What’s the difference? What to choose. By Jordan Lyford Group: Ground Station.
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Transcript of What’s the difference? What to choose. By Jordan Lyford Group: Ground Station.
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?