How To Set Azimuth And Elevation

Explanation of Azimuth and Elevation

Azimuth and elevation refer to the satellite TV dish pointing angles.

diagram explaining elevation angle

Elevation

Elevation refers to the angle betwixt the beam pointing direction, directly towards the satellite, and the local horizontal plane. It is the upwards-downward angle.

When your dish is pointed low down nigh the horizon the elevation angle is only a few degrees. At low elevation angles, below v deg at C band and 10 deg at Ku band, the path through the atmosphere is longer and the signals are degraded past rain attenuation and rain thermal noise. Scintillation also occurs, especially in hot humid conditions. This causes increases and decreases in the betoken level every several seconds for many hours, like the twinkling of a star.

When your dish is pointed almost straight upwardly the peak angle is nearly 90 degrees. Sites near the equator may require y'all to betoken to well-nigh 90 deg elevation angle when the longitude of the satellite is similar to the longitude of the site location. In high top cases sentry out for the possibility of rain h2o collecting in the dish.

It is easy to prepare the elevation bending accurately, using:

(a) a scale marked on the mount bracket. This is almost essential for 'kickoff antennas' where the feed/LNB is supported by a feed support arm at the bottom. Make certain the pole mount is vertical using a bubble level or weighted string in two positions at right angles effectually the pole. The get-go angle may be documented in the installation instructions. If you have an kickoff dish and accept the front confront of the dish vertical, then the beam elevation angle is the same as the documented offset bending.

(b) using an inclinometer. These typically have a chimera level and a rotary scale marked in degrees. Think about low angles (near zero), the 45 deg half style angle and loftier angles (towards 90 deg) and make sure that your scale readings make sense. You may need to add or subtract ninety or 180 deg and fifty-fifty to read the scale backwards. If you are using an axi-symmetric dish the back of the dish is commonly at right angles to the beam and at that place may be some suitable flat role where you can apply the inclinometer.

(c) If you don't have an inclinometer then make an inclinometer using a slice of menu, a length of cotton and a small weight (modest metal nut, for example). Make a hole near one border and insert the thread and so that the weight dangles beyond the card. Draw on the carte du jour the exact superlative bending required using a school compass or two lines at right angles and trigonometry (tan function suggested) at Start, Programmes, Accessories, Calculator, Scientific mode. This kind of home made device can be far more accurate that a small inclinometer sold in a DIY store. For big dishes a long plumb line can be used and sideways measurements used with tan tables to determine angles accurately.

diagran explaining azimuth angle

Azimuth

Azimuth refers to the rotation of the whole antenna around a vertical axis. It is the side to side angle. Typically you loosen the main mountain bracket and swing the whole dish all the way around in a 360 deg circle.

By definition Due north is 0 deg, East is 90 deg, South is 180 deg and Westward is 270 deg. North can also be called 360 deg.

Note that you discover a satellite by pre-setting the pinnacle accurately so swinging the whole antenna boldly in azimuth till the signal locks upward - and then an approximate azimuth angle is normally sufficient.

The dish pointing calculator gives the required azimuth bending both relative to true north and relative to magnetic compass north.

When using a magnetic compass keep away from metal structures. This is obviously a problem in many cases both with the antenna steelwork and building structures. If, for example, you lot accept a close angle clearance problem with say an next wall so yous may need to walk some distance away and sight towards the satellite from say 50 yards back. Large scale precision maps / plans tin exist useful in accurately defining angles. Besides consider long range views of say church towers that might provide an authentic azimuth reference.

If you are in the northern hemisphere then call back that the sun rises in the east, reaches its highest angle at due south and sets in the west.
If you are in the southern hemisphere then recall that the lord's day rises in the east, reaches its highest angle at due north and sets in the westward.

If you are away from the equator and it is a sunny day you tin approximately determine s simply by considering where the sun is and the general fourth dimension of day. To summate sun or moon angles at whatsoever time go here:

aa.usno.navy.mil/data/docs/AltAz.php (bad link ?)

or sun merely go hither:

https://www.esrl.noaa.gov/gmd/grad/solcalc/azel.html

Sun or moon altitude is the same thing as elevation angle.

If you are near the equator annotation where the sun rose this morning - that is approximately east.

The north pole star gives a good fix if you lot are in the northern hemisphere and not likewise shut to the equator. Here is how to find true north using the pole star.

Some GPS receivers show a view of the sky with the lord's day and moon marked. Line up with 1 of these and you have a good bearings. Also with GPS you lot can walk a while in a directly line and determine the azimuth begetting angle of that line.

Page 24 Oct 2004, amended 25 Feb 2022.

Whatsoever problems, please email me, eric@satsig.internet