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Strange reception issues on Ch55 and 56 from Rowridge



 
 
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  #1  
Old October 6th 18, 04:32 PM posted to uk.tech.digital-tv
Jeff Layman[_2_]
external usenet poster
 
Posts: 796
Default Strange reception issues on Ch55 and 56 from Rowridge

I have just fitted a 36-element log-periodic
(https://www.amazon.co.uk/AERIAL-LOG-...=optima+aerial)
in place of a Group A 18-element yagi so that I can get Com7/8. I am
about 18 miles from Rowridge, apparently in a "good" reception area. The
aerial is in the loft, feeding an old Labgear 6-way distribution amp.

All the Group A channels come through at 10 signal strength and 10
signal quality (Panasonic TV). But Com 7/8 on Ch 55 and 56 were only
showing 7 strength and 3 -5 quality at best. Rarely the signal was lost
for a second or two with a black screen and "No signal" on the TV.

I have some old amps, and rather than fit a 26dB gain masthead amp
(which I thought might overload the Group A signals), I fitted a set-top
11dB amp as a temporary "masthead" amp. This immediately improved the
signal received via Ch56. Strength was up to 9, and quality was now 7.
But Ch55 was not as good. Signal strength was still 7 and quality at 3
or 4 with the odd lost signal.

That was all about 30 minutes ago. Now Ch55 and 56 are both showing 9
strength and 9 quality! Maybe it's reception conditions today, but what
is/was going on with Com 7/8 reception? Why the marked difference
between Ch55 and 56 using the "masthead" amp?

--

Jeff
  #2  
Old October 6th 18, 06:02 PM posted to uk.tech.digital-tv
Jeff Layman[_2_]
external usenet poster
 
Posts: 796
Default Strange reception issues on Ch55 and 56 from Rowridge

On 06/10/18 16:32, Jeff Layman wrote:
I have just fitted a 36-element log-periodic
(https://www.amazon.co.uk/AERIAL-LOG-...=optima+aerial)
in place of a Group A 18-element yagi so that I can get Com7/8. I am
about 18 miles from Rowridge, apparently in a "good" reception area. The
aerial is in the loft, feeding an old Labgear 6-way distribution amp.

All the Group A channels come through at 10 signal strength and 10
signal quality (Panasonic TV). But Com 7/8 on Ch 55 and 56 were only
showing 7 strength and 3 -5 quality at best. Rarely the signal was lost
for a second or two with a black screen and "No signal" on the TV.

I have some old amps, and rather than fit a 26dB gain masthead amp
(which I thought might overload the Group A signals), I fitted a set-top
11dB amp as a temporary "masthead" amp. This immediately improved the
signal received via Ch56. Strength was up to 9, and quality was now 7.
But Ch55 was not as good. Signal strength was still 7 and quality at 3
or 4 with the odd lost signal.

That was all about 30 minutes ago. Now Ch55 and 56 are both showing 9
strength and 9 quality! Maybe it's reception conditions today, but what
is/was going on with Com 7/8 reception? Why the marked difference
between Ch55 and 56 using the "masthead" amp?


Maybe it's a device issue. I just retuned my Panasonic PVR and on the
quality of Ch56 (about 2) is considerably lower than that of Ch55 (about 5)!

--

Jeff
  #3  
Old October 6th 18, 07:09 PM posted to uk.tech.digital-tv
Bill Wright[_3_]
external usenet poster
 
Posts: 2,949
Default Strange reception issues on Ch55 and 56 from Rowridge

On 06/10/2018 18:02, Jeff Layman wrote:

Maybe it's a device issue. I just retuned my Panasonic PVR and on the
quality of Ch56 (about 2) is considerably lower than that of Ch55 (about
5)!


The higher the channel number the more the signal degradation caused by
putting the aerial in the loft. Also the degradation varies more with
time, water on the roof, etc. The difference between Group A and Group
CD channels is considerable. Group CD loft reception is unlikely to be
reliable. You need to put the aerial on the roof.

Bill
  #4  
Old October 7th 18, 08:35 AM posted to uk.tech.digital-tv
Brian Gaff
external usenet poster
 
Posts: 7,322
Default Strange reception issues on Ch55 and 56 from Rowridge

Is this an over the sea path and was it foggy or misty either before or
after?
Brian

--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Jeff Layman" wrote in message
news
I have just fitted a 36-element log-periodic
(
https://www.amazon.co.uk/AERIAL-LOG-...=optima+aerial)
in place of a Group A 18-element yagi so that I can get Com7/8. I am about
18 miles from Rowridge, apparently in a "good" reception area. The aerial
is in the loft, feeding an old Labgear 6-way distribution amp.

All the Group A channels come through at 10 signal strength and 10 signal
quality (Panasonic TV). But Com 7/8 on Ch 55 and 56 were only showing 7
strength and 3 -5 quality at best. Rarely the signal was lost for a second
or two with a black screen and "No signal" on the TV.

I have some old amps, and rather than fit a 26dB gain masthead amp (which
I thought might overload the Group A signals), I fitted a set-top 11dB amp
as a temporary "masthead" amp. This immediately improved the signal
received via Ch56. Strength was up to 9, and quality was now 7. But Ch55
was not as good. Signal strength was still 7 and quality at 3 or 4 with
the odd lost signal.

That was all about 30 minutes ago. Now Ch55 and 56 are both showing 9
strength and 9 quality! Maybe it's reception conditions today, but what
is/was going on with Com 7/8 reception? Why the marked difference between
Ch55 and 56 using the "masthead" amp?

--

Jeff



  #5  
Old October 7th 18, 08:40 AM posted to uk.tech.digital-tv
Brian Gaff
external usenet poster
 
Posts: 7,322
Default Strange reception issues on Ch55 and 56 from Rowridge

Depends very much on roof material and distance, but I'd agree, CD channels
were always an issue for me here with even a good log, though it was far
better than a yagoi for off beam signal pick up it only had around 10Db gain
but a yagi could be twice that.
Those old Multibeams were great, also rather big and heavy!
Brian

--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Bill Wright" wrote in message
news
On 06/10/2018 18:02, Jeff Layman wrote:

Maybe it's a device issue. I just retuned my Panasonic PVR and on the
quality of Ch56 (about 2) is considerably lower than that of Ch55 (about
5)!


The higher the channel number the more the signal degradation caused by
putting the aerial in the loft. Also the degradation varies more with
time, water on the roof, etc. The difference between Group A and Group CD
channels is considerable. Group CD loft reception is unlikely to be
reliable. You need to put the aerial on the roof.

Bill



  #6  
Old October 7th 18, 09:58 AM posted to uk.tech.digital-tv
Jeff Layman[_2_]
external usenet poster
 
Posts: 796
Default Strange reception issues on Ch55 and 56 from Rowridge

Yes, Rowridge is received across The Solent. Also, it was very wet
yesterday with a good bit of rain all day. However, this morning it is
dry and sunny. Despite that, about 10 minutes ago I was getting "No
service" on Ch55 and 56. But now there is no problem - good picture on
all Com7/8 channels. Signal strength is steady at 9, with signal quality
6 - 8. How can it vary so much over a few minutes? NB all this is
without a masthead amp connected.

I'll go up in the loft soon and play around a bit with the position of
the aerial. There is a lot of good info at
http://aerialsandtv.com/loftaerials.html#AttenuationLevelsThroughRoofs
on how changing position just a foot or two can affect reception
markedly. Failing any improvement there I'll try the amp again, as an
outside aerial isn't an option.

--

Jeff


On 07/10/18 08:35, Brian Gaff wrote:
Is this an over the sea path and was it foggy or misty either before or
after?
Brian



  #7  
Old October 7th 18, 12:26 PM posted to uk.tech.digital-tv
Jeff Layman[_2_]
external usenet poster
 
Posts: 796
Default Strange reception issues on Ch55 and 56 from Rowridge

On 07/10/18 09:58, Jeff Layman wrote:

I'll go up in the loft soon and play around a bit with the position of
the aerial.


Ten minutes in the loft and I am amazed at the difference a few inches
can make (no smut, please...). There seemed to be absolutely no logic
where to try the aerial (NB no amp used). I could go from a signal
quality of 1 or 2 and a very intermittent picture to a steady 9 with
barely 6 inches movement. I found it didn't matter where the aerial was
- I tried it high up just under a fluorescent light and 3 feet below it
resting on a cardboard box. Both gave a quality of 9 or 10, yet in
between the signal was lost almost entirely. In the end, for simplicity,
I simply lowered the aerial about 8 inches on the original mount. That
gave a quality of around 7 on Ch55 and 8 or 9 on 56. Strangely, in that
position it was pointing through breeze blocks rather than the tiles,
and from what I'd read I had expected that to give a poorer signal than
through tiles.

If the quality goes down again, perhaps due to adverse weather
conditions, it will be pretty simple to try other positions.

--

Jeff
  #8  
Old October 7th 18, 03:09 PM posted to uk.tech.digital-tv
Andrew[_6_]
external usenet poster
 
Posts: 229
Default Strange reception issues on Ch55 and 56 from Rowridge

On 06/10/2018 19:09, Bill Wright wrote:
Group CD loft reception is unlikely to be reliable. You need to put the
aerial on the roof.


My Group CD (MIdhurst) aerial blew down in the storm of 2000
and it has been suspended inside,between the roof trusses with garden
plastic coated wire ever since.

The house has North South aspect so it is up under the roofing felt
pointing at the 9 inch solid block wall that separates me from my
semi-d neighbour.

Works fine for all the major HD and other channels, but since
March getting the stuff on 33 is impossible, but strangely
enough the channels on 29 are watchable - mostly.
  #9  
Old October 7th 18, 08:56 PM posted to uk.tech.digital-tv
Ian Jackson[_7_]
external usenet poster
 
Posts: 171
Default Strange reception issues on Ch55 and 56 from Rowridge

In message , Jeff Layman
writes
On 07/10/18 09:58, Jeff Layman wrote:

I'll go up in the loft soon and play around a bit with the position of
the aerial.


Ten minutes in the loft and I am amazed at the difference a few inches
can make (no smut, please...). There seemed to be absolutely no logic
where to try the aerial (NB no amp used). I could go from a signal
quality of 1 or 2 and a very intermittent picture to a steady 9 with
barely 6 inches movement. I found it didn't matter where the aerial was
- I tried it high up just under a fluorescent light and 3 feet below it
resting on a cardboard box. Both gave a quality of 9 or 10, yet in
between the signal was lost almost entirely. In the end, for
simplicity, I simply lowered the aerial about 8 inches on the original
mount. That gave a quality of around 7 on Ch55 and 8 or 9 on 56.
Strangely, in that position it was pointing through breeze blocks
rather than the tiles, and from what I'd read I had expected that to
give a poorer signal than through tiles.

If the quality goes down again, perhaps due to adverse weather
conditions, it will be pretty simple to try other positions.

Lofts are often full of reflections. These create loads of frequency
dependent peaks and nulls in the RF field. Moving an aerial only
slightly can produce a great change of signal strength from channel to
channel - and this can be particularly marked if is high gain (and hence
highly directional). A low-gain aerial is often less-critical about
where you place it.
--
Ian
  #10  
Old October 7th 18, 11:14 PM posted to uk.tech.digital-tv
Bill Wright[_3_]
external usenet poster
 
Posts: 2,949
Default Strange reception issues on Ch55 and 56 from Rowridge

On 07/10/2018 09:58, Jeff Layman wrote:
Yes, Rowridge is received across The Solent. Also, it was very wet
yesterday with a good bit of rain all day. However, this morning it is
dry and sunny. Despite that, about 10 minutes ago I was getting "No
service" onĀ* Ch55 and 56. But now there is no problem - good picture on
all Com7/8 channels. Signal strength is steady at 9, with signal quality
6 - 8. How can it vary so much over a few minutes? NB all this is
without a masthead amp connected.

I'll go up in the loft soon and play around a bit with the position of
the aerial. There is a lot of good info at
http://aerialsandtv.com/loftaerials.html#AttenuationLevelsThroughRoofs
on how changing position just a foot or two can affect reception
markedly.


There's even better info he
http://www.wrightsaerials.tv/article...sat-201007.pdf

Failing any improvement there I'll try the amp again, as an
outside aerial isn't an option.

That will reduce outage times and durations but might not eliminate
them. Masthead amps can't do magic.

Bill
 




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