Lituanica SAT-1...AMSAT-UK Colloquium 2014 26 July, 2014 Lituanica SAT-1 team is very grateful to...

26 July, 2014AMSAT-UK Colloquium 2014

Lituanica SAT-1

Gintautas SulskusAMSAT-UK International Space Colloquium

July, 2014


Lituanica SAT-1 team is very grateful to

radio amateur community

for all support and enthusiasm!

Thank You!


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


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


• 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


• 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


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


Arduino

• Atmega 2560V-16AU

• 8bit, 8MHz, 8kb RAM, 3.3V

• Beacon

• Message updates, ON/OFF

• Camera

• SD Card

• Photo storage

• Watchdogs ARM


Arduino Module: BeeLine Radio Beacon

• FM or CW modulation

• Frequencies 420-450 MHz

• Transmitter power -20 to +12 dBm

• Starts independently

• Guaranteed communication


Arduino Module: Camera

• VGA 640x480

• JPG compression

• Automatic exposure

• Manual focus (infinity)

• Fisheye lens


Selfie


Electrical Power System

• GOMSpace - NanoPower

• 3.3V@3A and 5V@3A

• fully controllable channels

• Predefined power modes

• Blackout, Brownout, Safe, Nominal

• Watchdogs I2C bus


Electrical Power System: Solar Cells

• Silicon based

• Custom built

• Low cost

• Still in good condition


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


FM Repeater Prototype


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


• 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


Abstract level: Physical On/Off


1st Refinement: Control Zones


2nd Refinement: Power Modes


3rd Refinement: Operational Modes


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


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


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


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!


The First Photo


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


Thank You!

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