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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.

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  #21  
Old June 7th 17, 02:54 AM posted to uk.tech.digital-tv
Bill Wright[_3_]
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On 31/05/2017 09:56, Mark Carver wrote:

I've noticed quite a few more logs generally. The pain with Rowridge
is COM 7 and 8 are HP only, so you lose them if you go VP. VP is 6dB
up on HP for the other 6 muxes, and you need it in the overlap areas
with Stockland Hill in particular.

So no installer can use VP because he'd be risking a call back. No COM 7
and 8. The VP is useless then.

Bill
  #22  
Old June 7th 17, 06:41 AM posted to uk.tech.digital-tv
Scott[_2_]
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On Wed, 7 Jun 2017 03:54:00 +0100, Bill Wright
wrote:

On 31/05/2017 09:56, Mark Carver wrote:

I've noticed quite a few more logs generally. The pain with Rowridge
is COM 7 and 8 are HP only, so you lose them if you go VP. VP is 6dB
up on HP for the other 6 muxes, and you need it in the overlap areas
with Stockland Hill in particular.

So no installer can use VP because he'd be risking a call back. No COM 7
and 8. The VP is useless then.

Can you get a 'mixed polarisation' aerial to pick up both?
  #23  
Old June 7th 17, 08:17 AM posted to uk.tech.digital-tv
Mark Carver[_2_]
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On 07/06/2017 07:41, Scott wrote:
On Wed, 7 Jun 2017 03:54:00 +0100, Bill Wright
wrote:

On 31/05/2017 09:56, Mark Carver wrote:

I've noticed quite a few more logs generally. The pain with Rowridge
is COM 7 and 8 are HP only, so you lose them if you go VP. VP is 6dB
up on HP for the other 6 muxes, and you need it in the overlap areas
with Stockland Hill in particular.

So no installer can use VP because he'd be risking a call back. No COM 7
and 8. The VP is useless then.

Can you get a 'mixed polarisation' aerial to pick up both?


That would be counter productive, because the reason the main 6 muxes
are VP, is because of CCI in the HP plane



--
Mark
Please replace invalid and invalid with gmx and net to reply.
  #24  
Old June 7th 17, 05:09 PM posted to uk.tech.digital-tv
Scott[_2_]
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On Wed, 7 Jun 2017 09:17:56 +0100, Mark Carver
wrote:

On 07/06/2017 07:41, Scott wrote:
On Wed, 7 Jun 2017 03:54:00 +0100, Bill Wright
wrote:

On 31/05/2017 09:56, Mark Carver wrote:

I've noticed quite a few more logs generally. The pain with Rowridge
is COM 7 and 8 are HP only, so you lose them if you go VP. VP is 6dB
up on HP for the other 6 muxes, and you need it in the overlap areas
with Stockland Hill in particular.

So no installer can use VP because he'd be risking a call back. No COM 7
and 8. The VP is useless then.

Can you get a 'mixed polarisation' aerial to pick up both?


That would be counter productive, because the reason the main 6 muxes
are VP, is because of CCI in the HP plane


I appreciate that is the position here, but in general I wondered if
such an aerial would exist. Just out of curiosity.
  #25  
Old June 8th 17, 05:14 AM posted to uk.tech.digital-tv
Bill Wright[_3_]
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Posts: 1,917
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On 07/06/2017 07:41, Scott wrote:
On Wed, 7 Jun 2017 03:54:00 +0100, Bill Wright
wrote:

On 31/05/2017 09:56, Mark Carver wrote:

I've noticed quite a few more logs generally. The pain with Rowridge
is COM 7 and 8 are HP only, so you lose them if you go VP. VP is 6dB
up on HP for the other 6 muxes, and you need it in the overlap areas
with Stockland Hill in particular.

So no installer can use VP because he'd be risking a call back. No COM 7
and 8. The VP is useless then.

Can you get a 'mixed polarisation' aerial to pick up both?



There wouldn't be any point really. There's also the question of the
phase relationship between the two polarisations. I don't know what the
transmission arrangements are but if the two polarisations are
transmitted from seperate antennas I would assume that the phase
relationship at any point where they can both be received would be
random. This would lead to reinforcement or cancellation, again at random.

Bill
  #26  
Old June 8th 17, 06:02 AM posted to uk.tech.digital-tv
Bill Wright[_3_]
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Posts: 1,917
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On 07/06/2017 18:09, Scott wrote:
On Wed, 7 Jun 2017 09:17:56 +0100, Mark Carver
wrote:

On 07/06/2017 07:41, Scott wrote:
On Wed, 7 Jun 2017 03:54:00 +0100, Bill Wright
wrote:

On 31/05/2017 09:56, Mark Carver wrote:

I've noticed quite a few more logs generally. The pain with Rowridge
is COM 7 and 8 are HP only, so you lose them if you go VP. VP is 6dB
up on HP for the other 6 muxes, and you need it in the overlap areas
with Stockland Hill in particular.

So no installer can use VP because he'd be risking a call back. No COM 7
and 8. The VP is useless then.

Can you get a 'mixed polarisation' aerial to pick up both?


That would be counter productive, because the reason the main 6 muxes
are VP, is because of CCI in the HP plane


I appreciate that is the position here, but in general I wondered if
such an aerial would exist. Just out of curiosity.

For receiving circular (etc) polarisation yes, but for simultaneous
reception of two orthoganal polarisations, I dunno.

I've seen arrays with two yagis mounted on the same boom at right
angles, something to do with weather satellites maybe, but whether
there's a common feedpoint or two seperate ones, I dunno.

Bill
  #27  
Old June 8th 17, 06:20 PM posted to uk.tech.digital-tv
Scott[_2_]
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Posts: 1,260
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On Thu, 8 Jun 2017 06:14:45 +0100, Bill Wright
wrote:

On 07/06/2017 07:41, Scott wrote:
On Wed, 7 Jun 2017 03:54:00 +0100, Bill Wright
wrote:

On 31/05/2017 09:56, Mark Carver wrote:

I've noticed quite a few more logs generally. The pain with Rowridge
is COM 7 and 8 are HP only, so you lose them if you go VP. VP is 6dB
up on HP for the other 6 muxes, and you need it in the overlap areas
with Stockland Hill in particular.

So no installer can use VP because he'd be risking a call back. No COM 7
and 8. The VP is useless then.

Can you get a 'mixed polarisation' aerial to pick up both?



There wouldn't be any point really.


Could it not double the signal in a fringe area?

There's also the question of the
phase relationship between the two polarisations. I don't know what the
transmission arrangements are but if the two polarisations are
transmitted from seperate antennas I would assume that the phase
relationship at any point where they can both be received would be
random. This would lead to reinforcement or cancellation, again at random.

I think you have answered my first question.
  #28  
Old June 9th 17, 02:15 AM posted to uk.tech.digital-tv
Bill Wright[_3_]
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Posts: 1,917
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On 08/06/2017 19:20, Scott wrote:
Can you get a 'mixed polarisation' aerial to pick up both?



There wouldn't be any point really.


Could it not double the signal in a fringe area?

There's also the question of the
phase relationship between the two polarisations. I don't know what the
transmission arrangements are but if the two polarisations are
transmitted from seperate antennas I would assume that the phase
relationship at any point where they can both be received would be
random. This would lead to reinforcement or cancellation, again at random.

I think you have answered my first question.


Yes, but we could pursue it further just for fun! If the outputs of two
aerials are of identical strength and are combined there is, in
practice, an increase in signal level of 2 to 3dB. But for this to be
achieved the signals must be perfectly in phase at the combining point.
This has to be across the full bandwidth received. It's hard enough to
get that right when the phase relationship of the signal fields at the
two aerial locations is locked. I can't imagine how it would work out if
it wasn't (because the two aerials were receiving the same signals but
from different transmission aerials.)

Bill
 




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