1.. 2.. 3.. Sonde

Ivan VK5HS and I, Danny VK5DW, was out again the morning of Friday May 4th for another hunt of the illusive Radio Sonde. The Sonde was expected to be landing in the Wanbi area near the Karoonda Highway about 60kms South of Loxton.

We were hopeful that Rob’s VK5TRM Auto RX tracking station and Ivan’s VK5HS new Auto RX tracking station would provide reporting into HabHub at relatively low altitude.

20180504 - Sonde Hunt - Mindarie - RFHEAD Prediction

So Ivan being from Renmark picks me up on the way through Loxton. As neither of us have the applicable setup for a chase car we headed out leaving my QTH in Loxton at about 0900 (local) with:

  • Android Tablet
  • Lap Top PC
  • GPS Engine for the Lap Top
  • Mobile Phones
  • 2 x Home Brew Yagi’s (Ivan made his in 30mins)
  • Boefeng Hand Held
  • Icom IC-R10 SSB Receiver
  • a lot of positive thoughts!

As we don’t have the capacity to decode the data from the Sonde direct to the laptop we have to rely on internet services such as HabHub. So here are the problems with relying on internet services.

  1. The Sonde tracking is from fixed ground stations in this case the nearest being VK5TRM station over 55kms away, while VK5HS station is over 85kms away. This results in the last known location and altitude being potentially several hundred metres away and up. This makes the potential landing site less definable.
  2. You need to have mobile phone service to have internet access!

OK so the challenge set we get into Alawoona and pull up to monitor the balloon progress for a bit while we still had internet. With increasing confidence it was going to land around the Wanbi / Mindarie area we moved on to Wanbi pulling over periodically so to hold the mobile phone up out the window to get service and thus updates from HabHub.

20180504 - Sonde Hunt - Mindarie - HabHubAfter a while indications were that we needed to be nearer to Mindarie, indeed a few kms East of Mindarie. So into Mindarie we went then East onto McCabe Rd, Great!!! No internet! Do we rely on Direction Finding (DF) with yagis etc or move back till we find service??? Nope, back to get some internet service, there were simply too much risk of change that we would otherwise miss and render us in the middle of nowhere with respect to the Sonde.

Now we’re back into Mindarie just North of the township by a 100m or so, sitting on a slight rise with mobile phone on the roof of Ivan’s car so we could get a bit of signal for the phone. Ahh that’s better we can monitor what the Sonde is doing.

20180504 - Sonde Hunt - MindarieNow we have service again we watch intently while HabHub predictions show the Sonde landing around Wanbi… are we heading back to Wanbi??? It was about now we got a TXT message over the HF radio from Pete VK5PE saaying it looks like it’s going to land on top of the Wanbi PUB. Do we move or do we not? Nope let’s wait and see for a bit… … … Hmmm it seems to be predicting landing sites closer and closer and closer to us, we’ll site tight for a bit longer.

After a while we found ourselves under the flight path, staying put was the correct call, we were going to be within a km or 2 at this stage. I’m still monitoring HabHub while Ivan is out with his yagi and receiver trying to DF it on its approach. Before long data was showing we were in the hot seat. I jest-fully prompted Ivan to walk West to the train track (dis used) and hold his hands out to catch it.

Next thing you know Ivan asks what directing I thought it was coming in, to confirm his DF skills, then I hear a yell from Ivan… “It’s right there, quick get a camera!” Too late, it’s down! Now we had another issue that in the haste to get a camera, remember the phone is still on the roof, we lost sight of the thing… where is it? OK OK stop laughing!

Right lets see if we can get a bit closer, we chose to drive to where we thought would be closer. So this was another lesson… we weren’t closer!!! Not that we knew that yet.

DannyOk so now we’re out of the car, Ivan with R10 receiver and yagi and I with Boafeng Hand Held Transceiver and yagi, trying to DF the signal. Of course the signal at such close range is quite strong so the signal had to be attenuated somehow. Ivan could use the SSB function and also use the squelch functions. He also used the yagi in horizontal polarisation for further attenuation and ran off the back of the yagi. I used the Boafeng, of course FM only, and progressively de-tuned the frequency to create attenuation, used the yagi in horizontal and off the back. Both methods used by Ivan and myself certainly work well enough for DFing the Sonde.

Well that decision to drive a bit closer didn’t work out that well. We ended up walking about 300m instead of my be 100m from where we watched it come down. Anyway we got it and we were pretty chuffed none the less. All packed up and the Sonde (with string, reflector, balloon remains) recovered we headed home.

20180504_122433Taking the ‘bakery’ lead from Mark VK5QI we called into the Loxton Anzac Crescent Deli for our version, ‘Espresso Coffee Thick Shake’. Liquid gold! A great way to wrap up a really fun hunt.

So the lessons here:

  • Anyone can do this with little equipment
  • Laptop or Tablet with internet access is all that is needed
  • In car and independent tracking capacity is desirable
  • Be patient… Keep yourself best positioned for changing predictions
  • You don’t need expensive kit to DF a Sonde
  • If you see it descending… have your camera ready and don’t look away!!!
  • Don’t always think you can drive a bit closer, especially when you see it land in front of you!

Just a little note and suggestion. Please collect the whole shebang, don’t collect just the Sonde and leave the rest for the farmers, or whoever, to have to deal with.

Thanks for reading,

Danny VK5DW

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