From High altitude

Contents 1 Pong 1.1 Things that worked 1.2 Things that did not work 1.3 Conclusion 1.4 Pictures

[edit] Pong

Weight: 1400gr

On board

• Microtrack APRS transmitter.
• Polaroid digital camera with batteries. No LCD.
• Fit PC
• Webcam
• GPS
• 5 volt power converter for PC. The PIC controlling the camera is on this board.
• GPS Splitter board, feeds both the PC and microtrack with GPS data. This board also converts power for the GPS and Microtrack.
• 6 lithium AA batteries feeding the GPS and microtrack.
• 8 lithium AA batteries feeding the PC

[edit] Things that worked

Balloon filler

The balloon filling mechanism was easily the best part of this launch. It might not sound like much, but without it our balloon would have not been filled or would have got loose.

If you ever tried to fill a weather balloon while there is a wind you know what I am talking about.

Its made from a party balloon filler and some pluming and gas parts from Lowe's. We where afraid that it would break under the pressure from the helium tank. This was not a problem.

Microtrack

A Micro-Trak 8000 FA did the APRS transmission. It behaved wonderfully. The only bad thing I can say about it is that we did not make it ourself.

Next time we want to try to make a 2mhz transmitter that transmits the location using morse code as a backup. The 144mhz APRS signal does not transmit very far. If we had something like that this time we would probably have been able to receive from the balloon when it was on the ground.

Base station

We had a Yaesu FT-7800A mobile radio in our car. We connected it to the sound card and a parallel port on a laptop. We used the AGW packet engine and AGWTracker to recieve and transmit APRS signal. We used Microsoft map point to track the balloon and the car (AGWTracker interfaces to this program). We also used USAPhotoMaps to view high res photos of the landing location. USAPhotoMaps is a fairly poor map program, but you can download all of California to a hard drive and browse off line.

It was probably a mistake to broadcast the car's position on APRS, sometimes we missed the transmissions from the balloon. We could not find a way to log the packets to disk either.

Next time we probably want to write our own programs, we are software engineers after all. Johan did some research on how to download the maps from google maps and NASA has height data down to 6x6 meters for all of USA. We also recruited another engineer to help us with this software.

Power

[edit] Things that did not work

USB IO board

We did a PIC18F4550 based USB board to use with the PC. We found out 2 days before launch that USB and radio transmissions does not work that well together. The USB board would kill the UBS hub, or even crash the PC when we transmitted.

PC radio transmission

Instead of the IO board we used a USB serial cable to trigger the PTT on the FX-3R. It worked, but the PC would sometimes crash when we transmitted. We could probably have solved this, but it was late on Friday, and we wanted to finish up. I think our PC motherboard was extra sensitive.

We had grand plans of logging on to the PC during flight, transmitting back images and other stuff.

PC

At the end, the PC only had a web cam and GPS attached to it. It logged the GPS data and saved web cam jpeg's.

But... It crashed while we where filling the balloon, we don't know why and we did not notice. It did come back up when the ballon landed on the ground according to the logs. Nice...

This is easily the worst part of the whole project. Martin is planing to do something nasty to it.

Christian is designing a CPU board using one of the Philips LPC CPU's for our next flight. It will have 32MB of memory and run uLinux. Its great to have an electrical engineer on the team.

Camera

The camera was a cheap Polaroid camera. We hooked it up to a PIC16F505 using a relay to take pictures every 30 sec.

When we assembled the payload on the launch site we put new batteries in it. It did not want to turn on. We put the old batteries in and removed the LCD. We also noticed that the flash was on. Since we had removed the LCD we could not find out how to disable it. We did not have time to fix it.

In the end it took pictures for 20 mins before giving up.

I don't blaim the camera, we should have hooked it up to the main 5 volt source used by the PC.

[edit] Conclusion

It is a bit disappointing that we did not get any pictures from near space and much of the planned hardware just did not work.

But, it was amazing to see the balloon take off and chasing it was so much fun. We ALMOST made it to 100k feet!

[edit] Pictures