Because our autonomous balloon is so high, and has a great antenna, it can repeat or re-transmit any voice communications from the ground. This means that an ambulance or fire truck can talk to headquarters on their little mobile radio, even if they are 100 miles away. That is the subject of the previous post.
Another cool thing that our balloon can do is to provide APRS "hops". APRS radios like ours transmit their GPS coordinates on a regular interval. When a special ground station called an i-gate hears this message, it can put the information on the internet so anyone can see that unit's location. The problem is that if the APRS radio is not near to an i-gate, then no-one knows where it is. Our balloon, though, because of its altitude and antenna, can hear any APRS transmission within about 100 miles. (During our second flight, our longest range transmission was over 130 miles). Not only can the balloon hear it, it can re-transmit it to an i-gate. This is called an APRS "hop". So if the commander at the HQ wants to know at any time where all the rescue teams are, instead of talking to everyone, he or she could just look at a live moving map with all the units displayed. To cover a large area like the island of Puerto Rico, we could launch several balloons that would talk with each other and cover the whole island. Our blog includes more details on APRS and how we built our radio using inexpensive parts. The TNC in our system can be easily configured to provide hops.
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Recent events have highlighted reasons for us to use our autonomous balloon technology for humanitarian purposes.
Here is the way we could use our balloon; in a crisis, we could repeat radio transmissions or make cell coverage when cell phone towers are knocked out. Here are examples of what we mean: Puerto Rico has seen widespread hurricane damage and flooding, and not a single person can communicate whatsoever so coordination is rough. What we could do is send our balloon up with our radio, which can repeat any messages within 100 miles! How do we repeat to a 100 mile radius? Our inexpensive 2 meter hand-talkie radio only transmits at 4 watts, but with our good homemade antenna and lots of altitude, we can communicate with stations very far away. The higher it is, the better the coverage. When we were testing our radio on the ground, we had to be less than a mile away from a ground station to make contact. This is the situation in Puerto Rico... Emergency services cannot talk to each other. Once our balloon was above 2500 feet, our same little radio was talking to stations more than 130 miles away! So in a humanitarian crisis, if we launch our balloon to altitude, then a ground radio can communicate to the balloon because there is direct line of sight. Then our balloon repeats the message to other ground stations. This means that two ground stations can talk to each other over massive distances. Texas had another hurricane attack, and coordinating and communication were also problems, but not as bad because their cell towers survived. This is an example of how things can work better when people can talk to each other. Of course there a many more examples, but I think you get the picture. What would be even better than Emergency services talking on the radio is if we could restore cell phone service. What we do, is we send a $250 balloon into the air with a cell repeater, and it acts as a cell phone tower. Now, people who are trapped can call for help. why is it that anything google makes is great? So here is the flight path in google earth!!! like how when you go left or right it changes strange??? :]
the flight path was wonky because a point STRETCHED INSIDE THE EARTH!!! it took us a while to remove it but now its fixed.. But made the top of the path gone (which is that fork at the top of the path). Also, the stupid temp sensors glitched the arduino!!! (Thanks, Noah) So now the part between the beginning and end is gone... Last time the same thing happened. Anyway, that just about does the flight path!!! ( '_' ) P.S we had over 300 page views this week and half of them looked more than twice!!! Thx so much. We looked at the data path for the first few packets and found we were hitting APRS stations very quickly... The first packet at 12:01:43 was picked up from an altitude of 1148 feet, or 500 feet above ground, by a station 38 miles away. The fourth packet was transmitted at an altitude of 2820 feet, or 2100 feet above ground, and was picked up by a station 132 miles away!! The antenna really did it's job. Packet data in the file below: ![]()
We had a debate on what post we should do next. Either more tracking, or photos. Photos won. Remember how we said "Signing off for the night"? well we lied. There was another thing we had to say about this so called "Operation cornfield". The tracking As you may already know, we have only 3 of the 4 things tracking us inside the box. #1: Arduino. #2: Phone. #3: APRS radio. The phone would transmit if on the ground and every 10 minutes while the APRS would do it every 1 minute when beneath 6,000 feet, and every 4 minutes when ABOVE 6,000 feet. What was really interesting about this, is that the flight path calculator we used, got a lot of things right, except that it under shot a lot of stuff. other then that, it was good. another thing is that the parachute we use when the balloon bursts only starts working when it is about 10,000 - 0 feet it drops like a rock if above.. And i am SERIOUS when i say it drops like a rock. it dropped faster then shrek's popularity/ratings after memes came out. Please note that the cell phone actually blanks out after its above 60,000 feet due to a military restriction. Also its got a little tail on it because we forgot to turn it off. (i blame dad.)
Have you ever had that moment when everything just goes to plan? When you started nervous and ended up as the greatest??? Cause this is one of those moments!!! Ill be honest, i'm happy to be home now, knowing that everything has worked. Anyway, with my perfect intro to this perfect post and perfect flight, let's get started. We almost caught up to our balloon all the way with the porsche dad was testing for ford!!! (the porsche was a lousy hatchback one) we made 2 wrong turns, but without that we could have seen it touchdown!!! From last time we thought we would have loads of time, but we only had an hour and the balloon was - at one point - moving at 50 miles an hour, so we had to get on our feet!!! ANYWAY!!! our radio worked perfectly as planed (PLEASE comment "I tracked" if you, well, tracked it) and our phone transmitted its location when it landed, and our camera took photos, our arduino computer stored temp and gps (i didn't even check :D ) and the 808 may have done video (again, i didn't check) but this was such a big success!!! Here are some photos: There will be more coming!!! - flight crew signing off for the night.
We launched!!! all systems seem to be working, or atleast the radio is!!! Please check out the post below this and do as it says, because you can see where are balloon is real time! Anyway, While we were in the process of launching and filling the balloon, we turned all systems on, and everything seems to be working perfectly... not that our items in the box are not doing their jobs, just that we really overshot the trajectory of the flight path. its not THAT big of a problem, but its still going further then expected. in the post below, you can see that we were targeting "Hoytville". its going further. we found out why: not the wind speed, but rather the amount of helium we put in. We were thinking that probably it would be a good idea to put plenty more helium in then what we thought. this is not the problem though, we actually didn't put in enough. funny. The flight plan calculator may also have messed this up by telling us the balloon would rise faster -- just like last year.
As I am writing this, the balloon made the turn around which is good news because it's now headed west at 71,000 feet. Just in case you want to track the flight while it is happening, like us, here is what you do: You go to a website called "aprs.fi" there is no www. in front of it. In the top right You can put our callsign where it says "Track Callsign" so you can look for our radio. Our callsign is KD8NVZ. It will take you to a map view with a track of our flight, and you can click on any of the locations along the flight to see altitude, voltage, temperature etc. Here is a picture from our radio test tonight: ![]() You can also look at the track of the cellphone. It will probably give it's location at the launch site, then we put it in airplane mode until the end of the flight, when it turns airplane mode off and puts it's location on the website so we can go get the payload. Here is the link, but this will only give you flight path when the flight is over: http://www.greenalp.com/RealtimeTracker/index.php?viewuser=jcrocker It looks like this: Thanks for visiting! Wish us luck tomorrow... We will try to post after we launch with an update, but you can track the flight now too!
Well, we got the APRS radio working tonight, so we should be able to track the balloon in real-time as it flies tomorrow. We tested it with our big antenna and it was cranking out signal. We are very happy. There was a grain of solder shorting out two tracks that we found. We weighed the box with everything in it and it is lighter than we thought. It only weighs 1212g including the parachute and antenna and everything. So we re-did the burst calculations to reach 31000 meters, or 102,000 feet to be sure we make our goal of 100,000 feet. ![]() The flight plan changes with a shorter flight time of just over 3 hours because the balloon rises faster, and a shorter flight. We will now launch from Morenci, probably at the school. ![]() Right now our plan is to launch around 11am so we avoid the clouds that come later in the afternoon, if we can get up that early and get on the road.
Using the CUSF predictor, we plan to launch 4 miles west of Morenci MI at 11am, which should land the payload close to Hoytville Ohio where we landed last year. Farmer Alert!!!
We want to land in the same field...! The weather in Findlay Ohio where we hope to land in a big corn field looks partly cloudy tomorrow and the winds are not too high... All systems go!
(except we got a lot of work to do tonight) We went to do some basic antenna testing tonight to make sure that we wanted to use our center-fed dipole... disaster struck!
We have been testing the APRS radio by itself, but tonight we had the full payload box running including the second GPS receiver connected to the Arduino flight computer. We found that there was interference on the APRS channel that prevented the APRS radio from transmitting our location. We thought at first that someone else must have been transmitting constantly on the frequency, no matter where we drove around to! We cut power to the Arduino flight computer and the interference stopped. We plugged it back in, and whenever we move the radio away from the Arduino the interference stopped, and then when we brought it close the interference started again. (We did this over and over again for 5 minutes outside Livonia Police Department where APRS i-gate K8UNS has a huge 80 foot antenna). This is a huge problem because we cannot send both the APRS radio (real-time GPS tracking) and the Arduino (GPS and temperature recordings for later). We thought up possible solutions: 1. Figure out what the heck the Arduino is doing -- tough. 2. Move the APRS antenna further out of the box -- medium but would delay the launch, perhaps next time... 3. Delete the APRS radio from this next flight -- super easy. 4. Replace the APRS that we slaved over for months with a Spot satellite communicator that dad bought off ebay for $10 -- easy but Dad is unwilling to throw down the $150 for an annual service plan (rule #1 + #2). Next: Dad will look into the Spot service plan and if there's no Dad-worthy cheapo option, then I guess we delete the APRS for the next flight until we can re-do the antenna. We hope to launch this coming Saturday July 15th, if possible. We will need to get some work done, and need good weather too.
Weather looks positive for us to launch near the Michigan-Ohio border on either Saturday or Sunday -- clear skies and light winds. We ran the predictor at: http://predict.habhub.org/ and it shows that if we launch on Saturday from Assumption, Ohio we will drop the payload in the same field as last year!!! We also love the burst predictor at: http://habhub.org/calc/ to figure out helium load and flight times .. check it out! Our to-do list: 1. rig the balloon to the payload and melt all cord connections. 2. buy helium from Matheson Welding. We need at least 120 cubic feet. 3. Re-test the APRS radio with both antennas and decide which one to use... rig the dipole antenna if it is the choice. 4. finish velcro-ing the systems into the payload box. 5. make a launch check-list 6. make a launch-day packing list 7. re-stage all systems; clear the data, load new batteries, etc. This post was Dad -- an exception for this blog. Thanks for all the recent page views. Check back because it will be a busy week. One more thing: on launch day, we will post two links to the blog. One will be to the cell phone tracker so you will be able to see the take off and landing sites when the phone is on the ground and transmitting. The second will be to our call-sign on aprs.fi which will enable you to track the balloon flight in real-time, assuming the radio works! Remember to check here on Saturday if not all week! |
AuthorMalachi and Ezra's page where we build cool stuff and either break it, set fire to it, etc. in the name of science. Archives
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