Geosynchronous Satellite Look Angle Calculator for LabVIEW

[ve3wtj]

Description

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1. Overview

This VI will calculate the azimuth and elevation for pointing a satellite dish at a geosynchronous satellite.

2. Description

A geostationary orbit, geostationary Earth orbit or geosynchronous equatorial orbit (GEO) is a circular orbit 35,786 kilometres (22,236 mi) above the Earth's equator and following the direction of the Earth's rotation. An object in such an orbit has an orbital period equal to the Earth's rotational period (one sidereal day) and thus appears motionless, at a fixed position in the sky, to ground observers.

Communications satellites and weather satellites are often placed in geostationary orbits, so that the satellite antennas (located on Earth) that communicate with them do not have to rotate to track them, but can be pointed permanently at the position in the sky where the satellites are located.

Latitude is North - South (up and down). Longitude is West - East (sideways). Latitude is zero on the equator and positive in the northern hemisphere and negative in the southern hemisphere. Longitude is zero on the prime meridian - home of Greenwich Mean Time and is positive to the east, across Europe and Asia. Longitude is negative to the west, across the Atlantic and the Americas. Read about the history of latitude and longitude. Look here for my animated views of the Planet Earth.

Elevation refers to the angle between the beam pointing direction, directly towards the satellite, and the local horizontal plane. It is the up-down angle.

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 mount bracket and swing the whole dish all the way around in a 360 deg circle.

3. Requirements

• NI LabVIEW Base Development System 2012 or compatible.

4. Steps to Implement or Execute Code

1. Download and unzip the compressed files
2. Open “Satellite Look Angle Calculator LabVIEW 2012 NIVerified.lvproj” and the VI “Satellite Look Angle Calculator Main.vi”
3. Write the coordinates of your location in the Station control. An altitude of mean sea level is assumed.
4. Indicate the Longitude of the Geosynchronous Satellite you want to point your antenna towards. Geosynchronous altitude and latitude (0) are assumed.
5. Run the VI.

5. Additional Information or References

• Satellite Communication Principles; Abdullah Al-Ahmadi; College of Engineering; Majmaah University: https://faculty.mu.edu.sa/public/uploads/1393177378.6803Satellite%20Introduction.pdf 
• Satellites Latitude and Longitude: http://www.satsig.net/maps/lat-long-finder.htm
• Express Math Functions: https://www.ni.com/docs/en-US/bundle/labview-api-ref/page/menus/categories/express/arithmetic/expres...

**The code for this example has been edited to meet the new Community Example Style Guidelines.**

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