When setting up a satellite dish, it is quite helpful to know the actual solar time (not mean solar time) and hence the direction to the geostationary satellite. Twice a year, the sun is in the same direction as the satellite and you can watch if any obstacles will cast a shadow to the intended antenna location. For other dates, you will have to apply some vertical correction.
Between the autumn exact match and spring exact match the sun is below the geostationary satellite and you can be sure that no obstacles are between your location and the satellite. Of course this might be an overkill if checked in the middle of the winter.
By using solar time, you get a much more accurate azimuth direction compared to some ordinary magnetic compass.
When actually pointing a big dish with a beamwidth less than a degree, it helps a lot, if you know the azimuth accurately (e.g. by looking at the shadow cast by the microwave head on the dish), then you only have to find the correct altitude.
For equatorial or polar mounts, I have never needed to know the time. Geosynchronous satellites do not move (much) from their position in the sky. It's in the same place, no matter what the time. However, if I were tracking a non-geosynchronous bird, accurate time is vital.
I live in a forest, where DBS satellite reception is dependent on finding a hole in the tree canopy. Twice a year, we have the "solar outage" where the sun appears behind the satellite belt which obliterates reception for a few minutes. Here's photos of 101 longitude for DirecTV at my house: Areas where there is sunlight on my roof are suitable locations for the dish antenna. I no longer use DirecTV, but when I did, I had to move the dish every year as the trees grew and the hole moved.
For other times, there are various "satellite finder" programs. I use several on my Android phone including an "augmented reality" program that overlays the satellite belt on top of the camera image. It's not very accurate but offers a good clue if reception is possible.
I *NEVER* use a magnetic compass. It's too inaccurate. I use an ordinary road map and a plywood map board. I pound a nail at my location on the map into the map board. I then find a distant reference point that I can see on the map. I align its map location to the distant reference point and pound in another nail. Now, the map is properly aligned. No compass required. When pre-setting the dish azimuth, I make it parallel to the azimuth line on the map.
Yes, sorta. For polar mounts, such as common Ka/Ku band DBS dishes, I simply calculate the required elevation, preset the elevation and tilt on the dish, and spin it around until I hear the satellite. Not a big deal and requiring only an inline signal level meter. Also, the J-pipe mount has to be perfectly vertical for this to work.
It's not quite so simple with an equatorial mount which is designed to track the satellite belt across the sky. For these, the satellites appear in a tilted arc across the sky. Setting up such a dish is a bit tricky, but has the advantage of being able to be properly pre-aligned for the entire visible satellite belt.
I recently orchestrated rearranging some dishes at a local radio station: The 3 meter dish is a polar mount and was quite easy to aim. The 4 meter dish was an equatorial and proved to be a big problem. Finding the correct azimuth was easy, but since it was over the ocean, there was no easy aiming point. So, I planted a bright orange garbage bag where it crossed the coastal roadway and attempted a bore sight alignment: Eventually, I got it right after discovering a 1 degree bore sight error, which produced a 2 degree elevation error. My most important aiming tools were a 0.1 degree resolution digital bubble level and a satellite signal meter to identify which satellite the dish was hearing.
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Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
On a sunny day (Sun, 19 Jan 2014 00:52:53 +0200) it happened snipped-for-privacy@downunder.com wrote in :
I usually work the other way around, use sat calculator to get elevation for the sat you want to receive, and the longitude and latitude you are. Tune receiver to transponder and PID for the program you want on that sat. Set elevation (scale on disk mount), and sweep the dish by hand from east to west or vice versa, Monitor signal level, you will find several sats.
If you point the right sat you get a picture, and you _know_ the exact angle. Monitor signal level for fine adjustment of azimuth and elevation.
Magnetic compass or whatever only helps slightly if at all, sun is normally (!) in the south from where I am (in the north). I sort of guess it will be in the north from down under?
xdipo:
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All you need is GPS or google maps for your location, and for example kingofsat.net for the sat location and tuning parameters. Satellite is easy, a LOT easier than getting good DVB-T reception here... Seems to me DVB-T (terrestrial) is a big disaster.
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