Balloon Launch Recap

Friday, August 16^th: The Night Before the Launch.

This night consisted of fixing the capsule and checking that the Arduino returned the right coordinates across the walkie-talkie.  Little known fact; we designed and built the parachute mechanism that night, without any testing or much planning.  After several hours we finished everything at 2:20 AM and went to bed

Saturday, August 17^th: The Launch and Recovery

Waking up at 3:30 AM, I felt more tired than before I went asleep.  We packed the truck and were leaving at 4:10 AM.  It was a much shorter trip than last launch, taking 90 minutes to drive there.  Arriving at Perrydale high school in Perrydale Oregon, the launch site was better than could be expected.  The only hazards were the track lighting which surrounded the field.  Given that our nozzle lift was much higher than last time, these lights weren’t going to be a problem.  Since we arrived early in the morning, the wind had not yet picked up.  The skies were clear, and it seemed like the launch would go well.  Rolling out the tarp, Lee started on the balloon while I organized the payload.  For what seemed like an eternity I stood around and watched Lee fill the balloon because assembling wasn’t going to take a long time.  I had gone through the motions of assembling the capsule the night before, so I waited until 25 minutes before launch to start assembling.  The main reason we did this was to give the GoPro as much in flight battery life as possible.  On our previous launch the GoPro batteries died before the balloon even popped.  Furthermore, we added a battery stick which connected to the GoPro’s mini USB in order to prevent total power failure.

This is where the fun began.  In reassembling the foam interior I ran across some interference with the walkie talkie.  Additionally, the Arduino was not sending back the right coordinates.  It took us around 10 minutes to realize the batter powering the Arduino was creating an electric field which messed up our transmission.  Hacking away at the foam I oriented the battery lines farther from the GPS.  Once this was finished, the transmissions which were irregularly spaced started to send as coded.  As a side note, we probably should have done much more exhaustive testing and cleaned up the code for the Arduino, but we didn’t.  All seemed well and we began taping the rest of the capsule.  Right before we started taping my phone in place the walkie talkie lost power.  They had been almost fully charged the night before, so we were very confused as to why this happened.  Switching batteries between the walkie talkies, we reassembled the capsule while charging the other battery.  At this point, Lee and I just wanted to launch the balloon, problems and all.  Although this took place in less than half an hour, the stress from problematic electronics and a diminishing launch window was immense.  We eventually fixed everything and let it go.

It was a relief to let go of the balloon, considering that if everything but the GPS on my phone failed, we would still be fine.  I then predicted that the walkie talkie would run out of power in 90 minutes.  It lasted 20 minutes.  You could say that the constant use of a walkie talkie on Hi-band consumes quite a bit of power.  We probably should have done more math regarding its duty cycle.  However, with the loss of our primary form of communication/location, my cell phone had not yet died.  We actually managed to send back photos from my phone during the trip.

 

Compared to our launch last year recovery was easy.  The nozzle lift was much higher than the previous balloon, limiting the balloon’s overall time in the air.  It landed in a field bordered by thick trees and a road.  We were very glad that it landed where it did, considering the amount of local tree farms.  Unfortunately, the GoPro was turned off when we found it.  The capsule was slightly damaged, but landed properly nonetheless.  Using a program found online, Lee managed to reclaim most of the footage that was damaged in the landing.  If you look closely, right before the camera hits the ground the video starts to become grainy.  Although we were disappointed that the footage of the capsule hitting the earth was lost, I was glad nothing was permanently damaged.

 

Despite the failure of the GPS recovery system, we consider the launch to be a great success, and we were able to capture some amazing footage. Our video can be seen at: https://www.youtube.com/watch?v=W-lo2QAYHZQ

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Tracking Device Progress

Once again, it's been a while since I've made a new post (seriously, it's becoming cliche). But that doesn't mean we haven't been working hard at our project. In fact, we've made some serious progress on the Arduino based tracking device. After realizing we had a major oversight concerning radio communication, we decided to change our methods from serial communication to DTMF (Dual Tone, Multiple Frequency) communication. Don't know what DTMF is? You know the sound you hear when you push a number on your telephone? It's that. The tones you hear through your phone are actually a combination of two frequencies. Each number on the phone corresponds to a unique combination of two of a set of frequencies. When the telephone station (or whatever it's called) receives these tones, it recognizes the combined frequencies as a set of numbers, and takes action accordingly. What exactly does this have to do with our project? Well, because audio signals transmit over radio much better than binary signals, we've decided to use dual frequency signals to communicate the latitude, longitude, and altitude values. We have an IC (integrated circuit) that will take in binary data and convert it to these tones, so we can easily plug output of this chip into the mic of a radio, and plug the speaker of the other radio into a computer to interpret the signals.

DTMF tones of different numbers

So we have a language to communicate the data, but we also need a way to get the data. You may think it's pretty simple, just take the GPS data and plug it into this magical chip. However, we have to convert the GPS data, which is stored in "float" (a type of variable which has numbers after the decimal point), into an array of numbers, so that they can be called individually. After a long time programming, filled with frustration, we finally got it. The video you see below is the GPS data being converted to individual numbers, and then displayed sequentially as binary numbers in four bits. It's probably hard to tell what the numbers are because the LED's are so bright, but the sequence is 2,6,3,7,8,0,3,7,8,4,0,0, and then it repeats again after all the LED's go on. This means that the location in "minutes" (1/60th of a degree) is 26.3780 by 37.8400. I disregarded the degrees because the balloon's trajectory should not cover more than a degree of latitude, and if it does, we'll know which degree area it is in anyway.

Now, all that's left is to get all of the hardware ready and test the range of the radios. That's still a lot of stuff to do, and we only have under 3 weeks left. This is the part of the project where stress levels rise to a record high. I'm fairly confident we can get all of it done, but we're nowhere near where I thought we'd be at this point. What's left on the shopping list? The balloon, the helium, and any materials we need to fashion the capsule. Oh yeah, and another unexpected cost came up recently. As it turns out, the radio range of 40+ miles is only reachable in the GMRS setting. And the FCC requires you to have a license to operate the GMRS channels. And the license costs $85. Yeah. Donations, anyone?

Update

There hasn't been a blog post in a while, so I figured I'd give everyone an update. 

We've finally collected all of our electronics equipment for the tracking device. I say that with some reservations, however, after making three or four separate shipments from the same electronics site within days of each other. You tend to not realize what it is you forgot to buy until after the shipment arrives. In short, we spent a little too much on shipping than we should have. So anyway, all of the equipment is here and I've already made some tests on the GPS with the arduino, and the radios. Thankfully I have access to the electronics equipment at school: oscilloscopes, storage-scopes, meters, etc. I hope to have the tracker finished by spring break, but I have a lot of work to do. I may post a video on the Facebook page of some tests in the weeks to come. In other news, we've decided on a launch date, which will be the weekend of April 18th-21st. Why those dates? Well that's another bit of news for you. Recently, I stumbled upon something called the Global Space Balloon Challenge. It's a worldwide competition for teams to enter who are doing projects just like us. We've decided to enter it, and the launch date is between the 18th and 21st of April. We'll be competing against high school, college, and independent teams from countries all over the world!

Well that's about all I have for now. Remember, go like our Facebook page at facebook.com/nearspaceadventures for the latest news and content. 

Oh yeah, and maybe you could help us out a little and press that shiny "donate" button over there on the right side of the page. Don't worry, it's through Paypal so it's quite secure. So yeah, press the button. I dare you.

Facebook (finally)

Just a quick update to say that we are finally on Facebook! Like our page to receive updates on new blog posts and exclusive media as we endeavor to make a second successful launch. Find it all at: https://www.facebook.com/nearspaceadventures