How to get elevation ?

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jeremy
Posts: 17
Joined: April 8th, 2011, 10:38 am

How to get elevation ?

Postby jeremy » July 21st, 2011, 1:44 pm

Hi,

I would like to know how can I compute the Azimuth/Elevation of an aircraft when I know its Latitude/Longitude/Altitude values ?

Thanks.

DaveReid
Posts: 5911
Joined: July 2nd, 2005, 8:25 am
Location: Reading, Berks
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Re: How to get elevation ?

Postby DaveReid » July 21st, 2011, 3:27 pm

jeremy wrote:I would like to know how can I compute the Azimuth/Elevation of an aircraft when I know its Latitude/Longitude/Altitude values ?

At the ranges we can pick up aircraft transmitting Mode S, you can assume a flat earth without losing much in terms of accuracy.

Start by calculating how far north or south of you an aircraft is by the difference in the respective latitudes (1 minute = 1 nm). The east/west distance in nm is similarly the difference in longitudes in minutes multiplied by the cosine of the latitude.

Then it's simple trigonometry to calculate the relative bearing (azimuth) of the target, and the distance (which you need for the next step).

For the elevation, again ignoring the curvature of the earth, it's simply the arctan of the altitude of the target divided by the distance from you to it.

If you really need precision results, then you will have to use spherical trigonometry, but that's your call.

jeremy
Posts: 17
Joined: April 8th, 2011, 10:38 am

Re: How to get elevation ?

Postby jeremy » July 26th, 2011, 3:35 pm

Thank you for these explanations.
I need acuracy so I will check the spherical trigonometry :)


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