I will do something similar to what is in the HALO project.
I am attempting to contact that project owner, although it looks like he is now in California (which is ironically closer to me than when he lived in Canada. We're big… we've got… HUGE TRACKS of LAND!!!)
I also have to give props to MrScienceMan on #highaltitude for indroducing me to his project.
APRS looks like it's an excellent way to go in the long run. For now though, I don't want to be limited by not being a Amateur Radio operator.
I've decided to use the following components for my first balloon payload.
Total weight so far: 215g
A good Canadian supplier of Balloons and parachutes!
With the Radio set to VOX (Transmit when talking), the GumStix can communicate without any PTT interface.
I won't know exactly how big a balloon I need until have the Payload built. If I can get everything built for under 250g, then I can get a cheaper balloon.
The electrical requirements are looking interesting. The GumStix seems to require 1mW of power when operating under a load. Three Energizer lithium batteries operating in series will give us 4.5V with over 9000mWh of life. I'm interested to see if it can sustain that with the cold temperatures. If it can, that's 9+ hours of life on three batteries!
I've enlisted a friend in Calgary to help me. I will be sending him the components and he will be launching and retrieving them for me.
I know this sounds like I'm stripping myself of the true joy of HAB: finding one's payload. Believe me though, that at these beginning stages there's a very REAL risk that that would not happen in my home province of British Columbia.
If it goes West: Ocean
If it goes North: You're hiking uncut brush past the first 10km
If it goes South: It's in the US and border chasing is not fun since there's an hour long line from 9-5 most days.
Your best option locally is to wait until the winds go East, and then you risk going into residential.
Calgary is a lot closer to vast areas of open, accessible land. The University there also has a HAB program.
He also has a small child who may want some Science-ing.
I've decided to simplify the payload of the balloon.
I've got some OpenBee 100mW transmitters, and a 7W booster. This thing should have some range!
The Bees have been paired, and I've got them on my own ad-hoc network.
All the Verdex has to do is pipe from /dev/ttyS2 to the USB device. I can do this with minicom using the following:
cat /dev/ttyS2 | `minicom -D /dev/ttyUSB0`
That will pipe the output directly to the USB device. Everything will transmit. It's received clearly in my test environment.
I'm sure I'll end up also putting a custom program in the middle of the pipe. There's no need to transmit that much data.
I'm also trying out integrating with GPSD. It has a convenient poll feature. For future reference, it listens on port 2947.
I figure I could even get so fancy as to use spare bandwidth to transmit images or telemetry.
I also added to the /etc/inittab so that I could log in wirelessly:
T0:2345:respawn:/sbin/getty -L ttyUSB0 115200 vt100
It's now September, 2013
I have managed to get more components working in tandem.
I now have the Gumstix booting and transmitting GPS data.
I'm working on writing a new send program, to minimize data sent. There are also a lot of xmit errors when you just pipe everything.
Here are some pics of the Gumstix running off of battery power.
I have a Battery pack made out of non-rechargeable batteries.
You can see a low-voltage meter on the rechargeable battery pack running the computer.
It's been going a few hours, and it's still going strong.
I have a better battery monitor coming, but this is encouraging as is.
I used an ESC from a model plane to get the 5V to power the Gumstix.
I had to hunt for the plugin adapter. I found one in a laptop multi-adapter kit. I didn't have to butcher the kit to get it working. I just took a power outlet plug from a Vonage adapter I had lying around to get it hooked up.
The cabling is too long right now, and I will rig something lighter up for flight, but for now this will do.
Currently the Gumstix + Transmitter + ESC + antennas + 8 AA battery pack is around 350g. Although the batteries are 125g of that, I think I should just consider this the base for my payload weight.
I might cut down the cables a little to save a few grams. The possibility of introducing error with crimping on new SMA ends is pretty hight though, so I may not.
Regardless, I will construct a little case for this so that it can be flown on my Bixler for in-air testing.