Make a High-Altitude Balloon Tracker (Arduino)

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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 below you.

The Flickr set with the photos from our first launch is here:

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 ( 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 (

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.

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dubbaluga3 months ago

Hi Ugifer and thank you very much for your detailed explanation! I have also spent some time on preparing my first space flight but due to a few other projects it has been postponed.

From what I have learned it seems to be the most difficult to track a flying balloon due to the big distance. Could you please let me know how you did the real tracking or your balloon? Were there any special devices such as a "Gattling Antenna" or a dedicated receiver unit involved or just the parts that were mentioned in the provided link (

Ugifer (author)  dubbaluga3 months ago

Hi dubbaluga - thanks for your interest.

All I used for my flight was an SDR dongle and a mag-mount antenna attached to the car. However there are really two separate types of tracking:

Firstly, there is tracking the balloon for the bulk of its flight. If you are organised then you don't need to worry about this part. If you use a tracker like the one I describe here that is compatible with the UKHAS receivers, load a flight document and tell them when you are flying (& what frequency etc) then there are dozens, probably hundreds now, of radio amateurs and balloon enthusiasts who will track your flight for you. Some of them have very fancy tracking antennas and receiving equipment that will be able to receive the signal from your balloon from a very long distance and in essentially any conditions. However, these can only track your balloon when they can "see" it, which means that near to the ground they will tend to lose your signal as hills and buildings come in between.

The part where you need to be involved is when the balloon is near the ground. If it's your flight then you will want to track it for the first few thousand meters as it rises. You will also want to get near to the predicted landing point once it bursts so that you can pick up tracking near the ground when the fixed trackers lose it. For that you need a portable setup and a car. I found that a laptop, an SDR dongle and a mag-monut was absolutely fine for that. I picked up the signal after landing and pinpointed the landing point to within a bout 3 meters. Because you are close at that point, very high quality equipment should not be needed. I did have a small Yagi directional antenna but I didn't need it so it never got used.


dubbaluga Ugifer3 months ago

Hi Ugi,

thanks for your reply! That's something I didn't think off: just using the SDR dongle for testing the tracker myself and letting others do the dirty job. ;-) However, I have to find out whether there are people who can track balloons in Austria (my country of origin).

Once I talked to a person who is familiar with flying RC equipment and the Austrian law. He told me that officially one would have to register such a high altitude balloon flight. This would result in a certain time frame reserved for the flight. On the other hand, there is a lot of bureaucracy involved and just letting the balloon go into the air would most probably not cause much trouble. Air traffic control could not locate the balloon using a radar as it would simply disappear in background noise and in the unlikely event of a plain hitting the balloon it would be either smashed or vaporized depending on the location where it hits the plain.

Ugifer (author)  dubbaluga3 months ago

Hi - I tried to respond yesterday. Don't know why it's not showing.

There is at least one receiver in Vienna. I expect that if you contacted the guys at UKHAS and found out who it was in Vienna, they could probably arrange for more receivers in Austria for your launch.

We did request Aviation Authority clearance, as you need to in the UK. I'm afraid I don't know anything about the rules in Austria but the guy in Vienna who traks ballons may know more.



cazpian2 months ago

Fantastic project, top notch instructable. Who did you use to fabricate your PCB and how much did it cost?

Ugifer (author)  cazpian1 month ago
Thanks cazpian - sorry for slow reply. I'm on vacation just now. I used Itead studio. Because the board is only 5 x 5 cm it cost less than £10 including postage for 10 copies. I used slightly thinner than normal boards for weight. I think it was 1.0 mm. If you need then fast then it's more expensive because you have to pay for courier delivery.

Let me know if you make a project based on this - or if I can help at all.

waymond913 months ago

This is awesome!
I've been looking for a tutorial like this for a while!

I have never used the radiometrix modules before, but they seem like a good solution.

What did you use for an antenna for transmitting back to the SDR?

What documentation did you find regarding the NTX2 module?

Ugifer (author)  waymond913 months ago

Hi Waymond - thanks for your comment.

The version I used has now been superseded by the NTX2B but lots of information on that and how to use it is available from UPU's web site here:

The datasheet for the NTX2 is here:

It is usual to use a quarter-wave ground-plane antenna, which I made from a length of 50 Ohm coax, with the braiding stripped away and soldered to a ground-plane made from copper tape on the bottom of my box a 164mm element made from the core of the coax extends below the ground-plane. The board is designed to allow direct soldering of the coax.

In the picture in the last step you can see the box I used. The drinking-straw you see supports the quarter-wave element while the little extensions on the corners expand the ground plane to a full quarter-wave in each of four directions.


halamka3 months ago

Why Arduino and microsoft? Why not Commodore with BASIC? (new commodore?) 0000 1101 is Return. 0000 1101 a BASIC program statement into into a memory line. Then type RUN.

Ugifer (author)  halamka3 months ago

I don't understand your comment I'm afraid.

I don't think Arduino it related to Microsoft - it's an independent Open Source development environment. Yes, you can run their IDE in Windows but also on a Mac or Linux box. The great thing about it is that it's a quick and easy way to program a microcontroller.

I was using BASIC on my BBC micro 30 years ago and it still runs, but it's a little heavy to send up in a balloon! Seriously thou', you could do all of this with a Pic writing in BASIC, and there may well be a BASIC compiler for the ATMeag328. I just don't know of one. I had the skills to do this with a '328 and Arduino. Others might well have preferred other systems but I don't have enough experience with those yet. You could use whatever system you preferred.


halamka Ugifer3 months ago
OK. This is where I am at designing a BASIC computer. 0000 1101 is ascii for RETURN. When return is pressed while writing a BASIC computer program, all the characters are then stored in a memory matrix reserved for programs. So , specifically, a flow chart for sorting program line numbers is run through. As on ATARI 2600 BASIC card the entire microprocessor program should be limited to about 1500 or so lines of binary code. JPEG or something similar would be written by other people. The small GB memory cards are JPEG (video compression matrix manipulation) format. The memory cards for PCs are secretly coded. The disc drives are fairly secret. Possibly made secret by Paul ALLEN of microsoft. The area of the us where these computers are built is san jose, not los angeles. Los angeles was where FORTRAN computers were built. FORTRAN is from the 1960's and 1970's. FORTRAN computers are more complex to build. I took apart some boards from what I think were FORTRAN computers. Many , many data busses and address busses.
amccarty53 months ago

Do you know if this tracker would work in the U.S. and what kind of camera did you use the could stand the pressure of going up that high

Ugifer (author)  amccarty53 months ago

As far as I can gather, nearly all digital cameras work fine. As long as it's in an insulated box (the blue foam box you see in the last step) it should be fine. Although the pressure is very low (8 mBar at max height in our case) as long as the camera isn't perfectly sealed it should be fine.

Light and compact is good because you don't want a heavy payload. Also using normal AA batteries is ideal because disposable lithium cells are considered more reliable than rechargeable LiPolys (although the latter do seem to work). Don't use normal alkaline batteries. They just stop working at low temperature. A Canon camera allows you to use the Canon Hackers Development Kit ( which is a good way to set your camera to take a still photo every few seconds etc.

As for the US, I don't know at all whether this transmitter would be legal. It depends upon spectrum allocation which is different in the US. Even if it is, I suspect there is not quite the same density of receivers in the US. However, you don't need many people to receive. One fixed station and one roving receiver might well be enough. My impression is that you need a amateur radio license to launch in the US. US launchers often use the APRS network which you cannot legally use in the UK.

Good luck launching!


Ugifer (author) 3 months ago

Wow! Thanks guys - and thanks to everyone who voted for us.

The girls will be chuffed to have a prize - not that I'm excited at all myself, you understand ;-) !

Thanks again.


halamka3 months ago

Why Arduino and microsoft? Why not Commodore with BASIC? (new commodore?) 0000 1101 is Return. 0000 1101 a BASIC program statement into into a memory line. Then type RUN.

Lloydy213 months ago

Great intractable! I really do like the design of your custom board and the detail you put into the instructable! Made my own radio tracker similar to your own, I opted with using the GSM network as a backup GPS system if anything fails, plus it doubles by providing a internet uplink so I can view images and atmospheric data. I am however having a bit of trouble downloading the Edge files, would you be able to provide an mirror link or maybe a .zip with the files.

Look forward to seeing what you create next! :D

Ugifer (author)  Lloydy213 months ago

Hi Lloydy21

Thanks for your comment - interesting to hear from another HABer.

I did have a sort-of GSM backup in that the payload also carried an android phone that I could text and would text-back GPS coordinates. However, because the GPS doesn't expect to go so high, it takes about 20 minutes to recover once you get back to the ground - by that time we had already found the payload!

How high could you go before you lost GSM reception? I have heard that it drops off very fast with height.

I've added a second .zip file with the Eagles files inside. Let me know if that still causes problems.


lux4x43 months ago

Wonderful.... no words!! Only enjoy!!!

Ugifer (author)  lux4x43 months ago

Thank you for your comment - glad you enjoyed it. It was fun to do.

kisa723 months ago


Ugifer (author)  kisa723 months ago

Thank you!

jrd2103 months ago

Great Instructable BTW.

Ugifer (author)  jrd2103 months ago

Thank you! Looking forward to hearing about your project - if you do get clearance to launch then please come back and post a link to the photos etc. I never grow tired of seeing this type of thing!


This is the BEST project I've ever seen on instractable, I ALWAYS wanted to make a project like this but the problem is that I don't have boards electronics arduino or any resources like this near me. During the video amazing shots I've seen. and the moment of POP:
photo-2014-06-19, 10:11 PM.jpg

You, stop limiting your creativity! ;-) do it!

Ugifer (author)  • The Inventor •4 months ago

Thank you for your enthusiastic comment! Yes. I liked that shot too.


jrd2103 months ago

A jet would maybe go out of its way to pop this, out of boredom. They test far more challenging things on the engines than these!

Ugifer (author)  jrd2103 months ago

They are clearly not keen on having these in high air-traffic areas, but I do agree that they pose very little hazard give how light they are.

jrd210 Ugifer3 months ago
Yea I think it is just the usual bureaucrat worrying and legal concerns, but I spoke with an airline pilot about our project here to launch one next spring and he mentioned that the new engines literally inhale large birds and spin them off. However we will need radar reflection and full ATC contact etc to launch in Canada.
AJMansfield3 months ago

What recovery mechanism stuff did you use for this, anyway? I can see you encased it all in polyethylene foam, so I would imagine the package is meant for reuse. Was that the only measure you took to reduce damage upon landing?

Ugifer (author)  AJMansfield3 months ago

It comes down on a parachute so falling velocity at ground level is down to about 4 m/s. The foam box is enough to cushion the rest of the fall. Nothing of mine was damaged and often even the boxes can be re-used.


fixfireleo3 months ago

i'm surprised there arent rules against these balloons. if lots of people were launching them, it would be a danger to aircraft. heck, even a single balloon could end up crossing paths with a jet at just the right time and bring it down.

Ugifer (author)  fixfireleo3 months ago

There sort-of are. Anything above 2m in any dimension you need aviation authority clearance (in the UK at least). They will only give you that if you're not forecast to go through any busy air-traffic areas and they put out a notice to airmen to look out for your balloon. In any case it's only light and the most likely thing to happen is just that the cord breaks. It's very unlikely that it would bring anything down.

daemonic3 months ago

Brilliant 'ible, and perfect timing, as i was planning on doing something very similar myself. A couple of questions if i may;

- Did you consider using any of the arduino camera modules (although it seems they need a stable image source)
- What size balloon did you use and how much helium was required?
- Did you cater for any kind of water landing, or was it launch and hope?

Thanks in advance :)

Ugifer (author)  daemonic3 months ago


I didn't look into the Arduino cameras but between the tinyGPS library and the SDFat, there's not a lot of SRAM left for other functions. You could write a much more streamlined GPS parser but I wanted to use something that was pre-validated first time.

I used a 1200g balloon. I takes 1 shade over 3 cubic meters of helium. There are calculators that will tell you how much you need. Have a look at the site.

There are landing predictors so you have a fair idea that it won't land in the sea. If you hit a lake or pond then you just have to hope you can reach it - it's all packed in a polystyrene box for insulation so it won't sink!


SupportBuild4 months ago
Looks very interesting... I might try it!
Ugifer (author)  SupportBuild3 months ago


Really worth trying - the photos are amazing and it's vey interesting to see the temperature change at the tropopause & the drop in pressure as you rise etc.

bergerab4 months ago

Wow. Your pictures/video looks incredible. Awesome project!

Ugifer (author)  bergerab4 months ago

Thank you!

I was really happy with the result & the kids thought they were amazing too!


simplebotics4 months ago
Yes! I was going to use a Spot but I may try this.
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