Diy Freesat

Brian Gaff wrote:

Which makes me think, is there any audio alignment device available
for dishes. Ie the tone pitch rises as the signal does that way,
once in the right basic positionn, it could be fine tuned with very
little gear and with crap eyesight.. grin.

Yes, that's how those cheap boxes you can get from B&Q work. The tone
volume changes, rather than the pitch. I've set up three dishes using
one. They are surprisingly sensitive if you are patient enough - just
the lightest pressure on the rim of the dish makes an audible
difference.

Obviously they don't know about the bit error rate, but I followed
Bill's advice and rotated the LNB until the cables came out at about
7o'clock, and this got me a good "signal quality" reading on the
satellite PVRs.

--
SteveT

rbel wrote:

dish
)
28.2 degrees Lnb )
___________________________________________)__
5 metre long exterior wall

Doesn't work with a monospace font!

A useful tool - many thanks. It confirms my thoughts that the dish
would need to be at right angles to the wall. If the dish is 60 cms
diameter does it need only a 60 cms wide field of view towards the
satellite, in other words will the adjacent wall interfere with the
signal?

Most dishes have offset feeds so the optical near field ( Rayleigh
distance) is elliptical.

Ideally, you don't want anything hotter than about minus 200 degrees C
(not sure what typical LNB noise temperatures are) within the beam
aperture, allowing for some divergence of the beam. However, LNBs are
designed to pick up very little from the edge of the dish, so they pick
up even less from its surroundings, so the actual aperture to consider
may be smaller than it at first looks.

Unfortunately, most of the theoretical stuff is for situations where the
signal or noise source is lot further away than the Rayleigh distance
(the point at which the beam tends to be conical, rather than
cylindrical, so, I'm not sure how far outside the aperture ellipse you
need to be for noise pickup to be negligible.

Also, an object that is outside of the beam can still diffract signals
towards or away from the dish, although, given the large aperture of the
dish in wavelengths, I suspect this is not nearly as significant as for
DTT aerials.

On Fri, 17 May 2013 09:29:21 +0200, Martin wrote:

I have decided to try a diy Freesat installation and the
first
question is, would a 54/60 cms dish mounted at right angles
to a 5
metre long wall, pointing 28.2 degrees east of south and
correctly
elevated, run into reception problems because its path is too
close to
the wall? The wall is higher than the top of the dish.



I went down this path last summer. The installer didn't have a fitting
that allowed the dish to be installed at 90 degrees to the wall. I
gave up and have the dish attached to the front of the house.

You might find this useful. http://www.astra2.org/dish.html

It is - many thanks
--
rbel

rbel wrote in message ...

I have decided to try a diy Freesat installation and the first
question is, would a 54/60 cms dish mounted at right angles to a 5
metre long wall, pointing 28.2 degrees east of south and correctly
elevated, run into reception problems because its path is too close to
the wall? The wall is higher than the top of the dish.

Iffy ASCII plan view

dish
)
28.2 degrees Lnb )
___________________________________________)__
5 metre long exterior wall
I take it that the relatively close proximity of tree foliage behind
the dish will not cause problems provided that it does not touch the
dish under any circumstances. The property is on the south coast so I
assume that a zone 2 dish will be more than adequate.
--
rbel

How sure are you about the angle of the wall?

The further east and to a lesser extent south) you are in the UK the more
likely this is to work. Try and mount the dish as far away from the wall as
practicable, bearing in mind that this will increase the leverage of the
wind load on the mount. Also mount high on the wall. If you use a 60cm
dish then a little shading on one side will probably not cause that much
difficulty.

On 17/05/2013 08:14, Brian Gaff wrote:
Which makes me think, is there any audio alignment device available for
dishes. Ie the tone pitch rises as the signal does that way, once in the
right basic positionn, it could be fine tuned with very little gear and with
crap eyesight.. grin.



£6 or £7 from ebay
http://www.ebay.co.uk/itm/Amiko-Satellite-Signal-Meter-Finder-for-Sky-Freesat-more-2-Year-Guarantee-/150981791675?pt=UK_Sound_Vision_Other&hash=item232 7374fbb

and how to use (including video)
http://www.satcure.co.uk/tech/satmeter.htm

--
mailto:news{at}admac(dot}myzen{dot}co{dot}uk

On Fri, 17 May 2013 13:37:19 +0100, "R. Mark Clayton"
wrote:


rbel wrote in message ...

I have decided to try a diy Freesat installation and the first
question is, would a 54/60 cms dish mounted at right angles to a 5
metre long wall, pointing 28.2 degrees east of south and correctly
elevated, run into reception problems because its path is too close to
the wall? The wall is higher than the top of the dish.

Iffy ASCII plan view

dish
)
28.2 degrees Lnb )
___________________________________________)__
5 metre long exterior wall
I take it that the relatively close proximity of tree foliage behind
the dish will not cause problems provided that it does not touch the
dish under any circumstances. The property is on the south coast so I
assume that a zone 2 dish will be more than adequate.
--
rbel

How sure are you about the angle of the wall?

I think I have got this right. I placed the straight edge of a decent
Silva map reading compass against the wall in a couple of places, set
the dial to north and read off the bearing which was 148 degrees. As
this is 32 degrees east of south I assume that would give me, in
theory, approximately 4 degrees of leeway. The dishpointer.com site
suggested by MikeS gives an indication that this not far off.


The further east and to a lesser extent south) you are in the UK the more
likely this is to work. Try and mount the dish as far away from the wall as
practicable, bearing in mind that this will increase the leverage of the
wind load on the mount. Also mount high on the wall. If you use a 60cm
dish then a little shading on one side will probably not cause that much
difficulty.


The dish could be mounted at a centre height of 3.4 metres above
ground level with a hedge maintained at 3 metres tall about 12 metres
away in the direction of the satellite.

As we are subject to very high winds here (on top of a hill near the
South Devon coast) I would want to mount the dish as close as possible
to wall.

Using a 54 cms dish would reduce the windage by around 20% and I
imagine that it would not have a significant impact on the signal
reception.
--
rbel

rbel wrote in message
...
On Fri, 17 May 2013 13:37:19 +0100, "R. Mark Clayton"
wrote:


rbel wrote in message
. ..

I have decided to try a diy Freesat installation and the
first
question is, would a 54/60 cms dish mounted at right angles
to a 5
metre long wall, pointing 28.2 degrees east of south and
correctly
elevated, run into reception problems because its path is too
close to
the wall? The wall is higher than the top of the dish.

Iffy ASCII plan view

dish
)
28.2 degrees Lnb
)
___________________________________________)__
5 metre long exterior wall
I take it that the relatively close proximity of tree foliage
behind
the dish will not cause problems provided that it does not
touch the
dish under any circumstances. The property is on the south
coast so I
assume that a zone 2 dish will be more than adequate.
--
rbel

How sure are you about the angle of the wall?

I think I have got this right. I placed the straight edge of a
decent
Silva map reading compass against the wall in a couple of
places, set
the dial to north and read off the bearing which was 148
degrees. As
this is 32 degrees east of south I assume that would give me,
in
theory, approximately 4 degrees of leeway. The dishpointer.com
site
suggested by MikeS gives an indication that this not far off.


The further east and to a lesser extent south) you are in the
UK the more
likely this is to work. Try and mount the dish as far away
from the wall as
practicable, bearing in mind that this will increase the
leverage of the
wind load on the mount. Also mount high on the wall. If you
use a 60cm
dish then a little shading on one side will probably not cause
that much
difficulty.


The dish could be mounted at a centre height of 3.4 metres
above
ground level with a hedge maintained at 3 metres tall about 12
metres
away in the direction of the satellite.

As we are subject to very high winds here (on top of a hill
near the
South Devon coast) I would want to mount the dish as close as
possible
to wall.

Using a 54 cms dish would reduce the windage by around 20% and
I
imagine that it would not have a significant impact on the
signal
reception.
--


This is a very good site - developed I think by one of the
contributors to this NG. It will show you an OS map line for the
dish and a Google maps satellite view. You can move the end of
the line to exactly where you want it on your house.

http://www.macfh.co.uk/JavaJive/Audi...Calculator.php


--
Woody

harrogate three at ntlworld dot com

On 17/05/2013 18:39, rbel wrote:
On Fri, 17 May 2013 13:37:19 +0100, "R. Mark Clayton"
wrote:


rbel wrote in message ...

I have decided to try a diy Freesat installation and the first
question is, would a 54/60 cms dish mounted at right angles to a 5
metre long wall, pointing 28.2 degrees east of south and correctly
elevated, run into reception problems because its path is too close to
the wall? The wall is higher than the top of the dish.

Iffy ASCII plan view

dish
)
28.2 degrees Lnb )
___________________________________________)__
5 metre long exterior wall
I take it that the relatively close proximity of tree foliage behind
the dish will not cause problems provided that it does not touch the
dish under any circumstances. The property is on the south coast so I
assume that a zone 2 dish will be more than adequate.
--
rbel

How sure are you about the angle of the wall?

I think I have got this right. I placed the straight edge of a decent
Silva map reading compass against the wall in a couple of places, set
the dial to north and read off the bearing which was 148 degrees. As
this is 32 degrees east of south I assume that would give me, in
theory, approximately 4 degrees of leeway. The dishpointer.com site
suggested by MikeS gives an indication that this not far off.


The further east and to a lesser extent south) you are in the UK the more
likely this is to work. Try and mount the dish as far away from the wall as
practicable, bearing in mind that this will increase the leverage of the
wind load on the mount. Also mount high on the wall. If you use a 60cm
dish then a little shading on one side will probably not cause that much
difficulty.


The dish could be mounted at a centre height of 3.4 metres above
ground level with a hedge maintained at 3 metres tall about 12 metres
away in the direction of the satellite.

As we are subject to very high winds here (on top of a hill near the
South Devon coast) I would want to mount the dish as close as possible
to wall.

Using a 54 cms dish would reduce the windage by around 20% and I
imagine that it would not have a significant impact on the signal
reception.


At a random location in Plymouth, Dishpointer gives an
azimuth reading for the satellites at 28.2E of
140.6° true
143.2° magnetic
which would put them behind the wall at 148° magnetic.

I had an installation similar to this at my last
house, with the dish perpendicular to the wall. The
biggest problem was finding a bracket that would let
me mount it this way. Luckily, my neighbour had a
spare cranked mast in his garage.

54cm dish size should be plenty at your location, but
a smaller one might be easier to install. In your
case, the dish would need to be mounted at least
half-a-metre off the wall (by my simple - but not
necessarily correct - trig calculation) in order to
get the azimuth clear. I don't know what effect, if
any, wall reflections or refractions would have on the
signal.

On 17/05/2013 18:39, rbel wrote:


I think I have got this right. I placed the straight edge of a decent
Silva map reading compass against the wall in a couple of places, set
the dial to north and read off the bearing which was 148 degrees. As
this is 32 degrees east of south I assume that would give me, in
theory, approximately 4 degrees of leeway. The dishpointer.com site
suggested by MikeS gives an indication that this not far off.


In case you are not aware, you can drag the end of the green line to the
satellite to the intended position of your dish and then zoom in on the
map or satellite photo.



--
mailto:news{at}admac(dot}myzen{dot}co{dot}uk

On Sat, 18 May 2013 05:30:42 +0100, alan
wrote:

On 17/05/2013 18:39, rbel wrote:


I think I have got this right. I placed the straight edge of a decent
Silva map reading compass against the wall in a couple of places, set
the dial to north and read off the bearing which was 148 degrees. As
this is 32 degrees east of south I assume that would give me, in
theory, approximately 4 degrees of leeway. The dishpointer.com site
suggested by MikeS gives an indication that this not far off.


In case you are not aware, you can drag the end of the green line to the
satellite to the intended position of your dish and then zoom in on the
map or satellite photo.

I had done this using dishpointer and JavaJive's app and the line is
at best parallel to the wall and worst fractionally the wrong side of
it.

Given this and the advice that the dish would need to stand off the
wall by more than I would wish, leads me to think that I should
endeavour to find another location for it, which is not easy. I may
end up needing to use the flat panel Selfsat H30D2 antenna mentioned
in a previous thread, on a more exposed SSE facing wall.

Many thanks for the advice.
--
rbel