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NARSS Cube Satellite Project
Prepared by:
Checked by:
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Obour Academy
Team: A5
11/8/2016
OBC
On Board Computer
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Record of revision
ISS/REV Date Modifications Created/Modified by
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Content
RECORD OF REVISSIONS…………………………………………………………………………………………………………………………………………………………
FOREWORD ……………………………………………………………………………………………………………………………………………………………………………
INTRODUCTION ……………………………………………………………………………………………………………………………………………………………………..
1 REFERENCES ...............................................................................................................................................................................
2 PROJECT OBJECTIVES ……………………………………………………………………………………………………….
3 RESEARCH PRELIMINARY......................................................................................................................................................
4 ABBREIATED TERMS …………………………………………………………………………………………………………
5 WHAT HAVE THE STUDENTS LEARNT IN THIS PROJECT? ………………………………………………………………………..
6 ON-BOARD COMPUTER CODE [SPACE SEGMENT] …………………………………………………………………………………...
7 GROUND STATION [EARTH SEGMENT]…………………………………………………………………………………………………
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FOREWORD
What is OBC? ,OBC represents to an on-board computer, its mission is to handle and control the flow of the
command and instruction in the satellite itself in the space and it is responsible to fix the bugs in the satellite if it
was an option inside its commands,
INTRODUCTION
This group started to work together since the first year in their field in the college, and now we’re working on this
project, in this project we’re going to make mainly an On-Board computer, that contains; mission analysis, Linux,
LabVIEW modules, an interface with STK or (Satellite tool kit), we expect to make a subsystem that can handle
more than one satellite in the same time with the following method “Commander and followers”,
1 REFERENCES
[Abdullah Ali Abdullah] Simply raspberry pi, March-2014
[Maik Schmidt] Raspberry Pi a Quick-Start Guide
[Matt Richardson, Shawn Wallace] Getting Started
[Paul Cobbaut] Linux Fundamentals
[AGI] STK Fundamentals, December 21,2011
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2 Project Objectives
Mission analysis STK “Satellite Tool Kit”
Design and implement a Ground station GUI to control the satellite and communicate
with it
Design an On-Board Computer
Design a satellite mockup
Design and implement satellites modules " Commander and Followers” on the LabVIEW
Design an interface on LabVIEW that communicate with the satellites by using “DAQ
card”
Make an Intercommunication between the satellites themselves for example “Zig-Bee, or
laser communication”
3 RESERCH PRELIMINARY
3.1 Some Important Terms
Orbit The path of the satellite around the earth
Doppler A shift in frequency caused by satellite motion
LEO A satellite in Low Earth Orbit
HEO A satellite in High Earth Orbit
MEO A satellite in Medium Earth Orbit
GEO A satellite in Geostationary Earth Orbit “also HEO”
Uplink The frequency used to transmit to a satellite
Downlink The frequency used to receive from the satellite
Inclination The angle of the satellite where the equator = Zero
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4 ABBREVIATED TERMS
ADCS Attitude Determination and Control System
CDMS Command and Data Management System
COM Communication System
EPS Electrical Power System
HK House Keeping data
PCB Printed Circuit Board
PL, P/L Payload
5 WHAT HAVE THE STUDENTS LEARNT IN THIS PROJECT?
1. Linux Commands
-Directory Commands
ls: to list files
ls –a: list all files include all hidden files
ls –l: list with long format
tree: to list a tree of files
pwd: to show the current directory
cd: change the current directory
cd ~:to go back to your home directory
cd ..: to go back to the parent directory
cd - : to go to the previous
mkdir : to create directory
mkdir –p :when we use –p, then we can make directories as many as we
need
rmdir: when it is empty, you can remove the directory
-Files Commands
touch: to create file
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rm : to delete file
rm –i: to prevent yourself from removing a file by an accident
rm –rf: erase everything
cp : to copy files and directory
mv : move or rename files and directories
cat : to create a file and write/Read it
cat What_you_want_to_write_in_file > File_name
Ex cat what? > question this create a file called question and write
“what?” in it.
cat File_name
read whatever in the file and print it on the screen
echo: the same like cat
6 On-Board Computer code [Space Segment]
In this project we need to identify a constellation of satellites with an ID for
each one of them to but in this case we’re going to simplify it that for each
satellite, we have a button to press on, and then it sends a signal to notify the
ground station which satellites are “ON” , and for the 4 operation modes there
are 4 buttons to press on and when I press on one of the buttons that is
responsible for the operation mode it will send a telemetry to the ground station
for each mode a group of devices and sensors are “ON”.
For the following code, I used a Raspberry Pi board as an On-Board Computer
for the satellite itself, so when I press on a button it reads that press as input
signal on a pin, so it reacts to it, then it sends a signal on another pin to the
ground station to notify the ground station that, this is the satellite that is “ON”
now, [i.e. this is the satellite that is in the coverage area now to communicate with],
And in this code I’ve used a python code to program the kit.
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In this code it needs a user to write a command to execute the program, and in the space, I don’t
have a person that attached to the satellite , so I used the following command to make the
program runs with the boot
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and by experimenting it, it shows the following
Fig (1.1): wiring the Raspberry pi
Fig (1.2): wiring the
Raspberry Pi
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Fig (1.3): pressing on the first three satellites
in fig (1.3), when we press on a button it sends a signal to the raspberry pi to read “HIGH”, and
then it gives me an output signal on the Led, and the LEDs here represents the satellites.
The pins that I used for;
Input pins [31 , 32 , 33 , 35 , 36 , 37 , 38 , 40] from [ Push buttons ]
Output pins [16 , 18 , 19 , 21 , 23 , 24 , 26 , 29] to [ LED Bar ]
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7 Ground Station [Earth Segment]
in this part we need to build a GUI [Graphic User Interface] to use it to communicate
through it with the Satellites, display the telemetry [i.e. telemetry means the health status of the
satellite] and to download the payload data [ Images, Temperature degree, location, ……etc.]
starting with the
