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High Altitude/Near Space Ballooning

Former Member

I have experimented with electronics for a while. Very few of my projects have been useful (if finished). So I wanted to settle in on a project for a few months that I can learn form. Allot of people have created near space balloons, and I want to join the club! The basic idea of a near space balloon is to build a case with a GPS, small flight computer, sensor array, and cameras. Then send the creation to near space (around 85,000-110,000 ft in most cases).

 

The case, balloon rigging, parachute, and cameras will be easy enough to build.  So I decided to start by designing the flight computer and associated systems. With any luck, the engineering process is going to restrain me from running in full speed and getting everything backwards. I started by deciding on the requirements.


The flight computer must:

  • Receive data from onboard sensors
  • Interpret and record the data with time and or location stamps
  • Retain data in the event of a loss of power
  • Transmit GPS location and altitude to the ground
  • Be fairly light and small
  • Function at near freezing temperatures

 

The only experience I have with micro controllers is with the Arduino environment on the ATMEGA328. This is a very basic language and slow, but it should work for me. After a little thinking and a few tries, I came up with an O.K. design that met the requirements. It consists of a main board and a second sensor board. I am detecting humidity, inside and outside temperature, acceleration, and barometric pressure. With the exception of the humidity sensor and accelerometer, the sensor network is on the I2C bus.

 

The only thing left to do as far as the flight computer design is concerned is to create a system for logging the data and sending the GPS data down to earth. I would like to log the data onto a text file on a SD card so I can quickly move it to my laptop upon recovery. If each sensor could log into its own separate .CSV file that would be handy. I also need suggestions on the system for sending info down to earth.

 

I have included copy of the schematic and board files for Eagle if you are interested in reviewing them. Remember THESE ARE NOT TESTED so if anything blows up because you used this board, it's your own fault. I would love to hear any comments, suggestions, or ideas you may have. Thanks!

Attachments:
board files.zip
  • in reply to shabaz

    I do understand GPS has a high limit (FL600) and hopefully that wont be a problem. I hope to get at lest FL950 hopefully FL110 or more... I need the data to be stored somewhere that wont get erased when it powers down (RAM deletes after it loses power right?). The only thing I need to send down is the GPS data, and I don't have any radio licenses or anything so I was looking at SPOT. As far as the cold is concerned, I am going to test my equipment and see if it can hold heat (if not the thing to do seams to be hand warmers). Thanks for your help!image

  • Hi,

     

    It sounds fun. I've not seen the schematic (might want to post a jpg image to make it easier for people using mobile devices, etc).

    Some comments:

    GPS has a height restriction so you may need to rely on barometer if you get really high

    Also, as a suggestion, you could also consider maybe just log to RAM or a local non-volatile storage, rather than transmit.

    For tracking, an option which doesn't require you to spend time/effort constructing a receiver is to just transmit via radio just morse code of the GPS co-ords for you to record and play a few times to manually interpret, which is feasible even if you don't know morse code. Or, I'm sure there must be free software to do this decoding if you plug the audio from the radio into a laptop (might affect your radio reception though).

    You could transmit just occasionally for you to estimate the direction, and transmit more frequently as it descends maybe - I don't know what the flight profile of a balloon is ; )

    Edit: Sorry, just ready your post in a little more detail. I think there are some arduino libraries for writing to an SD card, so you should be ok. Your code doesn't need to write in .csv format, since you can post-process the data on your PC. Beware that temperatures will be very extreme, so ensure you're using reliable connectors, a suitable battery, etc. There must already be good forums on ballooning with this type of information I guess. Keep the code simple so that even if nothing else works (e.g. card writes fail or the GPS module or some sensor doesn't respond), at least it can transmit beeps when descending.