Good progress is being made with our Balloon launch plans. We have acquired an Android Phone (HTC Droid Eris). It has been programmed to send back GPS Coordinates and take pictures every 30 seconds. It sends back pictures via email every couple minutes. Here’s a picture it took and emailed back to me as I was on my test drive of the phone software.
The GPS coordinates are sent back via SMS message, email, and through hits on a website that I created:
This allows me to track the balloon on Google Maps in real time. If/When the balloon goes out of cell phone range there will be silence, but hopefully when the phone gets back in cellphone range, it’ll start transmitting its coordinates again.
I got a 20 ft weather balloon. (check)
I got a styrofoam airplane as the landing device. (check)
Here are the problems:
1. The phone GPS accuracy is not great… In fact it’s about 1/4 to 1 mile off.
Here is once example. I was sitting in the parking lot (blue circle) of where I work for this GPS reading. The Red Dot is the GPS reading. If the phone lands in the woods, this is a LARGE area to search. There are some readings that are up to a mile off.
So, at this point, I don’t think there’s anyway we can get around putting together a beacon so that we can do some kind of RF direction finding. This is all new to me, so we’re trying to figure out what kind of beacon will work best. Coincidentally, I’m studying for the Amateur Radio Test which I hope to take in September. Depending on the frequency used, this might be useful.
2. Here’s the other big problem. I used the Balloon Trajectory Forecast site to see approximately how far my balloon will go. This site uses the most recent weather information to predict where the balloon will land. if you launch it near our house, it will land in…. well… there’s no name for it… it’s not a city… it’s on top of the Cascades…
All I know is that on Google Earth, it’s showing snow and there are no road for many, many miles…
This means that we can’t just schedule a day and place to launch. We’ll have to keep an eye out for weather patterns, then figure out different launch sites so that the balloon will come down somewhere accessible…
We’re getting closer… This is my completely unscientific assessment of success probabilities:
|Launch Balloon||Will we be able to fill the balloon without popping?
Will we be able to setup the rig so that it all flies off?
Is there enough helium?
|Get at least one aerial picture||Will the software run as planned?
Will the phone be in range when it triggers the first email?
|Get the location of the phone after it has landed within 1 mile||Will the software keep operating?
Will the phone have connectivity where it lands?
Will the phone be in one piece and operating after it lands?
Will the phone operate through the cold temperatures of high altitude?
Will the phone battery last the entire journey?
|Successful Retrieval||Will the phone land somewhere accessible?
Will the GPS signal be close enough so that we can find it?
Will we able to use RF direction finding techniques to locate the beacon?
Will the beacon battery last?
Is this too optimistic? Am I sandbagging? Leave a comment.