Sutton and Lichfield

http://www.paras.org.uk/

No, the temporary mux is of no interest, since there is no terrestrial
HD in the building and won't be for the next year. However it did
cross my mind that it could cause a problem had the circumstances been
different.

The problem was a few old tellys that needed analogue C5. In the end
we decided to scrap them. That was a better use of money than a
seperate aerial and channel filter!

Bill



I had the same problem many years ago in Shirley, Southampton.

I fitted a new aerial and combiner for a mate to receive analogue C5 from
Fawley as his Rowridge aerial was only able to provide ghosty mush from
Rowridge OR Fawley. As I recall they were about 45 degrees apart.

In article
..com, scribeth thus
On Apr 27, 9:00*am, (Richard Tobin) wrote:
In article ,

wrote:
I've been working today at Burntwood, Staffs. SC and Lichfield are
both clearly visible. I haven't measured it but I'd guess they're 5 or
6 miles away. They are about 35deg apart. It is not possible to
receive the TV signals from both on one aerial, without compromising
quality. What a silly state of affairs.

Yes, I've been complaining about geometry for a long time, but no one
ever does anything about it. *If we had a few more dimensions, we could
ensure that everywhere was within walking distance of everywhere else.

-- Richard

Geometry doesn't worry me; I'm used to it now. My complaint was about
two main stations with the same nominal coverage area being so far
apart. Not a matter of universal physical law, like geometry; just a
matter of human affairs being imperfectly conducted.

Bill

Umm.. In the scheme of things these days, are Sutton C and Lichfield
both carrying DTV or is Lichfield channel 5 analogue only and will close
down before that much longer?.

So there shouldn't be a problem any longer?...
--
Tony Sayer

On Tue, 27 Apr 2010 21:23:44 +0100, "Doctor D"
wrote:


http://www.paras.org.uk/

No, the temporary mux is of no interest, since there is no terrestrial
HD in the building and won't be for the next year. However it did
cross my mind that it could cause a problem had the circumstances been
different.

The problem was a few old tellys that needed analogue C5. In the end
we decided to scrap them. That was a better use of money than a
seperate aerial and channel filter!

Bill



I had the same problem many years ago in Shirley, Southampton.

I fitted a new aerial and combiner for a mate to receive analogue C5 from
Fawley as his Rowridge aerial was only able to provide ghosty mush from
Rowridge OR Fawley. As I recall they were about 45 degrees apart.

That was a very common problem. Many people within the potential
service area of Fawley couldn't get it with their existing aerials on
Rowridge, and didn't want C5 enough to pay for additional aerials.

In article , Java Jive
scribeth thus
It'll be carrying SC's DVB-T2/HD mux at least until DSO. I suspect
that after DSO it will indeed drop out of use, but I'm sure Mark will
be along in a while to confirm or correct.

Umm.. So whys it carrying that instead of SC.?. Aerial space or cost?..

--
Tony Sayer

In article ,
Brian Gaff wrote:

If they are only that far away, you almost need a very wide beam width
Arial. I recall, many moons ago achieving this by actually sawing off an
Antiference Arial so there were only two directors left!

Are you using speech input? It seems to think you're talking about
a font rather than an antenna!

-- Richard

On 27/04/2010 22:52, lid wrote:

I fitted a new aerial and combiner for a mate to receive analogue C5 from
Fawley as his Rowridge aerial was only able to provide ghosty mush from
Rowridge OR Fawley. As I recall they were about 45 degrees apart.

That was a very common problem. Many people within the potential
service area of Fawley couldn't get it with their existing aerials on
Rowridge, and didn't want C5 enough to pay for additional aerials.

I actually lived where both Fawley and Rowridge were to within a gnat's
difference on the same bearing. However, that was no good either,
because BBC 1 on E31 came banging in about 20dB above C5 on E34.
Therefore BBC 1 would 'splash' over C5. I faffed about with filters etc
for ages, and finally obtained satisfactory results, however the next
day C5 popped up crystal clear on Astra 19.2, so I needn't have bothered
! I thought at the time, how handy it would be to have the other four
channels on satellite too ;-)


--
Mark
Please replace invalid and invalid with gmx and net to reply.

http://www.paras.org.uk/

No, but the spellcucker was on auto that time.

Sorry bout that.

One has no idea when the word is read if its been got at of course!

Brian

--
Brian Gaff -
Note:- In order to reduce spam, any email without 'Brian Gaff'
in the display name may be lost.
Blind user, so no pictures please!
"Richard Tobin" wrote in message
...
In article ,
Brian Gaff wrote:

If they are only that far away, you almost need a very wide beam width
Arial. I recall, many moons ago achieving this by actually sawing off an
Antiference Arial so there were only two directors left!

Are you using speech input? It seems to think you're talking about
a font rather than an antenna!

-- Richard

In message , Brian Gaff
writes
If they are only that far away, you almost need a very wide beam width
Arial. I recall, many moons ago achieving this by actually sawing off an
Antiference Arial so there were only two directors left!

I'm sort-of guessing, but I would have thought that you could obtain a
wide beamwidth by adding the polar diagrams of two medium-gain,
identical aerials. These would be co-located, but mounted with the
required angle of 35 degrees between them (each pointing at its required
transmitter).

The aerials would need to be combined using feeders of identical
lengths. The actual lengths would not matter, so the two feeders could
be brought to an accessible place, where the combiner would be located.

At only 5 or 6 miles from the transmitters, there should be more than
sufficient signal, so the combiner could be a bit lossy. A standard TV
2-way splitter (reversed) could be used, incurring a loss of around
4dB*. Obviously, this technique will only be 'sound' for relatively
narrow angles. With a wider beamwidth, there's a greater risk of
ghosting.

Later on, when one of one of the signals was no longer required, the
unwanted feed could be disconnected from the combiner, restoring the
polar diagram to that of a single aerial. The unused port can be
terminated, or the combiner removed and a barrel put in.

*It would only as high as 4dB if two different signals were being
combined. If the two aerials were being used to obtain more gain, with
no angle between them, two essentially identical signals would be
presented to the combiner input ports. In this case, there would be no
power loss in the combiner (other then the unavoidable 1dB or so in the
transformers).

Or am I talking rubbish?
--
Ian

On Wed, 28 Apr 2010 05:11:30 +0100, "Brian Gaff"
wrote:

Yes, what youn need here is the spherical version of a mobious loop.

Brian

For sale: Klein bottle. Apply within.
--
Tim

On Apr 28, 2:11*pm, Ian Jackson
wrote:
I'm sort-of guessing, but I would have thought that you could obtain a
wide beamwidth by adding the polar diagrams of two medium-gain,
identical aerials. These would be co-located, but mounted with the
required angle of 35 degrees between them (each pointing at its required
transmitter).

They would have to have the dipoles in the same vertical axis. One
dipole would have to be exactly above the other, and they would have
to be fairly close together.

This is how some tx aerials achieve the desired polar response.

In Scotland somewhere there used to be a self helf where they'd tried
this technique but had put the aerials side by side. The result was a
series of nulls across the field, each null being 'infinitely' deep.
Basically, as you went down the street every so often there was a
house with zero reception.

Bill