|
Satellite dish positioning
Has anyone tried using a satellite dish low on the northeast side of a
flat? Looking at some on-line alignment info, it looks as though for the Freesat satellite the dish needs to point almost exactly parallel to surface of the wall, which might attenuate the signal pretty badly depending on things like possible refraction. Do any of the satellites further east than the Astra 2 A-B-D also carry Freesat signals? If so, the dish could be pointed further from the wall. The point of this idea is to keep the dish off the roof and out of the way of roof repairers, aerial installers, and the like. -- Windmill, Use t m i l l @ O n e t e l . c o m |
Satellite dish positioning
|
Satellite dish positioning
On 25/10/2010 14:36, David Hansen wrote:
On Mon, 25 Oct 2010 10:03:20 GMT someone who may be lid (Windmill) wrote this:- Looking at some on-line alignment info, it looks as though for the Freesat satellite the dish needs to point almost exactly parallel to surface of the wall, which might attenuate the signal pretty badly depending on things like possible refraction. Shouldn't do so. Many buildings have satellite dishes in this position on the walls. My dish was about 6' above the ground looking straight along a wall for a long time. It worked fine until a neighbours tree grew too high (took about 5 years) |
Satellite dish positioning
Terry Casey writes:
Looking at some on-line alignment info, it looks as though for the Freesat satellite the dish needs to point almost exactly parallel to surface of the wall, which might attenuate the signal pretty badly depending on things like possible refraction. So long as it is parallel to or angled slightly away from the wall, you shouldn't have a problem - the beam width is very narrow. A guesstimate based on eyeballing a Google map suggest that the wall is in a plane about 40 degrees counterclockwise from due south, i.e. about 140 degrees. The satellite data says it is at 143 degrees, which would put it 3 degrees behind solid sandstone :-( However I belatedly thought of looking for other dishes, and can see one. So maybe...... -- Windmill, Use t m i l l @ O n e t e l . c o m |
Satellite dish positioning
David Hansen writes:
Shouldn't do so. Many buildings have satellite dishes in this position on the walls. The problem is that the satellite might be out of view, just barely, _behind_ the side of the wall. I asked the City if they had any maps showing building orientation, but seemingly not. -- Windmill, Use t m i l l @ O n e t e l . c o m |
Satellite dish positioning
In article ,
Windmill wrote: I asked the City if they had any maps showing building orientation, but seemingly not. Have you tried one of the sites that superimposes the direction to satellites on top of Google Maps? E.g. http://www.dishpointer.com -- Richard |
Satellite dish positioning
On Wed, 27 Oct 2010 20:49:26 GMT, Windmill wrote:
The problem is that the satellite might be out of view, just barely, _behind_ the side of the wall. At this time of year the sun is roughly in the same position as the constellation of satellites for Freesat/Sky etc about 0920 GMT (1020 BST)(*). Anywhere that is clearly sunlit at that time should be able to see the satellites. Dish mounts do let you peek a dish around a corner. (*) Fairly sure I've got the time right, if I haven't some one will no doubt correct me. -- Cheers Dave. |
Satellite dish positioning
In article o.uk,
Dave Liquorice wrote: At this time of year the sun is roughly in the same position as the constellation of satellites for Freesat/Sky etc about 0920 GMT (1020 BST) This will vary across the country (and of course with the date), so don't rely on it if it's marginal. -- Richard |
Satellite dish positioning
On Thu, 28 Oct 2010 09:25:47 +0000 (UTC), Richard Tobin wrote:
At this time of year the sun is roughly in the same position as the constellation of satellites for Freesat/Sky etc about 0920 GMT (1020 BST) This will vary across the country (and of course with the date), so don't rely on it if it's marginal. Pay attention to the qualifiers "at this time of year" and "about" in relation to the time and "clearly" in relation to the illumination. The bearing will be correct no matter the time of year but I agree the elevation will change quite a bit between the equinoxes ("at this time of year") when the sun is more or less in the same place and mid winter/summer when it will be below (winter) or above (summer) the position. I got the time wrong. For here with a longitude of 2.5W it's more like 1035 BST (I looked at the shadow on our dish...). If I've worked it out right 1020 would be for a location with a longitude about 1.5E. -- Cheers Dave. |
Satellite dish positioning
In article , spam-no-
lid says... Terry Casey writes: Looking at some on-line alignment info, it looks as though for the Freesat satellite the dish needs to point almost exactly parallel to surface of the wall, which might attenuate the signal pretty badly depending on things like possible refraction. So long as it is parallel to or angled slightly away from the wall, you shouldn't have a problem - the beam width is very narrow. A guesstimate based on eyeballing a Google map suggest that the wall is in a plane about 40 degrees counterclockwise from due south, i.e. about 140 degrees. The satellite data says it is at 143 degrees, which would put it 3 degrees behind solid sandstone :-( The satellite data will be WRT true north but, if the map data originates from the Ordnance Survey, it will be WRT grid north, so you may not be comparing like with like ... .... and you did say 'about 40 degrees'! How accurate is 'about'? After all, a 3 degree discrepancy could mean the difference between success and disaster ...! You may find this useful: http://www.macfh.co.uk/JavaJive/Audi...SatelliteCalcu lator.php or http://tinyurl.com/3afzpuw This uses Google maps but, if you enter your OS grid reference or PostCode, you also have the option of using OS maps. If the position is not quite accurate, you can drag the dish location around the map. At maximum zoom, the OS shows the outlines of buildings, which might be particularly useful to you ...! -- Terry |
Satellite dish positioning
In article o.uk,
Dave Liquorice wrote: The bearing will be correct no matter the time of year That's not true, unless you read the time from a sundial rather than a mechanical clock. The eccentricity of the earth's orbit and the fact that the sun does not stay exactly within the plane of the equator mean that sun time varies from human time by up to 16 minutes, which corresponds to an error in the bearing of up to 4 degrees. See http://www.sundials.co.uk/equation.htm -- Richard |
Satellite dish positioning
(Richard Tobin) writes:
Have you tried one of the sites that superimposes the direction to satellites on top of Google Maps? E.g. http://www.dishpointer.com I'll try that. The map I was using showed a line but not its compass heading, which by inaccurate eyeball was approx. 140 degrees. -- Windmill, Use m a i l @ r m i l l . a d s l 2 4 . c o . u k |
Satellite dish positioning
(Richard Tobin) writes:
Have you tried one of the sites that superimposes the direction to satellites on top of Google Maps? E.g. http://www.dishpointer.com Tried that one; it's better than the one I used before. It shows that the line-of-sight to the satellite is about 0.1 degree more than the angle of the rear, NE side, of the building (just guessing, it barely converges with the rear of the building over a distance of about six stairs spacing; maybe 500 feet). Amazing coincidence. So if the dish is fixed a few feet from the wall it _should_ work. Thanks for the pointer. -- Windmill, Use m a i l @ r m i l l . a d s l 2 4 . c o . u k |
Satellite dish positioning
"Dave Liquorice" writes:
On Wed, 27 Oct 2010 20:49:26 GMT, Windmill wrote: The problem is that the satellite might be out of view, just barely, _behind_ the side of the wall. At this time of year the sun is roughly in the same position as the constellation of satellites for Freesat/Sky etc about 0920 GMT (1020 BST)(*). Anywhere that is clearly sunlit at that time should be able to see the satellites. Dish mounts do let you peek a dish around a corner. It's a very very close thing, but there is one (only one) other dish along the whole length of the street i.e. in about 100 rear-facing flats. So either possible, or the dish owner has been disappointed. Might have to build a contraption to space the dish away from the wall. -- Windmill, Use m a i l @ r m i l l . a d s l 2 4 . c o . u k |
Satellite dish positioning
(Richard Tobin) writes:
Have you tried one of the sites that superimposes the direction to satellites on top of Google Maps? E.g. http://www.dishpointer.com Just had another look, to reconfirm that a dish will probably work. Amusingly it tells me that my nearest satellite installer is in Mississauga, Canada ! -- Windmill, Use t m i l l @ O n e t e l . c o m |
Satellite dish positioning
|
Satellite dish positioning
In article ,
Sam Wilson wrote: This is probably a bad idea since I know almost nothing about how radio waves propagate at sat-TV frequencies, but is there any chance of getting a reflection of something at the other side or at the end of the block? I don't think that works. For expert advice try uk.tech.digital-tv. -- Richard |
Satellite dish positioning
In article -
september.org, Sam Wilson scribeth thus In article , lid (Windmill) wrote: "Dave Liquorice" writes: On Wed, 27 Oct 2010 20:49:26 GMT, Windmill wrote: The problem is that the satellite might be out of view, just barely, _behind_ the side of the wall. At this time of year the sun is roughly in the same position as the constellation of satellites for Freesat/Sky etc about 0920 GMT (1020 BST)(*). Anywhere that is clearly sunlit at that time should be able to see the satellites. Dish mounts do let you peek a dish around a corner. It's a very very close thing, but there is one (only one) other dish along the whole length of the street i.e. in about 100 rear-facing flats. So either possible, or the dish owner has been disappointed. Might have to build a contraption to space the dish away from the wall. This is probably a bad idea since I know almost nothing about how radio waves propagate at sat-TV frequencies, but is there any chance of getting a reflection of something at the other side or at the end of the block? I also assume you're not on the ground floor since you would already have thought about mounting the dish on the ground away from the wall, right? Sam Just wouldn't be strong enough to do that, let along at being just the right angle etc!... -- Tony Sayer |
Satellite dish positioning
Sam Wilson writes:
This is probably a bad idea since I know almost nothing about how radio waves propagate at sat-TV frequencies, Pretty much straight line, I think. Otherwise the airport surveillance radars which show ATC/S where on the taxiways planes are on a foggy day or after dark wouldn't be much use. (I think that's called X band , or some such, running at frequencies vaguely similar to satellite Ku band.) but is there any chance of getting a reflection of something at the other side or at the end of the block? Quite probably, but AIUI the direct signal is already very weak, having travelled 22,400 miles. I'm sure one could use a reflection if one used a 30 foot dish, say, but...... I also assume you're not on the ground floor since you would already have thought about mounting the dish on the ground away from the wall, right? One floor up. I'm pondering where best to put the dish so the protruding [ shaped attachment to the neighbouring drainpipe doesn't get in the way. But I don't know the elevation above our horizontal of synchronous satellites at our latitude. About 30 degrees, I'm guessing. Obviously I will learn this along the way! -- Windmill, Use t m i l l @ O n e t e l . c o m |
Satellite dish positioning
In message , Windmill
writes Sam Wilson writes: This is probably a bad idea since I know almost nothing about how radio waves propagate at sat-TV frequencies, Pretty much straight line, I think. Otherwise the airport surveillance radars which show ATC/S where on the taxiways planes are on a foggy day or after dark wouldn't be much use. (I think that's called X band , or some such, running at frequencies vaguely similar to satellite Ku band.) but is there any chance of getting a reflection of something at the other side or at the end of the block? Quite probably, but AIUI the direct signal is already very weak, having travelled 22,400 miles. I'm sure one could use a reflection if one used a 30 foot dish, say, but...... I also assume you're not on the ground floor since you would already have thought about mounting the dish on the ground away from the wall, right? One floor up. I'm pondering where best to put the dish so the protruding [ shaped attachment to the neighbouring drainpipe doesn't get in the way. But I don't know the elevation above our horizontal of synchronous satellites at our latitude. About 30 degrees, I'm guessing. Obviously I will learn this along the way! In the UK, the Astra 2 A-B-D - Eurobird 1 bunch (at appx 28.2) are at an elevation of around 25 degrees, depending on your latitude. It's surprising how low that is! BTW, I'm also in the process of getting a satellite system going, and I find that this is definitely one of the more useful sites for programme and channel information: http://en.kingofsat.net/freqs.php?&p...ordre=freq&fil tre=Clear -- Ian |
Satellite dish positioning
tony sayer writes:
[......] but is there any chance of getting a reflection of something at the other side or at the end of the block? Just wouldn't be strong enough to do that, let along at being just the right angle etc!... ISTR that reflection also rotates the plane of polarisation by 90 deg. Which would confuse these LNB things, because apparently different channels are transmitted with different polarisations. I read that this is the reason why you need LNBs with two or more outputs if you want to have two or more TVs able to receive different channels at the same time - a single LNB output can be switched by a single sat receiver to receive differently polarised signals, but it can't be set for both vertical and horizontal polarisation at the same time. Or that's my understanding. -- Windmill, Use m a i l @ r m i l l . a d s l 2 4 . c o . u k |
Satellite dish positioning
|
Satellite dish positioning
On Fri, 29 Oct 2010 19:30:58 GMT, Windmill wrote:
But I don't know the elevation above our horizontal of synchronous satellites at our latitude. About 30 degrees, I'm guessing. Close enough but remember if you are talking about a Sky "mini dish" they are offset dishes. This means that the face of the dish is more vertical than one would expect. -- Cheers Dave. |
Satellite dish positioning
On Mon, 01 Nov 2010 15:11:54 +0000 (GMT) someone who may be "Dave
Liquorice" wrote this:- Close enough but remember if you are talking about a Sky "mini dish" they are offset dishes. This means that the face of the dish is more vertical than one would expect. In southern Scotland the dish of offset dishes is usually pretty much horizontal. In the north the dish can appear to point downwards. -- David Hansen, Edinburgh I will *always* explain revoked encryption keys, unless RIP prevents me http://www.opsi.gov.uk/acts/acts2000...#pt3-pb3-l1g54 |
Satellite dish positioning
In message , David Hansen
writes On Mon, 01 Nov 2010 15:11:54 +0000 (GMT) someone who may be "Dave Liquorice" wrote this:- Close enough but remember if you are talking about a Sky "mini dish" they are offset dishes. This means that the face of the dish is more vertical than one would expect. In southern Scotland the dish of offset dishes is usually pretty much horizontal. I think you meant 'vertical'. In the north the dish can appear to point downwards. From Gretna Green to Lerwick (which is a long way east), the difference is about 3 degrees (for an elevation of around 17 to 21 degrees). From Gretna Green to Kirkwall, it's a bit less. http://www.dishpointer.com/ -- Ian |
Satellite dish positioning
|
Satellite dish positioning
Ian Jackson writes:
Don't forget that the polarization of the signals is 'skewed', so they don't arrive exactly horizontal and vertical. The LNB will need to mounted so that it is also skewed (rotated in its mounting clamp). In the case of the 28 degree east satellites, the skew angle is around 13 degrees clockwise, looking towards the dish. Useful info; thanks. -- Windmill, Use t m i l l @ O n e t e l . c o m |
| All times are GMT +1. The time now is 11:45 PM. |
Powered by vBulletin® Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004 - 2014 DIYbanter