Project Horus High altitude balloon project


Chase car tracking

I've written some software to allow our chase cars to post their current positions to the tracker during the flight, as well as the balloon payload.

This means the position of both the balloon & 2 chase cars will be updated in near real time - position updates will be uploaded every 10 seconds. This relies on our chase cars having internet access - we may encounter some areas of no mobile broadband service, though we should have at least GPRS coverage most of the time.

I've included a screenshot of the tracker as I went for a drive to test the chase car tracking software.

Chase car tracking

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Quick update

Did not yet get around to doing a tethered test due to the weather here - it's been in excess of 40 degrees C for the last few days.

Visited Adrian and did some testing of the telemetry & found a few bugs - the most notable being that the temperature sensors were failing once the GPS achieved lock. Reason for this was that the interrupt driven software UART to the GPS was throwing off the delays enforced to give the temperature sensors time to take their readings when data was being received. I've since fixed this, and moved to a more accurate timing method for the RTTY telemetry.

The pressure and humdity sensors have arrived and have been connected. The pressure sensor seems to be working correctly, I need to test the humidity sensor against an environment of known humidity to make sure it's also working.

I've started work on a GUI frontend to track all the balloons sensors. I'll upload screenshots of this soon.

Currently awaiting final CASA approval, launch in the next 2 weeks is looking promising, with good wind conditions. Will finish off the tracking page soon & have a few ground based runs to ensure everything is in working order.

Predicted flight path

Predicted flight path

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Current state of affairs

Haven't had much chance to work on the project or update the blog in the last couple of weeks due to the festive season being in full swing - aiming for a launch in a week or two though, I'll set a tentative date soon.

I was given a Sparkfun voucher for Christmas(thanks Holly! :D ), which will go down a treat. Sparkfun are selling a humidity sensor which I'm ordering for the payload - this simple analogue sensor looks really easy to use, having an almost linear output.

Sparkfuns humidity sensor breakout board

I'm also ordering an MPX4115 pressure sensor from Farnell - a (cheap) absolute pressure sensor with a range from 15kPa to 115kPa. A minimum of 15kPa means that I will only have accurate pressure data upto 45,000 feet, but I don't know of any other sensors which are capable measuring lower pressures in the same price range.

MPX4115 pressure sensor

MPX4115 pressure sensor

I purchased a piezoelectric buzzer to be used as a warning tone when the payload descends below 1 or 2km, and to help us find the payload in case it lands in trees or scrub. This little buzzer can run on anywhere from 1-13v, and draws less than 10mA at 5v. Even on a single AA battery, it's very loud!

Piezoelectric buzzer

Piezoelectric buzzer

My balloons have arrived from Kaymont also. I'm planning on doing a tethered test of telemetry & software this weekend, I'll send an email to everybody who's contacted me regarding tracking. Tethered balloons are bound by maximum altitude restrictions, so range will be limited, but hopefully we should be able to get an idea of how well everything is working.

Kaymont balloons

Kaymont balloons

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Project update

A big thanks to Michael Kubler of Grey Phoenix Productions for his very generous contribution of components, IC's, PIC's and much more which will no doubt come in handy in the build of the project! :D

I have also been in touch with several radio amateurs offering both sound advice, and assistance with tracking of the balloon. Thankyou to all who have contacted me and offered input. :)

I am currently planning to build a small (50-100g) payload comprising of GPS and a radio transmitter to use for radio testing before the real launch - to get an idea of range & performance.

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UKHAS Launches

Just followed the launches of Icarus and Xaben by UKHAS members online. The distributed listener modifications that they've made to fldigi worked amazingly well, the payloads were tracked online flawlessly - much to the credit of jcoxton, rjharrison, fnoble, edmoore & others!

Also got my new Atmega328's, and my Arduino is back from the dead. Haven't yet tried flashing it again.

Exams will be over in a week, soon I can spend some more time building up the payload. :)

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External triggers code

I had a chance to rig up the external trigger on the main camera (the Lumix) this weekend - it didn't go as smoothly as I'd hoped. This camera pretty much kicked my butt - it's usually a good idea to safely discharge the flash capacitor before working inside a camera. Usually you'd do this with a resistor - alternatively, you could forget to do so and accidentally shock yourself half a dozen times. Eventually I de-soldered the capacitor to save myself further pain.

This camera (not surprisingly) was much more intricate and complex than the toy that is the Kodak - it was a bit of work just to reach the shutter button contacts. After eventually getting the right bits off, I decided to test the camera & ensure I was dealing with the right contacts - this went fine, until I touched part of the (metal) casing against the circuit board & smelt smoke.

Much cursing later, I realized I'd blown a fuse - trouble was the size of the fuse - only 1mm or so! I don't have any tiny SMD fuses, much less the skill or tools to solder them, so I bridged the 2 end of the fuse with a drop of solder, which solved the problem.

I eventually got the shutter connected to an external trigger (though this also proved tricky) and put everything back together. There are 4 pins on this trigger - 2 for focus and 2 to release the shutter - though it seems operation on only 2 pins (focus + shutter) is possible.

I've also written more code for the GPS side of things - all the useful data is parsed out of the NMEA sentences, checksums are validated, etc.

Also realized my temperature sensors are only good to -40 degrees C, significantly warmer than the payload will be exposed to. I've ordered 2 DS18B20 sensors capable of reaching -55 degrees to replace them.

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External trigger

I rigged up the Kodak camera to have an external trigger today - so that the Arduino can control it.

The main camera still hasn't arrived, nor has the NTX2 transmitter :( .

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More deliveries

Another visit from the postman today - this time with my ICOM 706 Transceiver! :)

Didn't have much time to play with it, but powered it up and had a quick poke around & whipped up a power cable for it - the seller didn't have the regular power cable, but was good enough to include a suitable plug and pins. My cable still needs fuses, which I'll sort out tomorrow. Transceiver seems to run OK on a 12AH 12V SLA battery which I can put in a backpack to take it mobile when we recover the payload, though unsure what the battery life will be on this battery.

Also got hold of an SD card for the Kodak camera - I bought a 2GB card, but it turns out the camera doesn't support any larger than 1GB. Swapped the card with a friend & the camera seems to be working fine. Movie mode only manages to record ~1 hour of film on the 1GB card, so continuous filming throughout the flight is a no go. Will probably have it capture a minute of video every few minutes.

Here's a fullsize photo snapped by the Kodak, not as bad as I had expected for about $15.

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Welcome to the official project log of Horus! For more information, please check out the about page.

This log is somewhat belated - many components & tools have already been sourced & some design has already been done. I'll keep this updated as the project progresses - at this stage, I am hoping to launch in December, 2009.

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