26 July, 2014AMSAT-UK Colloquium 2014
Lituanica SAT-1
Gintautas SulskusAMSAT-UK International Space Colloquium
July, 2014
26 July, 2014AMSAT-UK Colloquium 2014
Lituanica SAT-1 team is very grateful to
radio amateur community
for all support and enthusiasm!
Thank You!
26 July, 2014AMSAT-UK Colloquium 2014
Driven by the Idea
• Launch the first Lithuanian satellite
• Take the first photo from space
• Stimulate collaboration between universities
• Raise the interest of general public
• Create a platform for future projects
• Create new opportunities for business and education
26 July, 2014AMSAT-UK Colloquium 2014
The Mission
Article about the first Lithuanian satellite
Jul 2012
Launched by Antares, aboard Cygnus
9 Jan 2014
Ejected from ISS
Re-entry
~29 Jul 201428 Feb 2014
Sent-off to NASA
Oct 2013
Development The wait Impatience Fun
1. Core team2. HW Dev3. New competitor4. SW Dev5. Testing
1. First contact!2. Comm problems3. Brownouts4. Finally, got under control
26 July, 2014AMSAT-UK Colloquium 2014
• ARM module (OBC)
• Comms with GS, SAT control
• Peripherals
• URAT - commands, data transfer
• I2C - EPS control, telemetry, WD
Lituanica SAT-1
Lituanica SAT-1 Architecture
ARM module
Arduino module
Electrical Power System
UART
I2C multi-master
FM Repeater
Ground Station
Transceiver
UART
26 July, 2014AMSAT-UK Colloquium 2014
• Arm Cortex M4F
• 32 bit, 192kb Ram, 92 MHz, 3.3V
• Downclocked
• Sensors
• Gyro, accel and magnetometer
• SD Card
• Telemetry data storage
• Watchdogs the link with GS
ARM module
26 July, 2014AMSAT-UK Colloquium 2014
Helium-100
• FSK/GMSK transceiver
• Frequencies
• TX: 120-150 MHz or 400-450 MHz
• RX: 400-450 MHz or 120-150 MHz
• Sensitivity: -104.7 dBm @ BER 10-3
• Max bandwidth: 38.4kbps, full duplex
• AX.25 protocol
26 July, 2014AMSAT-UK Colloquium 2014
Arduino
• Atmega 2560V-16AU
• 8bit, 8MHz, 8kb RAM, 3.3V
• Beacon
• Message updates, ON/OFF
• Camera
• SD Card
• Photo storage
• Watchdogs ARM
26 July, 2014AMSAT-UK Colloquium 2014
Arduino Module: BeeLine Radio Beacon
• FM or CW modulation
• Frequencies 420-450 MHz
• Transmitter power -20 to +12 dBm
• Starts independently
• Guaranteed communication
26 July, 2014AMSAT-UK Colloquium 2014
Arduino Module: Camera
• VGA 640x480
• JPG compression
• Automatic exposure
• Manual focus (infinity)
• Fisheye lens
26 July, 2014AMSAT-UK Colloquium 2014
Selfie
26 July, 2014AMSAT-UK Colloquium 2014
Electrical Power System
• GOMSpace - NanoPower
• 3.3V@3A and 5V@3A
• fully controllable channels
• Predefined power modes
• Blackout, Brownout, Safe, Nominal
• Watchdogs I2C bus
26 July, 2014AMSAT-UK Colloquium 2014
Electrical Power System: Solar Cells
• Silicon based
• Custom built
• Low cost
• Still in good condition
26 July, 2014AMSAT-UK Colloquium 2014
FM Repeater
• TX 433.550 MHz
• RX 145.575, 67 Hz CTCSS
• Only 2 more in orbit
• Saudi SO50 - full time
• ISS - activated manually
• Feedback
• Good conn quality & pwr efficiency
• Simple equipment for comm
26 July, 2014AMSAT-UK Colloquium 2014
FM Repeater Prototype
26 July, 2014AMSAT-UK Colloquium 2014
Key System Requirements• Fault tolerance
• Failures anytime, anywhere
• Redundant component control
• Via SW and HW power channels
• Watchdogging
• Power modes
• Safe, Nominal, Science
• Lightweight Network Protocol
• commands, packet data transfer
26 July, 2014AMSAT-UK Colloquium 2014
• An attempt to leverage formal methods
• Requirements specification in natural language
• Translation to mathematical model (Event-B formalism)
• Stepwise refinement of SAT states
• Correct requirements according the mathematical model
• Barely scratched the surface
• Still highlighted some inconsistencies in requirements
• Time consuming, slow
Experimental Requirements Specification
26 July, 2014AMSAT-UK Colloquium 2014
Abstract level: Physical On/Off
26 July, 2014AMSAT-UK Colloquium 2014
1st Refinement: Control Zones
26 July, 2014AMSAT-UK Colloquium 2014
2nd Refinement: Power Modes
26 July, 2014AMSAT-UK Colloquium 2014
3rd Refinement: Operational Modes
26 July, 2014AMSAT-UK Colloquium 2014
Implementation Decisions
• Good old C for SAT• Keil RTX for ARM
• Arduino package for Atmel
• Ground Station
• Erlang
• Communication
• Lightweight UDP-like network protocol
• Developed in-house
26 July, 2014AMSAT-UK Colloquium 2014
ARM SW Architecture
Scheduler[max 10 CMDs]
Runner
Background Operation Tasks(On/Off)
● Telemetry● Housekeeping● Power manager
(Always ON)● Scheduler
Schedule CMD[Received CMD]
Create Runner task[Delay=0]
Continue with CMD[PowerMode=OK
andOpMode=OK]
• Background tasks always initiated
• No new tasks are ever created
• All cmd’s go into scheduler
• Operations run as tasks
Discard CMD[PowerMode=FAIL
orOpMode=FAIL]
Remove from Scheduler stack
Lib Stack
26 July, 2014AMSAT-UK Colloquium 2014
Success Criteria
• Minimal
• Get it launched
• Deploy antennae
• Possible problems in the first few weeks
• Receive radio beacon signal
• Nominal
• Establish SAT-GS communication
• Test FM repeater
26 July, 2014AMSAT-UK Colloquium 2014
Success Criteria
• Maximum
• Satellite stabilisation
• Receive telemetry data
• Take photo
• Misfortune
• Telemetry archiving to SD card does not work (ARM module)
• Pleasant surprise
• OSCAR-78, or LO-78 award!
26 July, 2014AMSAT-UK Colloquium 2014
The First Photo
26 July, 2014AMSAT-UK Colloquium 2014
Lessons Learned
• Operators struggled to use the satellite
• Confusing functionality: overlapping EPS and ARM power modes
• Poor\Lack of documentation… or reluctance to read it :-)
• “Do it quickly and make it right later” does not work! Do not try!
• All timers must be configurable!
• Use homogeneous environments for reusability (e.g. only ARMs)
• Reflash option
26 July, 2014AMSAT-UK Colloquium 2014
Thank You!
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