Pi In The Sky

Chris Stubbs

What’s in the HAB kit

• Balloon (keep this safe)• Parachute• PITS kit• Raspberry Pi Model A (for flight) + SD + Camera• Raspberry Pi Model B (for development)• Duct tape• Cord• Glue• Batteries• Foam

Raspberry Pi

• Low cost• Credit card sized computer• Plugs into:

– HDMI TV– USB Keyboard– USB Mouse– Ethernet

• Runs Linux OS• GPIO

Block Diagram

Raspberry Pi

Pi In The Sky Board

NTX2B Transmitter

uBlox GPS Receiver

Power Input

Pi Camera

What’s in the PITS kit

• PITS board• Battery holder• Battery connector• GPS antenna• Coax pigtail (for radio antenna)• Stand offs and screws

Power

• Raspberry Pi onboard regulator overheats

• PITS board contains better regulator• Energizer Lithium batteries perform

best in the cold• Higher energy density

GPS Antenna

• Ensure GPS antenna is connected to GPS socket!

• Clear view of the sky• No metallic objects above it• Correct way up

Radio Antenna

GPS Antenna

GPS Module

Antenna Pigtail

• Pigtail MUST be made into an antenna

Full Guide:http://ukhas.org.uk/guides:payloadantenna

Pi Camera

• 5MP Camera• 1080P HD Video (not

supported by default PITS SW)

• Lift clip on Pi and insert cable (silver contacts facing HDMI port)

• Press down on clip

Tracking block diagram

Receiver Setup

OR

DL-FLDIGI

RTTY

• FSK (Frequency Shift Keying)• Originally used on teleprinters (Baudot 5 bit)• Broadcasts continuous carrier wave• Shifts up/down in frequency depending on bit• We use 7 or 8 bit ASCII instead of Baudot• 8 bit allows for bytes of SSDV etc

SSDV• Breaks JPEG image up into small

packets (256 bytes)• Packets contain:

– Callsign of the sender– Image ID– Packet ID– Image dimensions– Error correction

• Packets can then be sent over the radio

• Packets are decoded and uploaded to internet

• Server reassembles packets into image

Balloon Tracking - EssexHam

Complexity levels

• 3 tiers depending on capability of students/teacher/mentors:– Basic

• Pre built image must be downloaded and copied onto SD card• Configuration text file must be edited• Hardware must be assembled (possibility of things like antenna pre made)

– Intermediate • Raspbian must be installed & configured• Software downloaded and built from source

– Advanced• Raspbian must be installed & configured• Software downloaded and built from source• Modification to perform an additional task (Video? Telemetry overlay?)

Setup• Install Raspbian

– Use a bigger SD card if you have one (4GB provided, 8GB would be better)– Flash up to date raspbian image using win32diskimager

Setup• Configure Raspbian

– Log in as “pi” password “raspberry” (raspi-config autoruns on first boot)

– Run “sudo raspi-config”– Expand filesystem– Enable camera– Enter advanced options:

• Enable SPI• Enable I2C• Disable serial shell

– Run “sudo halt” to shutdown to complete the setup (required)

• Connect camera, LAN and PITS board then update OS– Power on (from USB OR Battery) and Log in– Run “sudo apt-get update”– Run “sudo apt-get upgrade”

Setup• Install wiringPi GPIO library

– Change directory to home directory• “cd ~”

– Download wiringPi• “git clone git://git.drogon.net/wiringPi”

– Move into wiringPi directory and build• “cd wiringPi”• “./build” – This will take some time

• Install SSDV encoder– Download and build like above

• “cd ~”• “git clone https://github.com/fsphil/ssdv.git”• “cd ssdv”• “sudo make install”

Setup• Install PITS tracker software

– Download and build like above• “cd ~”• “git clone https://github.com/PiInTheSky/pits.git”• “cd pits”• “./build”

• Testing– Connect PITS board and camera

• “cd ~/pits/tracker”• ./startup

– You should see the red WARN light come on straightaway.– Once GPS lock has been established, the WARN LED will go out and the green OK light will flash.

Setup• Editing config file

This must be changed to your allocated call sign

Change to “N” to enable HDMI

This must be changed to your allocated frequency

Other parameters can be left as default

Setup• Habitat

– http://habitat.habhub.org/genpayload/– Create payload configuration document from existing “PI_SKY” config

• Change parameters such as call sign and frequency as per pixky.txt

– Once correct your payload should appear on http://habhub.org/mt once decoded with dl-fldigi

– Create a flight document to notify others of your flight and enable them to configure dl-fldigi with your settings.

Q&A• Slides can be downloaded from:

– http://chris-stubbs.co.uk/pits/pits.pptx

• Handy links:– http://habhub.org/ - Tracker, predictor, burst calculator, dl-fldigi, ssdv– http://ukhas.org.uk/ - Everything you need to know about ballooning– http://ukhas.org.uk/frontpage:guides – A set of comprehensive guides written by the community– http://ukhas.org.uk/ukhas:irc_channel - IRC chatroom (best place to ask for help)– http://www.pi-in-the-sky.com/ - PITS tracker hardware and software