Tag: balloon

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GPS on Raspberry Pi

Successfully installed this GPS board on the R-Pi.

By Kevin Townsend at adafruit.com

http://learn.adafruit.com/adafruit-ultimate-gps-on-the-raspberry-pi/introduction

The drivers for the console cable were already in the Raspian distribution on the R-Pi.

I installed the gpsd (daemon) software as directed in the above tutorial.

Documentation for gpsd is here:

http://gpsd.berlios.de/client-howto.html

Sample C code is: gpxlogger.c and cgps.c – which can be found in tkzic/rpi/gpsd 3.7/

(todo – write sample code and add to telemetry tracker)

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SSDV encoding, decoding, RTTY

I was able to packetize a jpeg file, send it using RTTY encoded audio, and decode using dl-fldigi to reconstruct the picture –  with a 33% error rate.

Details:

Encode jpeg file (note: file should be fairly small with dimensions that are multiples of 16) Using fsphil’s SSDV software:

./ssdv -e -c KA1IS -i 1 24.jpeg test1.pkt

decode:

./ssdv -d  test1.pkt test3.jpeg

RTTY:

Currently using multimode to encode and dl-fldigi to decode. dl-fldigi is the only software that internally supports the SSDV packets.

To get any results, RTTY must be at ascii, 8 bits, no parity, 2 stop bits. The other settings I will need to tweak for maximum throughput, but with this simple setup the error rate was way too high. Especially considering there was no radio involved.

Any way it sort of works

 

 

 

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Balloon project

notes

Cost estimates rising. I think we’re looking at around $700 possibly more. The balloon, parachute, and helium costs are fixed. Need a source of helium. Might try the sun.

Tracking options:
  • Commercial service like Spot messenger GPS. $100 plus annual service fee of $150
  • Amateur RTTY + GPS – Have built a prototype using arduino. cost will be about $120 – but arduino can be used for many other purposes. Can be tracked by anyone with 70cm receiver. ie., all hams.
  • Amateur APRS – Allows worldwide automatic tracking via APRS network. Cost will run about $250 but provides the most extensive automated tracking network possible. Recommend using Byonics equipment for this.
  • Xbee 900mhz 9600 baud radios (from Sparkfun electronics) These radios provide accurate long range tracking, and interface easily with arduino. Down side is that nobody else can track the flight.
  • Emergency GPS tracker units. Like the ones that skiers use. Haven’t priced these but they would provide a way to find the payload long after it lands.
Sensors:

Recommended sensors would include temperature, pressure, altitude, light levels. These should be fairly inexpensive and can be connected to Arduino

Cameras:

Originally I had wanted to have some kind of live web cam thing, but it appears to require extremely high rate of radio transmission which means live tracking with a mobile unit that has a high gain antenna with programmable azimuth and elevation.

So… logistically, the easiest alternatives then involve the need to recover the payload. These include

  • ordinary camera which is triggered at regular time intervals
  • video camera which runs all the time
  • web cam hooked to a raspberry pi which saves data to SD card
  • web cam/ sd card combo controlled by arduino – more difficult.