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Signal strength vs terrain vs distance



 
 
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  #1  
Old March 2nd 04, 06:26 PM
Nick Dyer
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Default Signal strength vs terrain vs distance

Hello! I live on the east side of the New Forest, about 16 miles from
the Rowridge transmitter on the IOW. I currently have middling to bad TV
reception due to a number of factors including a crap loft aerial, long
downleads of cheap co-ax, equally cheap splitters/combiners and the only
amplification being a booster just before the TV. I can get patchy
digital reception on everything but the ch52 mux (ITV/CH4). I want to
improve both the analogue reception and be able to receive all the
digital channels.

So I need to replace the aerial with a wideband one anyway. I was
thinking Antiference TC18W (reckoning I'm in a medium signal area). I've
done some searching through the various online sources of information on
this and am confused about a couple of issues:

1) Various people recommend using CT100 type cable above bog-standard
co-ax and that seems to make sense. Are f-type connectors really worth
it though?

2) 16 miles doesn't seem like a huge distance from the transmitter. Is
the digital signal likely affected by the low-lying hills for a couple
of miles south of me?

3) Without being able to afford a proper signal meter, what's the best
way of aligning an aerial? Are the signal strength meters in a DVB box
any use? Is it better to use a combination of this and a regular
analogue TV?

4) How much is loft-mounting really losing me in terms of signal? Can I
compensate by using a high-gain aerial? is it likely that I'll need some
kind of mast-head amplifier or will that just make it worse?

Sorry for all the questions. I'm fully expecting an answer like "it all
depends really"...

Nick
  #2  
Old March 2nd 04, 07:53 PM
simtan
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Default

Nick Dyer wrote:
Hello! I live on the east side of the New Forest, about 16 miles from
the Rowridge transmitter on the IOW. I currently have middling to bad
TV reception due to a number of factors including a crap loft aerial,
long downleads of cheap co-ax, equally cheap splitters/combiners and
the only amplification being a booster just before the TV. I can get
patchy digital reception on everything but the ch52 mux (ITV/CH4). I
want to improve both the analogue reception and be able to receive
all the digital channels.


Hold fire, isn't the ITV/C4 mux being moved soon to be "in group" with the
rest of the channels?

Sim


  #3  
Old March 2nd 04, 08:12 PM
Ben
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Default

Nick Dyer wrote:
Hello! I live on the east side of the New Forest, about 16 miles from
the Rowridge transmitter on the IOW. I currently have middling to bad TV
reception due to a number of factors including a crap loft aerial, long
downleads of cheap co-ax, equally cheap splitters/combiners and the only
amplification being a booster just before the TV. I can get patchy
digital reception on everything but the ch52 mux (ITV/CH4). I want to
improve both the analogue reception and be able to receive all the
digital channels.


You've described the problem, so it sounds like you already know what to
do. Roof aerial, CT100, no splitters/combiners, no booster.
Signal to noise ratio is the important thing for digital, you should
have a single uninterupted run of good quality screened cable so noise
doesn't get in.

So I need to replace the aerial with a wideband one anyway. I was
thinking Antiference TC18W (reckoning I'm in a medium signal area). I've
done some searching through the various online sources of information on
this and am confused about a couple of issues:

1) Various people recommend using CT100 type cable above bog-standard
co-ax and that seems to make sense. Are f-type connectors really worth
it though?

2) 16 miles doesn't seem like a huge distance from the transmitter. Is
the digital signal likely affected by the low-lying hills for a couple
of miles south of me?

3) Without being able to afford a proper signal meter, what's the best
way of aligning an aerial? Are the signal strength meters in a DVB box
any use? Is it better to use a combination of this and a regular
analogue TV?


I've aligned my antenna using a map and compass (there's a website where
you put your postcode in and it tells you details about your local
transmitters, including compass bearing). If there are local
obstructions then the optimum direction may not be directly towards the
transmitter, but depending on the beamwidth of the antenna you may get
away with it. When I got a professional in to fit a better aerial higher
up, he ended up pointing it in exactly the same direction, so I guess it
worked in my case.

4) How much is loft-mounting really losing me in terms of signal? Can I
compensate by using a high-gain aerial? is it likely that I'll need some
kind of mast-head amplifier or will that just make it worse?


Lots
No
Don't have any experience of masthead amplifiers myself, but they seem
to work for some people and make it worse for others. Probably always
preferable to a booster just before the TV though. I think the answer is
see if you can manage without one first.

Sorry for all the questions. I'm fully expecting an answer like "it all
depends really"...

Nick


  #4  
Old March 2nd 04, 08:21 PM
John R Whale
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Default



I've aligned my antenna using a map and compass (there's a website where
you put your postcode in and it tells you details about your local
transmitters, including compass bearing). If there are local
obstructions then the optimum direction may not be directly towards the
transmitter, but depending on the beamwidth of the antenna you may get
away with it. When I got a professional in to fit a better aerial higher
up, he ended up pointing it in exactly the same direction, so I guess it
worked in my case.


Do you have a link for that website - i could do with that, Ta


  #5  
Old March 2nd 04, 09:04 PM
Nigel Kendrick
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Default

Hold fire, isn't the ITV/C4 mux being moved soon to be "in group" with the
rest of the channels?

Sim


Yup, end of March, allegedly (Digital Spy web site)

NK


  #6  
Old March 2nd 04, 09:05 PM
Ben
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Posts: n/a
Default

John R Whale wrote:
I've aligned my antenna using a map and compass (there's a website where
you put your postcode in and it tells you details about your local
transmitters, including compass bearing). If there are local
obstructions then the optimum direction may not be directly towards the
transmitter, but depending on the beamwidth of the antenna you may get
away with it. When I got a professional in to fit a better aerial higher
up, he ended up pointing it in exactly the same direction, so I guess it
worked in my case.



Do you have a link for that website - i could do with that, Ta



If you put your postcode into www.multimap.co.uk it will tell you your
OS grid reference (under Map Information down at the bottom).

The transmitter info page is at http://www.wolfbane.com/articles/tvr.htm
you want Reception Predictors (by Ordnance Survey grid reference)

  #7  
Old March 2nd 04, 09:10 PM
Nigel Kendrick
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Default

One good trick when aligning the aerial is to have a darn good look at all
the aerials on adjacent properties! Fortunately in my group of houses we're
all line-astern to the transmitter so I had an almost perfect 'gunsight' to
use when replacing my Group A with a wideband for Rowridge IOW.

NK


  #8  
Old March 3rd 04, 04:15 AM
Bill
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Default

One good trick when aligning the aerial is to have a darn good look at all
the aerials on adjacent properties! Fortunately in my group of houses we're
all line-astern to the transmitter so I had an almost perfect 'gunsight' to
use when replacing my Group A with a wideband for Rowridge IOW.


Beware though. This can be misleading. I know of places where 90% of the
aerials are in agreement but are off-beam. An example is to hospital end of
Wentworth Road in Doncaster. The road is in alignment with Emley Moor, and the
Tx is visible on a clear day, but most aerials point about 25deg off to the
left. The residents will tell you that the nearby gasometer causes ghosting,
but actually it doesn't if the aerial is pointing at the Tx.
The reason this happens of course is that there are still a lot of installers
who guess which way to point the aerial.
Yours in sorrow for the deplorable state of my trade.

Bill


http://www.wrightsaerials.tv/index.html
  #9  
Old March 3rd 04, 10:09 AM
gbnews
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Default

Bill wrote:
One good trick when aligning the aerial is to have a darn good look
at all the aerials on adjacent properties! Fortunately in my group
of houses we're all line-astern to the transmitter so I had an
almost perfect 'gunsight' to use when replacing my Group A with a
wideband for Rowridge IOW.


Beware though. This can be misleading. I know of places where 90% of
the aerials are in agreement but are off-beam. An example is to
hospital end of Wentworth Road in Doncaster. The road is in alignment
with Emley Moor, and the Tx is visible on a clear day, but most
aerials point about 25deg off to the left. The residents will tell
you that the nearby gasometer causes ghosting, but actually it
doesn't if the aerial is pointing at the Tx.
The reason this happens of course is that there are still a lot of
installers who guess which way to point the aerial.
Yours in sorrow for the deplorable state of my trade.

Bill


http://www.wrightsaerials.tv/index.html


Bill can you recommend a good installer for the Coventry area? I'm only two
miles away from Allesley Park yet i've got shocking reception using a roof
aerial.

TIA,

gbnews


  #10  
Old March 3rd 04, 10:29 PM
Bill
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Default

Bill can you recommend a good installer for the Coventry area? I'm only two
miles away from Allesley Park yet i've got shocking reception using a roof
aerial.


I was involved recently in a reception problem in south Coventry, but it never
progressed as far as investigating the local riggers.
Sorry. I know there is someone in that area doing good work because I've been
all over the area and I've seen some good quality aerials properly installed,
but I never found out who had done them. His 'trademark' was a TC18E on a 12ft
mast with a double chimney kit. I was going to knock on doors and find out who
he was but it didn't get that far.

Bill
http://www.wrightsaerials.tv/index.html
 




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