Look Angle Calculators

These set of programs calculate look angles from one set of coordinates to the next. This is extremely useful for automatic antenna tracking of moving transmitters with telemetry.

These take longitude and latitude in decimal degrees and altitude in meters. They return azmuth and elevation in degrees, and range in meters.

There are currently two implementations useing different geodetic systems, namely the WGS 84, and a simplistic spherical system. If you're using GPS data, use the wgs84 programs (GPS uses the WGS 84 geodetic system).

Notes on using these for antenna pointing

If you're using this for antenna pointing you'll probably want to be careful about some situations you might run into.

Some of these include:

These will indicate an azimuth of 90 when the station being observed is directly overhead. If you're coming from some other azimuth and the station is passing directly over head you might not want to try and go through the entire azimuth to 90 and then down whatever azimuth it leaves that for. The way I'd solve this is to not care about the azimuth results if the station gets close to 90.

If you're really close to the observed station your antenna pointer will probably be bouncing around in its readings. The way I'd solve this is to recognize when the range is below some value and average the readings. In this way we're not moving around all of the time but we're still trying to point in the correct direction.

Really the way to solve these situations is application specific so enjoy!

KG4SGP - Jim