Near Space Project



OzHAB1 is Go for launch

After a long wait, the day has finally come where I hope to have a successful launch of my first ever Arduino based High Altitude Balloon project.

My launch approval has been granted through CASA and my NOTAM has been issued for Wednesday morning 9am / Tue 10pm UTC.


The approval process was a lot easier than I had expected. I ensured that I provided all the information required from the regulations for a light balloon and the rest was easy.

I’m currently camped out at the launch site in Barmedman NSW where it must be at least 30 degrees C, so its going to be a hot night. Not going to make sleep easy when I’m rattling all the things of forgotten to bring through my head.


The predicted flight looks straight forward and as long the transmitters hold out, I should get some good results.

I’ll have a APRS tx on 145.175 , and RTTY on 433Mhz.
As long as I have mobile reception I should be able to upload to  or



Connecting chute and payload

I’ve reached a point where I am now securing the payload to the tie lines running up towards the chute and balloon. I want to have as much of the securing done prior to the launch day so I save time and potential last minute problems.

I have seen some launches where the balloon is tied in line at the top of the chute as well as others where it is tied below. My initial though is that the payload is going to weight as much as the balloon itself. If upon bursting the remnants  weigh the same or maybe slightly more, then the payload, its possible that the balloon will pull the chute upside down preventing it from opening.

Parachute with balloon line clipped in

I have placed a mini carabiner similar to that used to hold your keys onto the line running to the chute. I’m hoping that when the balloon bursts it will fall causing the carabiner to slide down towards the payload leaving the chute clear to open.  I just need to ensure that the chute doesn’t tangle with the balloon line.

Both methods seem to have been successful for other people’s launches but I feel that the 2nd method will allow for a better chance of recovery.

Testing out payload lines

The lines around the payload are  taking shape with some test lines taped to the sides. I still need to load the items into the payload and balance out and finally secure with more tape.


I will be placing the trackers in a separate box, so need to ensure that the antenna doesn’t become tangled or interfered with.

I am also trialing some fishing swivels that have a hook clip at one end. They seem to allow the rope to fit onto the swivel and are smaller then the small carabiners.

Fishing Swivel and Carabiner



I have had to use two of these specific types as the clipped end connects nicely to the rope whilst the eyelet on the swivel would require thinner rope.

payloadI am still working on the balancing of the payload but the below shots give you an indication of what it looks like so far.

Fitting Cameras in payload

Decided to use a Styrofoam Esky (Cooler, some people may call it) to house my payload. The small Esky usually stores up to 6 cans of soft drink so its noeskyt overly large. Its also very easy to cut through to make holes for the camera gear. I still need to work on the final attachment to the parachute as the esky comes pre-fitted with a rope tied lid. I will most likely replace the provided rope with my own and add an additional two points to provide more stability during the flight.


I started by cutting a hole for the Go Pro which will hopefully record a video of the flight. The other small hole is for what I think is the light sensor. I will need to make a few more adjustments to get the hole size right, as the Go Pro has a wide angles lens and I can still see the Esky in the shots.

I have also cut another hole in the bottom of the Esky to allow for a second camera. The 2nd camera is my cheap 1080P camera and will be set to take a still shot over 5 secs.

Camera’s in final positions

I am hoping that if I connect the cameras to an external battery that I will be able to extend the battery life. This seemed to work in my initial tests, but I am currently retesting to ensure I can get at least 3 hours of battery life.
I don’t really want to purchase a Go Pro Back pack battery if I don’t need to.

I will be placing some additional foam around the cameras to keep them in place, but have discovered that having the USB cables attached make it more difficult to get the foam to fit.  More cutting and adjustment needed.

Foam insert to keep things in place

The camera’s seem to be locked in tight and I can shake the payload and they don’t budge.

The Go Pro looks good to go (except for battery life), its more a power-on and hit record,  whilst my other camera seems to revert to some basic setup when I turn it on , so I have to reset everything to how I need it for the  flight. During a recent test, I thought I was recording a still every 5 secs but instead it was videoing, it wouldn’t have been too bad provided the battery life lasted.  So I’ll be researching to see if I can save the config somehow to save time and fiddling at launch.

Tracker 2 Progress with Transmitter

Well, things are starting to heat up here in good old Sydney Town, both weather wise and in the shack. I’ve been playing with the 2nd tracker and attempting to get it transmitting some RTTY, and finally tonight after several nights of learning I finally have it working.20151006_223648

First of all I’m still using the FlexTrack code with a Radiometrix TX2EH but have modified the code slightly to work for my purpose. The code appears to use FSK for a 3v model whilst my transmitter is 5volts. For what ever reason I didn’t have any real success with it. I had to tune my radio to USB to hear any tones, and for some reason I was only getting a single tone.
I wanted to have the ability to decode using a handheld and my handheld doesn’t have SSB, so I looked into the AFSK option. Instead of varying the frequency of the transmitter I generate an audio tone and transmit tha20151006_230925_LLSt instead. Tested the receive with my Yaesu FT-857 and the frequency looks a little off from what I would expect, but this may just need some further tweaking of the code.

Consulting a AFSK tone table for RTTY on the KLOTH.NET website, I chose a 425 Hz shift and selected a 2295 Hz high tone and a 1870 Hz low tone. I then exchanged some lines of code that would normally cause the transmitter to frequency shift with the Arduino tone command. After some mucking around, I finally had some success and was able to successfully decode the RTTY

After setting the correct RTTY decode options in dl-fldigi a big smilefldigi came across my face as I was decoding the output from the tracker. The example screenshot is with the GPS disconnected, but with the GPS connected, the zero’s quickly filled with the GPS coordinates.

I’ve still got some tweaking to do, as I’m not happy with the transmitter, it seems unstable with frequency drift and you can tell from the waterfall image it is a little noisy. Hopefully I just need to tweak the code to get this right.

But at least I’ve managed to get it working, as I can now look at experimenting with other digital modes. I know RTTY is fairly old these days and other protocols do exist, but RTTY just seems simple and if it works from near space, then I’m happy.  Happy to hear from anyone who can suggest any improvements.

Next I want to de-key the transmitter between transmissions so that a receiver can be used to receive commands from the ground. May have to look at a DTMF decoder or something.

Looking at something like thisan Solu DTMF MT8870 Decoder Module for Arduino.

Further progress with GPS on Tracker 2

Connected my GPS up this evening to the Ublox U-center to confirm that everything was in working order. Changed the baud rate to 57600. (maybe someone can confirm if this is wise or not?) and yipee everything seems to be functioning.

I’ve read a a number of forums regarding the Ublox GPS and they advise to set the GPS into flight mode, of which I have done. I found this site useful to connect the GPS with U-center. Ublox GPS – U-center20150930_221843

Found some Arduino code on Git Hub for an RTTY based tracker based on Habduino, called Flextrack . It sounds as though it may work for my purpose if I want to use RTTY for the 2nd tracker. However I’m still awaiting the delivery of my UHF transmitter so only have the GPS working via the code so far.

Connected it all up to my Arduino Nano and I;m already getting the Flextrack GPS debug messages. So far so good..

The Ublox 7M seems to be working much better than the GPS in my primary tracker which is only a 6. Much faster in acquiring a fix.

Really need the transmitter to arrive so I can really start to get into the fun stuff.

GPS Arrived for backup tracker

Just received in the mail a GPS Arduino Module with a Ublox NEO-7M chip which will be built into a 2nd stand alone tracker for the payload.

Ublox 7M
Ublox 7M

The backup tracker is also waiting for its own transmitter and receiver module to enable communications with the payload mid flight.

This GPS will also run the cut down system where I want to enable the termination of the flight if a certain latitude is passed.

Got the iron heated up to add some pins so the experimenting can begin whilst I wait the other bits to arrive.

Don’t let me freeze

The air temperature at higher altitudes tends to be below freezing, thus there is a risk that the batteries in the payload won’t operate effectively. Batteries in cold climates are know to have a higher resistance and will usually become flat very quickly.

I don’t want to risk the chance of my payload loosing power, as it will certainly result in a lost payload.

One solution is to choose batteries that function better in cold climates. According to battery university all batteries are impacted by the cold, however some handle it better than others. Certain NiCad and Lithium Ion Batteries can still operate at -40 Degrees C but at a reduced discharge.

So to attempt to keep the payload at a warmer battery friendly temperature, I am considering some air activated toe warmers, the type you place in your ski boots when in the snow.

 These toe warmers can reach 40 Degrees C, so a couple of them should keep the payload warm when its -40 outside.

I still need to test this functionality to ensure it actually works, and that camera lenses won’t fog, but I;m feeling confident.

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