One of the coolest projects I have done so-far with my kids is a "near-space" balloon. That's not quite into space itself (100Km+) but so high that the sky looks black and you can start to see the curvature of the earth as the globe rolls away below you.

The Flickr set with the photos from our first launch is here: http://flic.kr/s/aHsjK22nDc

This is a quick-fire slideshow of the photos from the balloon, formatted as a 2.5 frames/sec video. I'm having trouble embedding it so the link is here

In order to take this kind of photo you need to send a camera up to the stratosphere. Ours went 38Km (124,000 feet) straight up. This is easy enough: you attach it to a massive balloon, let it rise until the balloon bursts (due to the v. low pressure at the edge of the atmosphere) and then it will fall back to earth.

In order to see the photos that you have taken, you then need to find the camera afterwards. This is the trick.

Fortunately, at least in the UK and increasingly across Europe, the very helpful guys at the UK High Altitude Society (ukhas.org.uk) have developed a distributed network of trackers who will receive a signal from your balloon, upload the data to a server and plot the position for you on a Google Maps based page (spacenear.us/tracker/).

In order to take advantage of this wonderful network of helpers, we need to build a tracker that will communicate with their equipment. That is what I will outline in this instructable.

There are plenty of rules and regulations regarding what you can fly and which parts of the radio spectrum you can use for various tasks. The approach I will use in this instructable is suitable for the UK under the rules prevailing in 2013. If you live elsewhere or you are doing this significantly after I write this instructable, please check the rules that apply to you. The guys at UKHAS are fantastically helpful.

So - let's build a radio-tracker.

Step 1: Things We Need

The tracker is based upon the Atmel ATMeag328 Microcontroller which forms the heart of many of the popular "Arduino" boards. We are going to make an "Arduino Compatible" board which we can program using the Arduino IDE.

Because the GPS module and SD card both require 3.3v and we have plenty of computing power, we may as well make the whole tracker run on 3v3. That means that we can't clock the '328 up to its full 16MHz but it will run happily at 8MHz on 3v3, and that's plenty for our purposes.

The tracker is designed on a custom PCB which is 5 x 5 cm in size. This means that it can be fabricated on some incredibly cheap PCB fab' sites. The design files for the tracker board and more details on the design are in the later steps.

These are the materials I used for my design. There may well be better options but this worked well for me:


1 x Custom Tracker Board (see next step)
1 x ATMega 328**
1 x 8MHz Crystal (NB not the usual 16MHz)
2 x 22 pf ceramic caps
1 x Radiometrix NTX2 (e.g. from UPU's store)
1 x GPS breakout board with antenna (the board is designed for this one)
1 x SD card breakout board (e-bay)*
1 x board-mount DS1820 temperature sensor*
1 x external DS1820 Temperature sensor (e-bay)*
1 x HoneyWell HSCDANN001BA2A3 board-mount absolute pressure sensor (Mouser)*
1 x tactile switch
3 x 100nf ceramic caps
1 x 100 uf electrolytic cap
1 x MCP1825 ultra-low dropout 3v3 regulator
1K resistors (around 5)
10K resistors (2-3)
4k7 resistors (4-5)
3mm LEDs (0-4 according to preference, different colours)*
Selection of 1% resistors (I used: 47K/6.8K for the battery sensor and 6.8K/10K for the radio driver )
Male header pins (0.1") - some straight, some 90'

Soldering station and solder
Helping hands
Wire strippers

Programming / Debugging Tools:
PC with Arduino IDE installed
USB to UART adaptor (I use a cheap CP2102. FTDI would work too) or program with ISP (see below)

For Bootloading/Programing**:
ISP programmer


Arduino + breadboard or ISP shield

* - These sensors and indicators are not essential to the function of
the board but allow you to send some interesting data and log it for analysis offline.

**You can buy pre-bootloaded chips but they expect a 16MHz crystal. You would likely at least have to correct the timings in the code to make it work on 8MHz. It is certainly preferable to burn an 8MHz bootloader (see later). It's not hard to do.

<p>Is this UK specific, or can this be used in the US as well?</p>
<p>Hi Ugi, I'm also part of the team sending a balloon 25km to celebrate the uni degree anniversary. We're currently trying to get the board and radio receiver talking and running into a few problems. The radio hears the board but when we try to send it to dl-fl digi to get read and parsed out issues arise. Do you see anything that immediately strikes you as out of place? </p><p>Thank you,</p><p>Jaren</p>
<p>Hi Ugi,</p><p>A few of us have been following you're great tutorial to build the tracker board. We are currently trying to upload the code but have gotten the following error message &quot;avrdude: stk500_recv(): programmer is not responding</p><p>avrdude: <br>stk500_getsync() attempt 7 of 10: not in sync: resp=0x00&quot;</p><p>Have you any suggestions on what the problem might be?</p><p>Kind regards,</p><p>Maureen</p>
<p>HI Maureen</p><p>I am assuming that by <br>&quot;code&quot; you are burning the tracker sketch rather than the bootloader <br>(Step 6 rather than Step 3). In either case, can you give me some more <br>info' on how you are set up to program the chip? For example:</p><p>Are<br> you programming it on the tracker board or elsewhere? If elsewhere, <br>how is it set up? If it's on a breadboard, can you post a picture of <br>the layout?</p><p>How are you powering it?</p><p>Do you know that the chip is running (e.g. do you see the blink sketch working when you apply power)?</p><p>What USB to TTL converter are you using? Do you know that it works? Are you confident that you selected the correct COM port?</p><p>Which<br> version of Arduino are you using? Have you used that version of the <br>IDE successfully for burning sketches to &quot;normal&quot; arduino boards?</p><p>Have you burned an 8MHz bootloader to the chip? Do you know that worked?</p><p>Have you selected an appropriate target board corresponding to the bootloader that you burned?</p><p>Without a bunch more information, it could be any of a number of things but my top guesses would be:</p><p>You haven't selected a board that corresponds to the bootloader on the chip.</p><p>You are not pressing &quot;reset&quot; at the correct time when uploading the sketch.</p><p>Let me know as much as you can and I'll do what I can to trouble-shoot for you.</p><p>Ugi</p>
<p>Hi Ugi,</p><p>Thanks so much for your very quick reply! We are sending a balloon up 25km to celebrate the 25th anniversary of our uni degree programme, so your tutorial has been so helpful.</p><p>Yes, we are on step 6, uploading the sketch. </p><p>We skipped step 3 as we were advised by our tutor to buy preloaded chip. We are using bought ISP shield, chip is assembled on board, see attached picture.</p><p>Both red and blue LEDS light up when connected to laptop. I've tried uploading Arduino &quot;blink&quot; sketch and I get the same error.</p><p>I've just re-read your tutorial and see your warning that that pre-bootloaded chips expect a 16MHz crystal so I suspect this is the problem. In what way would we need to adjust the code if this is the problem?</p>
<p>OK - I'm pretty sure that will be the problem. When you hit reset the bootloader kicks in and tries to talk to the PC. Unfortunately, you have a 16MHz bootloader and (I assume) an 8MHz crystal. That means that it won't be working at the correct data-rate. I expect that it's possible to sort this out but it probably involves writing a new board definition, which I don't know how to do.</p><p>Luckily, you only have the chip in a socket. I would suggest that you whip out the chip and follow the instructions at step 3 for writing the 8MHz bootloader. It's really very easy and many many times easier than running a chip at half the speed it is expecting.</p><p>Ugi</p>
<p>Thanks Ugi! Will give that go :)</p>
<p>Hi Ugi,</p><p>Our new chip arrived today so we have gone back to Step 3: Bootloading. We are using the breadboard method and are confident that we've wired it correctly and have selected the correct port. We've also successfully uploaded the ArduinoISP sketch to my Arduino UNO. However at no.10, when we &quot;burn bootloader&quot; we get the following error &quot;avrdude: Error: Could not find USBtiny device (0x2341/0x49)&quot;. Would you have any idea of what the problem might be?</p>
<p>Sounds like you have &quot;Tiny ISP&quot; selected as the programmer rather than &quot;Arduino ISP&quot;. Make sure you select the correct target board (Pro mini 8MHz IIRC) and the select Arduino ISP as the programmer from the IDE.</p><p>Ugi</p>
<p>Thanks Ugi! We've been on spring break so have had a little break from the project. I definitely had the correct programmer selected before, I'm not sure if there was something up with the chip. I bought some new chips and everything uploaded perfectly this time!! Some of the group are testing out the circuit today with the radio receiver, they may have some questions about decoding the data we receive.</p><p>Maureen</p>
<p>PS - you also get a 3-month pro membership for making a project based on one of mine - that's a record! Never given out two in a day before!</p><p>Keep us posted with how you get on with the code - the board is looking great so far.</p><p>Ugi</p>
<p>Thanks Ugi!</p><p>Our new chip arrived today so we have gone back to Step 3: Bootloading. We are using the breadboard method and are confident that we've wired it correctly and have selected the correct port. We've also successfully uploaded the ArduinoISP sketch to my Arduino UNO. However at no.10, when we &quot;burn bootloader&quot; we get the following error &quot;avrdude: Error: Could not find USBtiny device (0x2341/0x49)&quot;. Would you have any idea of what the problem might be?</p>
Build complete (bar the pressure sensor, which may or may not follow). She's all ready for her sketch, which can wait for another day. This is the best instructable ever ☺
FYI: I bought a micro SD Card breakout and the pin configuration was different the the tracker board. Saved some weight using a smaller board, gained it all back with the green wiring needed to connect it ?
<p>Damn it, I'm getting a &quot;stk500_getsync(): not in sync: resp=0x00&quot; as well :-( Going to try it on a linux machine.</p>
Are you remembering to press reset at the right moment? This board does not have auto-reset like the uno does. <br>Hope you work it out! <br>Ugi
Well, I wait for the compilation to finish then press the reset button. Managed to get the code programmed by choosing a different programmer option. One of my LEDs now flashes away nicely. Tested it with a receiver and am getting what looks like RTTY, but seem to have a frequency shift of over 2kHz! I've checked the value of the resistors and they are what they're supposed to be so a bit of investigation is required.
<p>Glad to hear that it's transmitting. To be honest, if you're getting RTTY at 2KHz shift, you're a long way on your way to making a transmitter! </p><p>The NTX module now available is updated somewhat from the one I used, so you may well need to tweak the voltage divider. Consider making R9 larger - say around 4x larger - e.g. 39k or 43k. Hopefully you can get a nice clear transmission pretty easily from there.</p><p>Ugi</p>
<p>PS make sure you have made the links marked sda and scl at the bottom edge of the board in order for the GPS to be able to communicate with the ATMega by i2c. I can't see from the pictures whether those are in.</p><p>Good luck!</p><p>Ugi</p>
<p>Hi Ugi,</p><p>I now have adequate carrier shift (you're right, had to play around with the voltage divider (I'm guessing the reference voltage has changed in this version of the NTX). I'm getting a readable RTTY TX, but with no useful data:</p><p>$$-*/,0,24:59:58,9999.99999,-8888.88888,0,0,99.99,88.88,9999,9.99,82pFFFF*60EE</p><p>$$-*/,0,198:96:72,99.99999,99.99999,0,99,99.99,88.88,9999,7.02,C3p010F*61A6</p><p>CRCs complete ok but as you can see, I'm not even getting a valid callsign (should be DARWIN). I'm going to go through the code and see if I can work out what's going on, but in the meantime I'd appreciate any input from the master :-)</p><p>Many thanks,</p><p>Steve</p>
<p>*UPDATE* Turns out the sketch hadn't loaded properly, but seems to have now. How long did it normally take to get an initial lock on the GPS? I'm now getting my callsign though but still not getting any GPS coordinates or a valid time. It's either not getting a valid lock or there's no comms with the GPS card.</p><p>$$DARWIN,0,198:96:72,99.99999,99.99999,0,99,99.99,88.88,9999,7.19,C3p0119*BF38</p><p>$$DARWIN,0,24:59:58,9999.99999,-8888.88888,0,0,99.99,88.88,9999,9.99,82pFFFF*4201</p>
<p>Assuming that it's out of doors and can see the sky clearly, you should get a lock in a few minutes - I would expect within 5-10 mins at most. It's not like a phone that can use the internet to download up-to-date tables etc, so it does take a few minutes but should not be very long. As a guide, the flight data from the flight detailed in this 'ible took until string 60 to report a full GPS lock. That would be around 6 minutes. It should report time rather faster than that but will take a few mins.</p><p>You can always leave it in the garden &amp; monitor the transmission until you get useful GPS data!</p><p>Your data looks good, in that the data string is all correctly formed. It's difficult to be certain whether you are successfully talking to the GPS. It would certainly be worth running it for a few minutes to see whether it picks up the time at least.</p><p>Post a string after it has sat for a while and I may be able to tell you whether it's communicating with the GPS correctly.</p><p>Cheers</p><p>Ugi</p>
Hi Ugi, <br><br>Thanks for the continued support, much appreciated. I've been doing a bit of work investigating the problems on my board but I'm no closer to making it work. <br><br>1) I ran an I2C scanner on my 328 and got the following :<br>Scanning...<br>I2C device found at address 0x42 !<br>done<br>I've removed the other I2C devices and can confirm that this is the GPS card reporting.<br><br>2) The two temperature sensors don't seem to be reporting on the I2C at all.<br><br>3) There's no change in the output data on the RTTY, even after leaving the board outside for nearly an hour. Is the LED on D13 supposed to illuminate to report GPS lock? I'm sure I read that somewhere :-)<br><br>I'm at the point now where I'm considering ordering a new 328 and populating a new board, just to rule out and track damage etc. It's frustrating, but hopefully I'll get something that works eventually! <br><br>Cheers, <br><br>Steve <br><br>
<p>Hi Steve</p><p>I wouldn't make another at the moment - it sounds about right.</p><p>0x42 is where the GPS should be so if that's answering then you have made a good start.</p><p>The temperature probes use Dallas 1-wire interface not i2c, so they won't show up on the port scan. The Honeywell is on i2c but you aren't using that anyway IIRC.</p><p>It's not D13, but one of the LEDs does report on a GPS lock, but that's assuming the '328 is receiving the data from the GPS correctly - it's if the GPS string reports a lock that you will that light, and if that did then the RTTY string would also be showing GPS data.</p><p>It sounds like the sketch is not talking to the GPS quite correctly. The Ublox on your board is v8 where mine was v6 so there might be subtle differences. Just checking: Did you use the Arduino version indicated in the 'ible and also add the libraries that were attached to the 'ible? There was a specific &quot;wire&quot; library that I used that might or might not make a difference and also a GPS parsing library. </p><p>I will have a look back over my development sketches and see if there is a basic sketch that you could use to validate the GPS and temperature sensors individually.</p><p>The other possible issue is timing - you did use an 8MHz crystal?</p><p>It's just that your board picture appears to show a crystal with &quot;4.00&quot; stamped on it - if you are running a 4MHz crystal then it's not surprising that the sketch is having trouble. However, I would not expect you to be able to load the code anyway if that was the case and you should be getting 25 baud rather than 50.</p><p>Cheers</p><p>Ugi</p>
<p>PS</p><p>This was my first GPS test sketch - it should just request a GPS string from the UBLOX and write it to serial. Try it &amp; see what you see.</p><p>Ugi</p><p>........................</p><p>// Test Ublox</p><p>#include &lt;Wire.h&gt; </p><p>#include &lt;string.h&gt;</p><p>int GPS=0x42;</p><p>void setup(){</p><p> Wire.begin();</p><p> Serial.begin(9600);</p><p>Serial.println(&quot;Starting GPS&quot;); </p><p>}</p><p>void loop(){</p><p> Wire.beginTransmission(GPS);</p><p> Wire.write(253);</p><p> Wire.endTransmission();</p><p> Wire.requestFrom(GPS, 2);</p><p> int avail=(Wire.read());</p><p> Serial.println(avail, DEC);</p><p> avail&lt;&lt;=8;</p><p> byte temp = Wire.read();</p><p> Serial.println(temp, DEC);</p><p> avail+=temp;</p><p> Serial.println(avail);</p><p> //if (avail&gt;99) avail=99;</p><p> Serial.println(avail);</p><p> unsigned long time = millis();</p><p> if(avail){</p><p> for (int i=0; i&lt;avail; i++){</p><p> Wire.requestFrom(GPS,1);</p><p> byte temp=Wire.read();</p><p> while (temp==255){</p><p> Wire.requestFrom(GPS,1);</p><p> temp=Wire.read();</p><p> }</p><p> Serial.print(char(temp));</p><p> }</p><p> }</p><p> Serial.println();Serial.println((millis()-time));Serial.println();</p><p> //delay(1000);</p><p>}</p>
<p>Hi again Ugi,</p><p>Pretty early on I realised I'd accidentally ordered a 4mhz xtal and changed it for an 8mhz one, so I can rule that out :-)</p><p>I'm using Arduino IDE 1.0.3, as per your 'ible recommendation. I have the 3 libraries you included in my 'libraries' folder and they are showing as 'contributed' libraries in the IDE. </p><p>I'm going to send the output of your uBlox test script via PM, because I'm happy to say that it includes my GPS location :-)</p><p>It looks like the GPS module is working, but as you correctly worked out, isn't interfacing with the sketch correctly. I'll continue to investigate :-)</p><p>One step closer to getting a balloon in the air.</p><p>Cheers,</p><p>Steve</p>
<p>Starting the build :-) #veryexcited</p><p>Steve</p>
<p>Nice Board! Which board-house did you use?</p><p>I'll send you a 3-month pro membership by PM - that's the standing award for making something based on one of my projects and posting a photo.</p><p>Just remember to bootload your chip before you solder it down to the board forever!</p><p>Keep us posted with developments - always great to see.</p><p>Ugi</p>
<p>Hey Ugi. I used DirtyPCB.com. Cheap and cheerful but seems good enough for the job at hand. I actually bought a chip with the 8Mhz bootloader already installed. It was just another job I didn't have to do. This is the one I bought <a href="http://www.hobbytronics.co.uk/atmega328-arduino-8mhz" rel="nofollow">http://www.hobbytronics.co.uk/atmega328-arduino-8m...</a> . </p><p>Thanks for the pro membership, much appreciated. I have no doubt that I will be in touch with more questions soon :-)</p><p>Cheers,</p><p>Steve</p>
<p>Great - I didn't know you could buy 8MHz pre-bootloaded chips but the one you linked to looks ideal. I have heard of people using DirtyPCB with good results but never tried it myself yet. I'll have to do so some time.</p><p>Ugi</p>
<p>Hi Ugi,</p><p>I appreciate that this instructable is a couple of years old now, but I wondered if I could ask you a question about your board? You mention that some of the resistors need to be pull up rather than pull down. Can you confirm that only applies to LED 2 and LED 3 please? I'm about to get the board manufactured and want to make these changes before I do.</p><p>This is an amazing instructable by the way. I've wanted to send up a HAB for some time, but your tracker design as well as the explanation is what has given me the motivation to get started. Thank you for that.</p><p>I'm criticalmass on the IRC channel if you ever want to say hello.</p><p>Cheers,</p><p>Steve</p>
<p>Hi Steve - thanks for your positive comments - always a pleasure to write these for people who will have a real interest.</p><p>As far as I recall, the only two issues that I identified with the board were the LEDs on the Serial Rx and Tx lines, which should run via a resistor to VCC rather than GND, plus the pullups on the i2c lines, which I forgot and had to bodge onto the back. As far as I remember, the Eagle files in this 'ible have those issues fixed but I don't have Eagle on this PC so I can't check just now.</p><p>Have a look - if you can't find those then send me another comment of PM and I'll upload some updated Eagle files - I did make corrected versions.</p><p>Good luck! Let me know when you get to launch - would love to track it!</p><p>Ugi</p>
<p>Update:</p><p>If anyone wants Eagle files with the issues of the v1 board fixed, there is a v1.1 in a .zip file in Step 2 which addresses the known issues.</p><p>Ugi</p>
<p>Ugi, you are a top bloke. Thank you :-)</p>
<p>what if it makes collision with airliners ? </p>
You can only fly in the UK if you get permission. That is only given form places and wind directions away from major air corridors. Your flight is also notified to airmen and the maximum weight is quite low.<br><br>If you did actually collide, what would happen is that your payload would be destroyed with very little chance of any damage to the aircraft.
As a commercial pilot I find this terrifying and the suggestion that it would cause little damage to the aircraft arrogant. What if it breaks off a pitot tube, or rosemount or AOA probe? That little tiny chunk of metal getting sucked into the turbine would destroy it. And at altitude that kind of engine damage could be catastrophic.
<p>Do you not read your NOTAMS?</p>
<p>I didn't say that the chance was zero - there is a very good reason that HAB launches need clearance and are made away from air traffic routes with careful consideration of wind direction etc. However, in the event of a collision, the overwhelmingly most likely event is that the line attaching the balloon to the payload will break (it's 30 meters long so it's by far the most likely to take a strike). The breaking strength is controlled to be less than 10kg (IIRC) so the payload would just fall and the balloon pop up like a cork from a bottle.</p><p>I don't dismiss the possibility of causing damage but there is a lot of sky and very little metal even in the payload, which is less than one cubic foot in size. It could happen, without question, but there are many things more likely to cause problems to an plane.</p>
I really hope your big plan for safety isn't really the &quot;big sky, little airplane&quot; theory. If that method was so effective we wouldn't need TCAS, ADS-B, RVSM, not to mention ATC issuing traffic alerts and giving radar vectors to keep airplanes separated. Assuming everyone that reads this is going to head over to their local FSDO or CAA office to get permission to launch a 1 cubic foot box is just stupid; they won't. And while we train for emergencies, a metal box being injested into a motor or through the windscreen (likely killing both pilots) isn't one of them. <br><br>But have your fun and enjoy the pictures.
You are obviously going to find fault no matter what is said. If you are truly a commercial pilot, you would know that weather balloons are launched every day somewhere in the U.S. and I'm sure the UK. As he said many times, clearance is required. Just as with weather ballons, they can give you a launch window that puts it in the air when no traffic is in the area. The sky is not filled with aircraft. There are FAR more areas NOT in flight paths than are. He didn't say go launch ntext to an airport. Get over your self. I'm sure we are all impressed that you can fly a plane. <br><br>I haven't flown in a few years, since I became disabled, but getting my pilots license was one of the easiest things I have done in my life. It's not that ddifficult to fly, yes there are dangers out there when flying. However, I would in no way be concerned for this one. I got my license while in the Air Force and they launched weather ballons form a pad daily, M-F and still flew F-117a, F-4s, T-38 and German Tornados every day with no problems. We flew small aircraft at lower altitudes daily also, mainly Cessnas. Guess what..still no problem with the weather ballons. They just notified us when they were launching and we held take offs till it was clear. Not that hard.
<p>whining whining whining, just don't crash into my house...chukle.</p><p>That same thinking could have saved the DOdo bird or stopped blloms of nasty water plants into other ecosystems causing untold milliions (billions?) of damage. Then ther is Monsanto's death corn, they apparently are allowed to own the maize plant genome, even if in the process it wipes away millions of years of evolution...</p><p>bah humbug I say,</p><p>However, as a person who lives near very busy airports this whole things asks the question HAVE WE LOST OUR MINDS?!</p><p>So sometimes the sky IS falling or maybe one day a plane FALLS OUT OF IT!</p><p>oopsies</p>
<p>and of course with no doubt the whole project is so great and amazing. if i got free time i really urge to experience such project as well. </p>
<p>thank you . but i imagine if the jet engines of plane swallow it, a disaster would happen. no matter if its too small and lightweight. </p><p>the small birds in airports can kill any jet engine by sucking into it. i know the chance is very very small. but just asking. </p>
<p>Could you clarify - is this using Ham Radio APRS for the downlink, or is there some OTHER HAB tracking network?</p>
<p>No,it uses RTTY to send GPS data strings and you will need to download and install DlFldigi to use the tracking map.</p><p>1- <a href="https://ukhas.org.uk/projects:dl-fldigi" rel="nofollow"> https://ukhas.org.uk/projects:dl-fldigi</a></p><p>2- <a href="http://tracker.habhub.org/" rel="nofollow"> http://tracker.habhub.org/</a></p><p>But after you build the system and get it running,go here and setup your payload as to show up on the map once your signal is received (Genpayload)</p><p><a href="http://habhub.org/" rel="nofollow">http://habhub.org/</a></p><p><a href="http://habitat.habhub.org/" rel="nofollow">http://habitat.habhub.org/</a></p><p>Do you live in the USA?</p><p>Jim,N2NXZ</p><p><br></p>
<p>Sorry,it uses the 70cm USA ham radio band 434.650 mhz USB mode.</p>
<p>did you get any gps data above 60,000 feet ? because most gps receivers have an inbuild limit above which they stop (even the ones that say they don't do ..)</p>
<p>Yes - we got full GPS data all the way up to 38km (124,000 feet). The trick is to use a Ublox GPS and set it to &quot;flight mode&quot;. They operate arbitrarily high if you do. You are right, however, the choice of GPS is critical in making this project work. I have noted that in the materials section so hopefully anyone following this will chose appropriately.</p><p>Cheers</p><p>Ugi</p>
One of the best Instructables I have seen. Don't let the complainers bring it down. I have a pilots license too, and was never scared of weather ballons that were launched daily. I sure would not fear this. You clearing it with your local Aviation Authority, and getting clear it through them is more than enough of a safeguard. Keep up the incredible work, I would love to see more of your videos. Have you done more lunches with this platform?

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