I am trying to see if I could have a satellite dish to serve my Freesat
box. As far as I can see from Googling I need to allow 5 degrees variation
so point it at 247 degrees. Does this seem correct for Alderholt (3 mile
west of Fordingbridge, Hampshire)? At this stage I'm just trying to see if it's feasible with trees/obstacle etc.
Will an aerial installer be able to fit me a wideband Sky dish without signing me up to Sky?
I am trying to see if I could have a satellite dish to serve my Freesat
box. As far as I can see from Googling I need to allow 5 degrees
variation so point it at 247 degrees.
Does this seem correct for
Alderholt (3 mile west of Fordingbridge, Hampshire)? At this stage I'm
just trying to see if it's feasible with trees/obstacle etc.
Will an aerial installer be able to fit me a wideband Sky dish without signing me up to Sky?
Jeff Gaines wrote:
I am trying to see if I could have a satellite dish to serve my Freesat box. As far as I can see from Googling I need to allow 5 degrees
variation
5° seems a lot.
so point it at 247 degrees. Does this seem correct for Alderholt (3
mile west of Fordingbridge, Hampshire)
Dishpointer says 143.3°
I am trying to see if I could have a satellite dish to serve my Freesat box. As
far as I can see from Googling I need to allow 5 degrees variation
so point it at 247 degrees. Does this seem correct for Alderholt (3 mile west of Fordingbridge, Hampshire)
On 15/04/2022 in message <xn0ngn6up2b8l8a003@news.individual.net> Jeff
Gaines wrote:
I am trying to see if I could have a satellite dish to serve my Freesat >box. As far as I can see from Googling I need to allow 5 degrees
variation so point it at 247 degrees. Does this seem correct for
Alderholt (3 mile west of Fordingbridge, Hampshire)? At this stage I'm
just trying to see if it's feasible with trees/obstacle etc.
Will an aerial installer be able to fit me a wideband Sky dish without >signing me up to Sky?
Thanks for the replies :-)
I screwed the maths up, I think the answer is 153 degrees (including an allowance of 5 for variation) as follows:
180 - 23 - 5 = 153.
I think I took the variation off twice then wrote 247 instead of 147,
good job I'm not flying to the moon!
I found:
"The most common satellites in the UK are the Astra 2 satellites at 28.2E
and Eurobird at 28.5E."
However, that's meaningless to me, the compass starts at 0 and ends at
359 or 360 depending how pedantic you want to be.
I suggested a Sky dish as with the wideband (Sky Q) version I can record
4 channels (from memory) at a time. Doesn't happen very often that
there's 4 channels worth recording but does occasionally and as I'm
starting from scratch I might as well do it properly. If there's a non
Sky version that will do fine.
There's only one neighbour with a dish, it's mounted on an extension roof
and points at the house roof so may not be too effective.
There is a large tree which I think may be in the way which is why I want
to get a rough idea before calling an installer in.
Thanks again.
I am trying to see if I could have a satellite dish to serve my Freesat
box. As far as I can see from Googling I need to allow 5 degrees variation
so point it at 247 degrees. Does this seem correct for Alderholt (3 mile
west of Fordingbridge, Hampshire)? At this stage I'm just trying to see if >it's feasible with trees/obstacle etc.
Will an aerial installer be able to fit me a wideband Sky dish without >signing me up to Sky?
I am trying to see if I could have a satellite dish to serve my Freesat
box. As far as I can see from Googling I need to allow 5 degrees
variation so point it at 247 degrees. Does this seem correct for
Alderholt (3 mile west of Fordingbridge, Hampshire)? At this stage I'm
just trying to see if it's feasible with trees/obstacle etc.
Will an aerial installer be able to fit me a wideband Sky dish without signing me up to Sky?
williamwright wrote:
you don't want a wideband LNB. You just need an ordinary LNB with four
outputs. Two are spare and you run two cables from the others to your
freesat box. Then you can record as many channels as you want,
depending on the box's capabilities.
He *might* want a wideband, or at least a combined wideband + universal.
if feeding 2x universal into a recorder. it will depend whether all the wanted recordings happen to be on transponders in the same "quarter" of
the HH/HV/LH/LV combinations of frequency and polarisation.
In article <xn0ngn9gx2eqn5b004@news.individual.net>, Jeff Gaines <jgaines_newsid@yahoo.co.uk> wrote:
On 15/04/2022 in message <xn0ngn6up2b8l8a003@news.individual.net> Jeff
Gaines wrote:
I am trying to see if I could have a satellite dish to serve my Freesat
box. As far as I can see from Googling I need to allow 5 degrees
variation so point it at 247 degrees. Does this seem correct for
Alderholt (3 mile west of Fordingbridge, Hampshire)? At this stage I'm
just trying to see if it's feasible with trees/obstacle etc.
Will an aerial installer be able to fit me a wideband Sky dish without
signing me up to Sky?
Thanks for the replies :-)
I screwed the maths up, I think the answer is 153 degrees (including an
allowance of 5 for variation) as follows:
180 - 23 - 5 = 153.
I think I took the variation off twice then wrote 247 instead of 147,
good job I'm not flying to the moon!
I found:
"The most common satellites in the UK are the Astra 2 satellites at 28.2E
and Eurobird at 28.5E."
However, that's meaningless to me, the compass starts at 0 and ends at
359 or 360 depending how pedantic you want to be.
I suggested a Sky dish as with the wideband (Sky Q) version I can record
4 channels (from memory) at a time. Doesn't happen very often that
there's 4 channels worth recording but does occasionally and as I'm
starting from scratch I might as well do it properly. If there's a non
Sky version that will do fine.
The dish won't record anything. You need a suitable recording device. If
you want a Sky device, then you will need a subscription.
There's only one neighbour with a dish, it's mounted on an extension roof
and points at the house roof so may not be too effective.
It probably looks over the house roof. Dishes, in general, either work - or they don't.
There is a large tree which I think may be in the way which is why I want
to get a rough idea before calling an installer in.
Thanks again.
you don't want a wideband LNB. You just need an ordinary LNB with four outputs.
Two are spare and you run two cables from the others to your freesat box. Then
you can record as many channels as you want, depending on the box's capabilities.
I am trying to see if I could have a satellite dish to serve my Freesat
box. As far as I can see from Googling I need to allow 5 degrees
variation so point it at 247 degrees. Does this seem correct for
Alderholt (3 mile west of Fordingbridge, Hampshire)? At this stage I'm
just trying to see if it's feasible with trees/obstacle etc.
Will an aerial installer be able to fit me a wideband Sky dish without signing me up to Sky?
Stand at the proposed dish location and face due south, then divert your gaze about 28deg to the east of due south.
I need to allow 5 degrees variation
On 15/04/2022 09:51, Jeff Gaines wrote:
I am trying to see if I could have a satellite dish to serve my Freesat >>box. As far as I can see from Googling I need to allow 5 degrees
variation so point it at 247 degrees. Does this seem correct for
Alderholt (3 mile west of Fordingbridge, Hampshire)? At this stage I'm
just trying to see if it's feasible with trees/obstacle etc.
Will an aerial installer be able to fit me a wideband Sky dish without >>signing me up to Sky?
To see if you have any obstructions
Go to https://www.dishpointer.com/
In the fist box type in your post code
In the second box select the satellite. 28.2E Astra 2E, 2F, 2G for Freesat >Press the search button
You should get a map or satellite image with a green line. This line
points to the satellite.
The map or satellite image is a user selectable option
Click on the green blob at the end of the green line and drag it to you
house or location where you are going to install the dish. You can zoom in >the map or satellite image.
There is a tick box labelled "show obstacle (line of sight checker)"
This puts a moveable red blob on the green line indicating the height you >need to clear any nearby objects.
Any installer should be able to install a sky type dish for any purpose.
It's not the dish that is wideband but the LNB attached to it.
If yo already have an old Freesat box it will not support a wideband LNB - >just a universal LNB - but go for a quad universal LNB.
It's only very recently the some Freesat boxes have supported the sky >wideband LNB or check your box before going down this (wideband) route.
It shows the tree in my next door but one neighbour's garden with the green line apparently clear of it, using the compass on my 'phone it's marginal - 135 degrees clears it, above that it gets dodgy. I probably ought to wait for the leaves to come out before I get an installer in.
Jeff Gaines wrote:
I am trying to see if I could have a satellite dish to serve my Freesat box. As5° seems a lot.
far as I can see from Googling I need to allow 5 degrees variation
so point it at 247 degrees. Does this seem correct for Alderholt (3 mile westDishpointer says 143.3°
of Fordingbridge, Hampshire)
On 15/04/2022 12:05, williamwright wrote:
Stand at the proposed dish location and face due south, then divert your gaze about 28deg to the east of due south.That would only be true fractionally away from the North pole, and if
the Clark belt was at, effectively, infinite distance, which it isn't.
(You have to be fractionally away, otherwise every direction is South!) Given the 143° suggested elsewhere, you'd be quite a long way out.
You also have to consider elevation <http://downloads.falcontechnical.co.uk/easyfind/Finding_the_elevation_for_your_location.pdf>,
as well as azimuth.
I'm surprised that there is no map of required azimuths that I can find, just calculators. There are maps for elevation and for polarisation
skew. It looks like the main approach is to set the elevation then
simply sweep to find the azimuth.
On 15/04/2022 09:51, Jeff Gaines wrote:
I need to allow 5 degrees variationMay be my misunderstanding but FWIW the magnetic variation from grid
North where you are is less than half a degree West[1]. You are close to
the grid origin at 2 degrees west so the variation from true North will
be much the same.
[1] http://www.geomag.bgs.ac.uk/data_service/models_compass/gma_calc.html
--
Robin
reply-to address is (intended to be) valid
On 15/04/2022 in message <xn0ngn6up...@news.individual.net> Jeff
Gaines wrote:
I am trying to see if I could have a satellite dish to serve my Freesat >box. As far as I can see from Googling I need to allow 5 degrees variation >so point it at 247 degrees. Does this seem correct for Alderholt (3 mile >west of Fordingbridge, Hampshire)? At this stage I'm just trying to see if >it's feasible with trees/obstacle etc.
Will an aerial installer be able to fit me a wideband Sky dish without >signing me up to Sky?
Thanks for the replies :-)
I screwed the maths up, I think the answer is 153 degrees (including an allowance of 5 for variation) as follows:
180 - 23 - 5 = 153.
I think I took the variation off twice then wrote 247 instead of 147, good job I'm not flying to the moon!
I found:
"The most common satellites in the UK are the Astra 2 satellites at 28.2E
and Eurobird at 28.5E."
However, that's meaningless to me, the compass starts at 0 and ends at 359
or 360 depending how pedantic you want to be.
I suggested a Sky dish as with the wideband (Sky Q) version I can record 4 channels (from memory) at a time. Doesn't happen very often that there's 4 channels worth recording but does occasionally and as I'm starting from scratch I might as well do it properly. If there's a non Sky version that will do fine.
There's only one neighbour with a dish, it's mounted on an extension roof
and points at the house roof so may not be too effective. There is a large tree which I think may be in the way which is why I want to get a rough
idea before calling an installer in.
Thanks again.
--
Jeff Gaines Dorset UK
There are 3 types of people in this world. Those who can count, and those
who can't.
Jeff Gaines wrote:
It shows the tree in my next door but one neighbour's garden with the green line apparently clear of it, using the compass on my 'phone it's marginal - 135 degrees clears it, above that it gets dodgy. I probably ought to wait for
the leaves to come out before I get an installer in.
Try it yourself at ground-level?
On Friday, 15 April 2022 at 10:45:32 UTC+1, Andy Burns wrote:
Jeff Gaines wrote:
I am trying to see if I could have a satellite dish to serve my5° seems a lot.
Freesat box. As far as I can see from Googling I need to allow 5
degrees variation
It is - the satellites are 3° apart and alternate polarity, so you would
be looking at the next but one.
so point it at 247 degrees. Does this seem correct for Alderholt (3Dishpointer says 143.3°
mile west of Fordingbridge, Hampshire)
Both these figures seem improbable. The satellite is over 28.2E and Aldershot is less than 1° W, so by my calculation the dish would point approximately 146-147°
Centuries ago the world pretty much agreed that Greenwich would be the prime Meridien. Longitudes to the east would be written nnE and to the west nnW, although these days some write -nn for east.
The satellites are geostationary over the equator so their position is given as the latitude they are over,
For a satellite well to the east or west of your own position, you have to make allowance for the angle between you and the satellite (for 28E from 1W about five degrees,
On 15/04/2022 in message <jbt7c8F6iu4U1@mid.individual.net> alan_m wrote:
On 15/04/2022 09:51, Jeff Gaines wrote:
I am trying to see if I could have a satellite dish to serve my
Freesat box. As far as I can see from Googling I need to allow 5
degrees variation so point it at 247 degrees. Does this seem correct
for Alderholt (3 mile west of Fordingbridge, Hampshire)? At this
stage I'm just trying to see if it's feasible with trees/obstacle etc.
Will an aerial installer be able to fit me a wideband Sky dish
without signing me up to Sky?
To see if you have any obstructions
Go to https://www.dishpointer.com/
In the fist box type in your post code
In the second box select the satellite. 28.2E Astra 2E, 2F, 2G for
Freesat
Press the search button
You should get a map or satellite image with a green line. This line
points to the satellite.
The map or satellite image is a user selectable option
Click on the green blob at the end of the green line and drag it to
you house or location where you are going to install the dish. You can
zoom in the map or satellite image.
There is a tick box labelled "show obstacle (line of sight checker)"
This puts a moveable red blob on the green line indicating the height
you need to clear any nearby objects.
Any installer should be able to install a sky type dish for any
purpose. It's not the dish that is wideband but the LNB attached to it.
If yo already have an old Freesat box it will not support a wideband
LNB - just a universal LNB - but go for a quad universal LNB.
It's only very recently the some Freesat boxes have supported the sky
wideband LNB or check your box before going down this (wideband) route.
That is brilliant, thank you :-)
It shows the tree in my next door but one neighbour's garden with the
green line apparently clear of it, using the compass on my 'phone it's marginal - 135 degrees clears it, above that it gets dodgy. I probably
ought to wait for the leaves to come out before I get an installer in.
You also need the declination angle for the dish at the latitude and longitude for your location.
For a satellite overhead it is 90-latitude° and about 6-8°. So for Aldershot it is 29° - declination, which depends slightly on which satellite you are trying to recieve.
It shows the tree in my next door but one neighbour's garden with the
green line apparently clear of it, using the compass on my 'phone it's >>marginal - 135 degrees clears it, above that it gets dodgy. I probably >>ought to wait for the leaves to come out before I get an installer in.
What does the red blob tell you:) That will give the height the tree
needs to be to block the signal. The measurement is referenced to the
bottom of your dish so if mounted mounted fairly high up you may find that >the signal clears the top of the tree with ease.
I have a 3 storey block of flats approx 4 (terrace house) garden widths
away from my installation and I have my dish at the upstairs window level.
To block the signal the flats would have to be 18 metres taller than where
I mounted the dish. My neighbour, closer to the block of flats has his
dish mounted around 6 foot from ground level and he has no reception >problems.
On 15/04/2022 in message <jbtpm6Fa1aaU1@mid.individual.net> alan_m wrote:
What does the red blob tell you:)Â That will give the height the tree
needs to be to block the signal. The measurement is referenced to the
bottom of your dish so if mounted mounted fairly high up you may find
that the signal clears the top of the tree with ease.
I have a 3 storey block of flats approx 4 (terrace house) garden
widths away from my installation and I have my dish at the upstairs
window level. To block the signal the flats would have to be 18 metres
taller than where I mounted the dish. My neighbour, closer to the
block of flats has his dish mounted around 6 foot from ground level
and he has no reception problems.
I could play with this tool all day :-)
Placing the line on the back wall near a corner, which would be ideal, I
have a green blob that says:
Satellite: 28.2E ASTRA 2E | ASTRA 2F | ASTRA 2G
Elevation: 25.2°
Azimuth (true): 143.3°
Azimuth (magn.): 143.3°
I found the height feature - it says 24 metres for height and the tree
is slightly under the height of the chalet bungalow ridge tiles so I
will be long gone by the time it gets to 24 metres.
Fascinating! Thanks again :-)
There is often an offset between the overhead imagery overlay and the underlying map, see the example page on my site linked previously, and
this could lead to quite significant error. If when you examine the map
you find that the map of the streets doesn't exactly coincide with their position in the imagery, then you have two problems:
 1)   Which is more likely correct? I suspect most probably the map.
 2)   How much is it out, and how to compensate for it?
Further, the maths is done assuming the earth is a sphere, but it's not,
and, from memory, this introduces an error of up to half a degree at mid-latitudes for satellites that are at mid-range azimuths east or west
of the location's meridian, reducing to zero error for satellites that
are over the meridian.
With Dishpointer there is potentially a third source of error, from the
use of photographs. Right from the first, I suspected that this functionality was a gimmick of very limited real life usefulness, so
never tried to copy it. My reasoning is simply this: a photo's scale depends on the focal length of the lens, focussing, etc, which vary from camera to camera, and further the photo may not have been taken quite in
the right direction or pointing truly horizontally. If Dishpointer
don't know accurately the photo's scale, horizontality, and direction,
how do they know where to annotate markings on it?
It is - the satellites are 3° apart and alternate polarity
On 15 Apr 2022 10:29:37 GMT, "Jeff Gaines"
<jgaines_newsid@yahoo.co.uk> wrote:
There's only one neighbour with a dish, it's mounted on an extension roof
and points at the house roof so may not be too effective. There is a large >> tree which I think may be in the way which is why I want to get a rough
idea before calling an installer in.
Thanks again.
When you say "points", maybe you are referring to the dish axis, but
often the LNB is off axis, and the incoming signal is at an equal and opposite angle to the axis, i.e. over the top of the roof.
On 15/04/2022 09:51, Jeff Gaines wrote:
I am trying to see if I could have a satellite dish to serve my
Freesat box. As far as I can see from Googling I need to allow 5
degrees variation so point it at 247 degrees. Does this seem correct
for Alderholt (3 mile west of Fordingbridge, Hampshire)? At this stage
I'm just trying to see if it's feasible with trees/obstacle etc.
Will an aerial installer be able to fit me a wideband Sky dish without
signing me up to Sky?
To see if you have any obstructions
Go to https://www.dishpointer.com/
In the fist box type in your post code
In the second box select the satellite. 28.2E Astra 2E, 2F, 2G for Freesat Press the search button
You should get a map or satellite image with a green line. This line
points to the satellite.
The map or satellite image is a user selectable option
Click on the green blob at the end of the green line and drag it to you
house or location where you are going to install the dish. You can zoom
in the map or satellite image.
There is a tick box labelled "show obstacle (line of sight checker)"
This puts a moveable red blob on the green line indicating the height
you need to clear any nearby objects.
Any installer should be able to install a sky type dish for any purpose.
It's not the dish that is wideband but the LNB attached to it.
If yo already have an old Freesat box it will not support a wideband LNB
- just a universal LNB - but go for a quad universal LNB.
It's only very recently the some Freesat boxes have supported the sky wideband LNB or check your box before going down this (wideband) route.
On Fri, 15 Apr 2022 09:30:02 -0700 (PDT), R. Mark Clayton <notyalckram@gmail.com> wrote:
It is - the satellites are 3° apart and alternate polarity
Polarisation.
I'd seriously think about a unicable LNB. Just one cable and with a unicable capable receiver
Myself I'd seriously think about a unicable LNB. Just one cable and with
a unicable capable receiver it pretty much does everything any other
type can do. Get one with some legacy universal connections too if in
doubt about whether you will always have unicable capable receivers.
Brian Gregory wrote:
I'd seriously think about a unicable LNB. Just one cable and with a
unicable capable receiver
Maybe a technically elegant solution, but surely unicable receivers are
more rare than wideband ones? I suppose you could use a fancy
multiswitch at the bottom to fool a freesat receiver into thinking it's talking to a normal LNB so you do get the EPG?
AFAIK most satellites for satellite TV use both horizontal and vertical polarization to double the available bandwidth.
Where dishpointer comes in handy is getting some feel about where you
can position a dish. As I previously indicated with a 3 storey block of
flats nearby dishpointer gave me a quick confirmation that positioning a
dish anywhere on the back of my property wouldn't be a problem.
Jeff Gaines wrote:
I am trying to see if I could have a satellite dish to serve my Freesat box. As
far as I can see from Googling I need to allow 5 degrees variation
5° seems a lot.
so point it at 247 degrees. Does this seem correct for Alderholt (3 mile west
of Fordingbridge, Hampshire)
Dishpointer says 143.3°
On 15/04/2022 in message <xn0ngn6up2b8l8a003@news.individual.net> Jeff
Gaines wrote:
I am trying to see if I could have a satellite dish to serve my Freesat >>box. As far as I can see from Googling I need to allow 5 degrees variation >>so point it at 247 degrees. Does this seem correct for Alderholt (3 mile >>west of Fordingbridge, Hampshire)? At this stage I'm just trying to see if >>it's feasible with trees/obstacle etc.
Will an aerial installer be able to fit me a wideband Sky dish without >>signing me up to Sky?
Thanks for the replies :-)
I screwed the maths up, I think the answer is 153 degrees (including an >allowance of 5 for variation) as follows:
180 - 23 - 5 = 153.
I think I took the variation off twice then wrote 247 instead of 147, good >job I'm not flying to the moon!
I found:
"The most common satellites in the UK are the Astra 2 satellites at 28.2E
and Eurobird at 28.5E."
However, that's meaningless to me, the compass starts at 0 and ends at 359
or 360 depending how pedantic you want to be.
I suggested a Sky dish as with the wideband (Sky Q) version I can record 4 >channels (from memory) at a time. Doesn't happen very often that there's 4 >channels worth recording but does occasionally and as I'm starting from >scratch I might as well do it properly. If there's a non Sky version that >will do fine.
There's only one neighbour with a dish, it's mounted on an extension roof
and points at the house roof so may not be too effective. There is a large >tree which I think may be in the way which is why I want to get a rough
idea before calling an installer in.
Thanks again.
Satellites are marked in their position of degrees East and West of due
south thats 180 deg! so as near as dammit Astra 28.2 will be 180 Minus
28.2 is 151.8
Typically here, in Southern England, the satellite (Astra 2E/2F/2G at 28.2°E) is around 25° above the horizon.
https://www.dishpointer.com/
might be useful.
On 15/04/2022 17:47, R. Mark Clayton wrote:
Centuries ago the world pretty much agreed that Greenwich would be the prime Meridien. Longitudes to the east would be written nnE and to the west nnW, although these days some write -nn for east.
The satellites are geostationary over the equator so their position is given as the latitude they are over,Presumably a typo, ITYM longitude ...
For a satellite well to the east or west of your own position, you have to make allowance for the angle between you and the satellite (for 28E from 1W about five degrees,Yes, although my calculator page is no longer working (I'm working on
that, but having trouble with it), the rest of my satellite pages are
still relevant and may be helpful to the OP. The normal pages are
designed to give general information, the analysis pages show how the necessary calculations are done:
https://www.macfh.co.uk/JavaJive/AudioVisualTV/SatelliteTV/SatelliteTV.html
--
Fake news kills!
I may be contacted via the contact address given on my website: www.macfh.co.uk
On 16/04/2022 03:43, Brian Gregory wrote:
AFAIK most satellites for satellite TV use both horizontal and vertical polarization to double the available bandwidth.It's not to fully double the bandwidth. Adjacent frequencies are
transmitted with different polarisations, but the same frequency only
uses one. I'm not sure if this really allows an overlap, or whether it
is to simplify receivers.
On 15/04/2022 17:52, R. Mark Clayton wrote:
You also need the declination angle for the dish at the latitude and longitude for your location.You don't mean declination. Declination pairs with right ascension, and
is independent of location on the earth.
For a satellite overhead it is 90-latitude° and about 6-8°. So for Aldershot it is 29° - declination, which depends slightly on which satellite you are trying to receive.
I couldn't work out what these figures represent. 29° is in right
ballpark for the elevation of Astra1, we are talking about Freesat,
which is Astra 2.
Satellite dishes are normally pointed using alt-azimuth type
coordinates, although the term elevation tends to be used, rather than altitude.
Will an aerial installer be able to fit me a wideband Sky dish without >signing me up to Sky?
On 17/04/2022 14:28, Jeff Gaines wrote:
I'd like the leads to terminate in a dual F Type outlet so I can use
flying leads. Sky installers would rather just run the leads through the >>wall. Is a dual F Type outlet box workable?
Yes.
Bill
I'd like the leads to terminate in a dual F Type outlet so I can use
flying leads. Sky installers would rather just run the leads through the wall. Is a dual F Type outlet box workable?
On Saturday, 16 April 2022 at 10:44:16 UTC+1, David Woolley wrote:
On 16/04/2022 03:43, Brian Gregory wrote:
AFAIK most satellites for satellite TV use both horizontal and verticalIt's not to fully double the bandwidth. Adjacent frequencies are
polarization to double the available bandwidth.
transmitted with different polarisations, but the same frequency only
uses one. I'm not sure if this really allows an overlap, or whether it
is to simplify receivers.
Successive transponders use alternate polarisation (H & V)
For the adjacent satellites 3 degrees either side the polarisation is reversed (V & H)
This reduces adjacent channel interference on the same satellite and co-channel interference on adjacent satellites.
I presume the frequency figures are nominal and that 11264H and 11264V
are actually on slightly different frequencies, but is it enough to
avoid H versus V interference,
When a dish is installed, is one the adjustments the rotation of the
dish so H and V on the dish are accurately aligned with the H and V
signals (ie adjust for max H and min V on a known H-polarised frequency).
What about the frequencies where there is a service on both H and V. For example (for Astra 28.x): 11264H and 11264V, 11306H and 11306V, 11344H
and 11344V, 11386H and 11386V, 11426H and 11426V. I presume the
frequency figures are nominal and that 11264H and 11264V are actually on slightly different frequencies, but is it enough to avoid H versus V interference, when everywhere else in the spectrum there is a gap of at
least 10 MHz between an H and a V.
When a dish is installed, is one the adjustments the rotation of the
dish so H and V on the dish are accurately aligned with the H and V
signals (ie adjust for max H and min V on a known H-polarised frequency).
On 17/04/2022 16:09, NY wrote:
I presume the frequency figures are nominal and that 11264H and 11264V
are actually on slightly different frequencies, but is it enough to
avoid H versus V interference,
The signals are several MHz wide. You can't fit in two multiplexes
without most of them overlapping each other.
On 17/04/2022 16:09, NY wrote:
I presume the frequency figures are nominal and that 11264H and 11264VThe signals are several MHz wide. You can't fit in two multiplexes
are actually on slightly different frequencies, but is it enough to
avoid H versus V interference,
without most of them overlapping each other.
On Sunday, 17 April 2022 at 19:14:55 UTC+1, David Woolley wrote:adjacent channel will be nulled out.
On 17/04/2022 16:09, NY wrote:Correct - Transponders with the same polarisation do not overlap, but the transponders with the other polarisation sit in between. As long as your LNB is accurately set up then the polarisation will mean that on frequency the polarisation of the
I presume the frequency figures are nominal and that 11264H and 11264V are actually on slightly different frequencies, but is it enough to avoid H versus V interference,The signals are several MHz wide. You can't fit in two multiplexes
without most of them overlapping each other.
Just double checked - for $ky on 28E they used H & V on the same frequency on a lot of transponders - you LNB skew will need to be very accurate in this case.
On 16/04/2022 14:16, tony sayer wrote:
Satellites are marked in their position of degrees East and West of due
south thats 180 deg! so as near as dammit Astra 28.2 will be 180 Minus
28.2 is 151.8
No they are not. They are labelled by the longitude that they are over
at the equator. In the extreme case, of someone on the equator, their >azimuth is 90° or 270°. If you are at longitude 0, on the equator, the
angle to them below the vertical will still be larger than their station >position, because it is measured from the Earth's surface, whereas the >satellite position is relative to the centre of the Earth.
At the exact poles, the azimuth will be the nominal position, but due
South will be indeterminate, so you will need to use the prime meridian
as the reference. (More of a problem is that the elevation will be
negative, by about 8.5°.)
Elsewhere, on the prime meridian, azimuth, for most practical targets is >likely to be larger than the nominal position, although, for 90° and
270° positions it will be slightly smaller, because azimuths 90° and
270° are along a parallel of latitude but the satellites are over a more >southerly one (northern hemisphere).
For the gory details of the maths, including corrections for the >non-spherical Earth, see ><https://www.ngs.noaa.gov/CORS/Articles/SolerEisemannJSE.pdf>. The
parameter used to specify positions is what the article calls
sub-satellite point longitude.
| Sysop: | Keyop |
|---|---|
| Location: | Huddersfield, West Yorkshire, UK |
| Users: | 297 |
| Nodes: | 16 (2 / 14) |
| Uptime: | 06:35:47 |
| Calls: | 6,666 |
| Files: | 12,213 |
| Messages: | 5,336,028 |