Tuesday, September 25, 2007

I found out where balloons go...

The space balloon launch was a total success. The first one sank to Earth. We added more Helium and the second flight rose about 20ft before crashing into some trees and power lines. Luckily the tree ripped the FAA-required radar reflector off of the craft and then the balloon rose over the treeline and was on its way.

We relocated to Panera Bread in Rolla and watched the Internet and data packets as the balloon climbed to ~30,000ft, where it took off like it had a rocket up its ass. By the time we got into cars and on the road, it was at 52,000ft. We sped to Jeff City where Mark knew an amateur radio guy whose name I didn't get. We watched the internet for about 15 mins before the balloon burst when it was at 96,649ft and the payload fell to Earth near Ashland, MO.

At the bottom of a 200ft deep canyon. And it landed 50ft up a tree. With no limbs. Really. The rest of the party carefully hiked down into a canyon where the tree was located, and I took the express route. I slipped, fell, rolled down about 50ft, scraping and cutting myself *all over*, coming to rest when my back struck a solid tree.

We were lucky. I could walk and didn't have to be extricated by helicopter. When we got to the top of the canyon, we met the guy that owned the place. He was a great guy and not only let us cut the tree down, but gave us the axe to do it and gave everyone Cokes/beer/water and let me clean up at the pump after my fall.

"You'll have Poison Ivy. If you get it." Oh, good.

The APRS tracking system worked perfectly. We were heard as far as Tennessee and Ontario, Canada using only a 3 Watt handheld transmitter. The onboard battery continued to transmit for another two hours after touchdown while others in the party cut the tree down. We got the payload back in excellent condition with the exception of the antenna, which had a couple of broken dowels and will have to be remade. The onboard M&Ms were all cracked, but they're fine, and will be sold on eBay ASAP.

Best news is that I apparently don't get Poison Ivy/Oak.

Now I know where the balloons go - Ashland, MO.

More pics here.

B

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Wednesday, September 12, 2007

Call me Levon...

Have you ever wondered where those balloons go when you let go of them? Me too. And I'm about to find out.

Recently some friends were standing around my office when someone found a pic shot from 100,000ft. And it was the coolest pic I've ever seen.

Someone says "Hey, we could do that!" And that was all it took to convince a group of otherwise intelligent people to all think all at the same time "Lets put a balloon in space!"

OK, I have nothing else to do with the next three months of my life, so whatever.

How hard could it be? Nothing to it, right? Camera and a balloon. Except that it gets cold at that altitude, so you need some insulation around the camera to keep the battery working. And it still gets cold, so you need a special type of Lithium to work at -40C. And if you over-discharge the battery, it's dead for life. OK, so balloon, camera, Styrofoam cooler, and Lithium Ion battery with protection circuitry and a special battery charger that charges each cell individually, because if you don't, they might just blow up and kill you or set the house on fire.

And if we ever want to see the camera again, we better be able to find it when it lands. Hey, wait a minute - it does land, doesn't it? Well, it really depends on the type of balloon. If it's Mylar, it may take a month to come back. But it turns out that weather balloons are built to burst at a specific altitude around 100,000ft - just what we wanted! OK, so $65 special balloon, camera, cooler, battery, battery charger and a parachute to recover the camera safely when the balloon pops.

Wait - how do we get the camera back? We could stick a note on it so that people could call us when they find it. Except that's how my friend got the digital camera he has - by not calling the number on the lost camera he found. Guess we better track it. It needs a GPS on board to be able to tell us where it is, that part is clear. And it needs something to read the GPS and phone us with that info. First plan was to use a cell phone to text us the coordinates, but no one knew if a cell phone worked at 100,000ft - that's at least 20 miles from the nearest tower! We saw that other balloon groups used amateur radios to send their info back. APRS was developed for the purpose of remote tracking. That was good enough for us. So for APRS you need a Serial GPS, an interface that reads the serial GPS data stream and converts the data to AX25 packets which are transmitted via the amateur radio to repeater towers, where the data makes its way onto the internet. Research showed that most GPSes made have a 60,000ft limitation, so we had to choose a special Garmin GPS18 serial GPS that works at over 60,000ft. We found a device called a TinyTrack 3 that converts the serial stream from the GPS into AX25 packets for the amateur radio, but one of us heard from another guy that no one really knows that TinyTrack 3's suck, so we have to find something else. We found a guy that used one of his own products to safely recover his balloon, so we bought an Open Tracker 2 OT2m radio modem. Except the OpenTracker didn't exactly come with any manual or any documentation. The radio is a Yaesu VX-2R, which was cheap, small and lightweight. The radio didn't work as-is with the battery, so I built an adjustable voltage regulator board. OK, so all we need is a $65 balloon, a camera, cooler, and a parachute, Garmin GPS18 Serial GPS, an OpenTracker OT2m radio modem, battery, battery charger, special cable, and Yaesu VX-2R amateur radio.

Most of the stuff arrived about two weeks ago and we got together to configure and test everything. First thing was that the OEM GPS had to have a special cable made that would provide +5VDC to the GPS, and that would connect to the serial port on my computer for testing. Then it turns out the GPS takes forever to get a lock and doesn't work if it's anywhere near a building. At all. So it took a couple of days to get the GPS to output coordinates other than Garmin HQ. When it did, they were in units of fractional degrees (38.123456 degrees), not degrees/Minutes/Seconds. So without a lot of converting, Google Maps shows the wrong location. Next problem was that the radio was receiving packets from the repeater tower which the OpenTracker was decoding, but the radio was never transmitting. After about 10 hours of unnecessary trial and error and analysis on the radio mic, we reasoned out the radio data cable we needed to build, and sure enough, it worked. We went to findu.com, searched for our call sign, and sure enough - we were transmitting GPS data info to the internet! The pizza arrived and all was good for a little while, and then it all went wrong. We were using an wall transformer power supply to power the GPS and OpenTracker, and we were switching back and forth. The GPS required 5Vdc and the OpenTracker requires at least 6.5Vdc. And when I forgot to reconfigure the voltage on the power supply and applied 6.5V to the GPS, it died a silent death. OK, so all we need is a $65 balloon, a camera, cooler, and a parachute, Garmin GPS18 Serial GPS, a Garmin GPS18 to replace the dead Garmin GPS, an OpenTracker OT2m radio modem, battery, battery charger, special cable, homemade voltage regulator to power the radio, Yaesu VX-2R amateur radio, laptop and smart phone to connect the laptop to the internet.

Then someone got the idea to track this thing using an aircraft with radio direction finding equipment. OK, so we're going to need a way to communicate with the ground, a way to find the balloon, another radio operator, a cross band repeater and a couple of homemade antennas that we can mount on the aircraft for the comms, another antenna which will be used for direction finding, another GPS for the aircraft, a $65 balloon, a camera, cooler, and a parachute, Garmin GPS18 Serial GPS, a Garmin GPS18 to replace the dead Garmin GPS, an OpenTracker OT2m radio modem, battery, battery charger, special cable, homemade voltage regulator to power the radio and Yaesu VX-2R amateur radio, laptop and smart phone.

Oh, by the way. The airport where the aircraft is based has a radio receiver that pilots use to turn on the landing lights. You guys are good with electronics - how about if you look at it? It's been out for a month or so. Three hours later and it's working.

The plane radio tests were conducted last Saturday. We were able to communicate with the plane. We were able to place the radio tracking device in the plane and fly it around and see the coordinates popping up in real time on the internet. Sweet! We attempted to receive the packet data from the balloon itself (using another handheld amateur radio) and decode them using the soundcard in my laptop, but the cable wasn't right and that test failed. The best part was that it was raining all dang day, and yet no one bailed out because of the rain - stuff still got done! When we analyzed the data, we saw that it stopped transmitting coordinates toward the end of the flight. Not a good sign.

Today I was able to determine that inserting a mono cable into my Dell laptop Microphone port shorts the thing out entirely. OK, so I'll use a stereo cable. But then I learned that only one of the two channels in the stereo mic port is actually connected. The left one. So one more special cable and I was able to decode info from the OpenTracker and from the repeater tower using the laptop. So far, the experiment requires two radio operators, a cross band repeater and a couple of homemade antennas that we can mount on the aircraft, another antenna which will be used for direction finding, GPS for the aircraft, a $65 balloon, a camera, cooler, a parachute, Garmin GPS18 Serial GPS, a Garmin GPS18 to replace the dead Garmin GPS, an OpenTracker OT2m radio modem, battery, battery charger, special cable, homemade voltage regulator to power the radio and Yaesu VX-2R amateur radio, laptop and smart phone, special audio cable to connect laptop to second radio, and software to decode packet data.

The internet coordinate data will be good enough to get us close, so long as it works. But what if the radio stops transmitting to the internet during the balloon flight? With luck, the radio will still respond to a ping request from another radio. The aircraft direction finder may or may not get us closer (it hasn't been tested yet), but what do we do when we're on the ground? OK, so we need another handheld radio and a direction finding antenna. And two radio operators, a cross band repeater and a couple of homemade antennas that we can mount on the aircraft, another antenna which will be used for direction finding, GPS for the aircraft, a $65 balloon, a camera, cooler, a parachute, Garmin GPS18 Serial GPS, a Garmin GPS18 to replace the dead Garmin GPS, an OpenTracker OT2m radio modem, battery, battery charger, special cable, homemade voltage regulator to power the radio and Yaesu VX-2R amateur radio, laptop and smart phone, special audio cable to connect laptop to second radio, and software to decode packet data.

Then someone gets the idea to test the equipment at the actual temperatures we'll be experiencing at altitude. Dry ice. Except that they don't sell it in our town or any town within 50 miles of here.

So Saturday morning at 7am we plan to cram all this stuff in an even larger cooler, pack it full of dry ice, put it in a car and drive it around for four hours to test the reliability of . We'll test locating from the ground, locating from the air, operating in cold temps, tracking the payload capsule, and our ability to maintain a fix on the payload while stopping every 5 minutes to buy more Fritos to feed the computer geeks staffing the mission.

Assuming all goes well, launch date will be 9/23/2007.

Bryan A. Thompson
bryan@batee.com

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