Azimuth/Elevation vs. Elevation/Azimuth

What’s the difference?What to choose.

By Jordan Lyford Group: Ground Station

What is Azimuth and Elevation

Azimuth• A compass bearing• True North is Zero• Spins around the

vertical axis

Elevation (Altitude)• Angle between the flat plane and the object

in the sky (satellite).

Issues with tracking Satellites

Satellites sometimes have unusual orbit characteristics. • Some orbit the earth around the equator• Some orbit around the earth’s poles• Some just hang out

They can drift from the original orbit path around the earth.

Know what you’re going to track Single Axis

• Needs only an Azimuth motion (elevation never changes)• Also called a Polar orbit

Dual Axis**• Both Elevation and Azimuth need motion to track the

satellite• Needed when Satellite has an unusual orbit

Stationary Dish• Tracking a satellite that is stationary (Direct TV or Hughes

Net)• The Satellite is Geostationary

Azimuth and Elevation Mounting Considerations

Altitude-Azimuth Mount• Very basic and simple to build• Is the cheapest setup

-- However takes a much moresophisticated motorized

control system.

-- When the elevation hits 90 degrees, the motors go ??????

Solution To the Zennith Problem

A Fork Mount:• Same simple left-right/up/down characteristics

• Allows the dish to go over backwards if it needs to.

Azimuth and Elevation Mounting Considerations

Equatorial Mount• The movement of the Azimuth (here the Declination Axis)makes an arc in the sky.

• The Elevation (a) is set parallel to the earths axis of rotation.

This system is much more accurate than the Fork and needs a much less complicated control system.

So What’s the Best Choice Knowing the Satellite path ultimately

determines what setup is best.

• If the Satellite orbit is not a polar orbit,then the Equatorial Mount might be the best choice.

What’s the Best Choice If there is a polar orbit, or strange

orbit all together:

The Dish with the Fork configuration may bethe best choice.

Variations

Fork Mount Equatorial/Fork Mount

Most Popular Form of Large Scale Tracking Systems: Fork Mount

Deep Space Tracking Lab Dishes (Australia, Brazil)

Personal Opinion for our Project

It depends on the Satellite Path

• The Fork mount configuration if we want versatillity

• The Equatorial configuration if the satellite path is normal to the earths rotation and surface.

Questions and Comments?