Ground Control

Jordan HodgeJordan LyfordWilson Schreiber

2

Contents

Background Problem Statement Solution Software

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Background

VTC developing CubeSat, transmits data Continuing where previous groups have left off

Have to follow CubeSat to receive data

Existing 3-meter parabolic dish antenna

Low orbit satellite revolves around earth in minutes, seen for short time per orbit

Existing solutions EGIS Bi-axial antenna positioning system

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EGIS Rotor and Control

Equipment-Gesellschaft für Internationale Elektronik Systeme

Cost: Software $400 Data Interface $1,100 Hardware $2,700 (EL-40°, AZ-180°) Extension $2,200 (EL-90°, AZ-360°) Rotor Hardware Mount $400 Satellite Dish Mount $400

Total $7,200

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SatPC32

A free software available online for tracking satellites. Updates on screen and controls rotor to point to position satellite

Uses orbit of satellite and observer position

Many types of rotors to select for output

Uses Serial port or Parallel port on PC

SatPC32

Screen Shot of SatPC32 in use

WinListen predicts path

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Problem

Track a low orbit satellite such as a CubeSat from horizon to horizon is as little as 30 seconds180°/30 seconds=6°/sec

Move a 3 meter satellite dish 360° Azimuth (left/right) 90° Elevation (up/down)

Interface to PC running SatPC32

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Solution

Gears and motors, motor controllers Freescale Coldfire 32-bit

Microcontroller Serial interface with SatPC32 using

EGIS controls and a serial port Magnetic Encoders measure position

of dish Use/Modify existing designs for

elevation and azimuth control

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System Diagram

Micro-controller

EL - Motor

ControllerAZ -

Motor Controlle

r

Limit Switches

RS232

SatPC32

PositionEncoders

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Mechanical Concepts

Azimuth A left to right angle

measurement from a fixed point (north in navigation)

Worm Gears Speed (Gear Ratio) Torque Modify existing designs

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Power Distribution

Position Encoders

AC

Motor Controlle

r

Motor Controlle

r

12Vdc10Amp

FUSE

5Vdcregulat

or

Micro-controller

A

E

Circuit Protectio

n

12Vdc10Amp

FUSE

PC Running SatPC32

Limit Switc

h

Limit Switc

h

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Programming

Read new position from serial port Stores values when they come in

Read actual position from encoders Measure periodically

Decide where to turn, how fast

Always checking limit switches If ever activated, stop motors

Controller(Set

Outputs)

New Serial

?

Check Encoder

s?

ReadSerial

Read Encoders

Questions?