straight out of the gable end of the house, which
is tiled with oxide red wall tiles, so it really is asking for trouble
when it comes to attenuation, I think I measured an 8dB loss in
experiments but hey, it works and still delivers enough signal, so I've
not bothered to reinstate the roof top aerial (which has gained me
brownie points from Mrs C)


This is why the aerial job is buggered. People get away with murder. As
many of you will know I am very concerned about global warming, and I
think the transmitters should be turned down 20dB to save electric.


Absolute radio have done so on their MF transmitters.

Quite substantially in some cases.

They reckon they are the last MF national music station in Europe!

James


  #37  
Old March 6th 19, 10:08 PM posted to uk.tech.digital-tv
Mark Carver
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Posts: 6,512
Default Oh dear..... High winds......

On 06/03/2019 20:17, James Heaton wrote:

This is why the aerial job is buggered. People get away with murder.
As many of you will know I am very concerned about global warming, and
I think the transmitters should be turned down 20dB to save electric.


Absolute radio have done so on their MF transmitters.


Well, yes, but only 3 dB (Half power)

Quite substantially in some cases.


True, some of the little fill-ins have been reduced by infinity dB.

--
Mark
Please replace invalid and invalid with gmx and net to reply.
  #38  
Old March 7th 19, 08:34 AM posted to uk.tech.digital-tv
Mark Carver[_2_]
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Posts: 612
Default Oh dear..... High winds......

On 06/03/2019 18:29, charles wrote:
In article ,
Chris Green wrote:
Bill Wright wrote:
This is why the aerial job is buggered. People get away with murder. As
many of you will know I am very concerned about global warming, and I
think the transmitters should be turned down 20dB to save electric.

To save electric what?


ity


The Southern Electricity Board 'rebranded' themselves Southern Electric
in 1987 ish. I'd helpfully suffix 'ity' to their name on the payment
invoice when sending them my cheque, as part of my campaign to resist
marketing ********. (My 32 year campaign has fallen short of success so
far)


--
Mark
Please replace invalid and invalid with gmx and net to reply.
  #39  
Old March 7th 19, 10:51 AM posted to uk.tech.digital-tv
Bill Wright[_3_]
external usenet poster
 
Posts: 3,532
Default Oh dear..... High winds......

On 06/03/2019 20:01, Mark Carver wrote:

It's not quite that simple. Analogue ERP was quoted as 'peak vision
sync' because we used negative modulation, the sync pulses (4.7 us in
every 64 us) represented this max value. Most of the time the ERP was a
lot less than that, and was picture content dependent. Test Card F
represented I think 50% APL (Average picture level) which is, the
average picture ! Syncs represented 300mV of the 1V P-P video, so you
might broadly say average ERP was about 40%ish of the quoted value.
It's also why with a really weak signal, the picture would lock, even
though you couldn't make out any actual detail in the noise !


Historically lock could be the limiting factor, which might explain sync
pulse levels right through to the end of analogue.



DTT is different, it's several thousand carriers spread over the 8 MHz
'window' On an analyzer a DTT mux is just a 'lump of grass' with steep
sides. It was decided to set the average DTT power at -7dB of analogue
values. There are exceptions, but for instance Crystal P that was 1000kW
analogue, is 200 kW digital.

How much would coverage be reduced (especially in places that have
marginal reception at present) if all the muxes were 20 dB less powerful?


That's easy, don't you remember pre-DSO DTT, that's more or less what
the power levels were !


In the end the fact that we had years and years of low powered DTT
brought the country's 'estate' of rx aerials up to a much higher
standard than previously. The trade is still in the doldrums partly
because of this.

Bill

  #40  
Old March 7th 19, 10:53 AM posted to uk.tech.digital-tv
Bill Wright[_3_]
external usenet poster
 
Posts: 3,532
Default Oh dear..... High winds......

On 07/03/2019 08:34, Mark Carver wrote:
On 06/03/2019 18:29, charles wrote:
In article ,
*** Chris Green wrote:
Bill Wright wrote:
This is why the aerial job is buggered. People get away with murder. As
many of you will know I am very concerned about global warming, and I
think the transmitters should be turned down 20dB to save electric.

To save electric what?


ity


The Southern Electricity Board 'rebranded' themselves Southern Electric
in 1987 ish. I'd helpfully suffix 'ity' to their name on the payment
invoice when sending them my cheque, as part of my campaign to resist
marketing ********. (My 32 year campaign has fallen short of success so
far)


I tend to say 'electric' as an affectation because that's the common
parlance hereabouts. I like to pretend I'm a man of the people even
though I look down on the common herd just as if I'm a politician.

Bill
 




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