As usual, it pays to do ones due diligence before purchasing components; and the Spot Messenger is no exception.

The Spot Messenger will provide a means of locating the HAB while it is below 6500 metres. This will allow us to locate the payload…which would be close to impossible with the GPS because LOS issues might stop us from getting radio reception when it is closing in on the surface of Earth. There is however a potential problem with the GEN3 version of Spot Messenger. It has a feature to power down the Spot Messenger if there has been no activity for 1hr. With a flight duration of 2 hours, it is possible that the Spot Messenger might turn off before it is retrieved! Certainly not ideal. So I am considering purchasing the previous version of the Spot Messenger.

Did an extremely successful radio test on the 4th of May from Port Douglas to Buchans Point. The distance between these two locations is 35km. With the help of my wonderful neighbour we were able to :-

• Confirm that the radio link at 1Watt over 35 km works extremely well, even with HAB in the least optimal orientation
• Was able to transmit an image perfectly over the 35km link without any problems at the x-modem layer.
• Was able to get the distance between the two locations (using my mobile GPS co-ordinates and the GPS co-ordinates of the HAB)
• The cut-down mechanism was initiated and burnt through the rubberband a little
• Confirmed that the Groundstation new battery configuration is working well.

The great thing about this test is that the Fresnel zone was 65% which means in the real launch, we would expect even better radio transmission results. There is no shadow of doubt that the link distance (as per rfd900 specs) of 40km is reliable and that the max link distance of 50km is probably easily achievable.

I see no reason to continue on with other aspects of the project.

My Parachutes and Balloons have arrived!

I have purchased:-

• 1 x 800G balloon
• 2 x 350G Ballons

I got these all from the UK.

Below a peek at one of them. I haven’t taken it out because I don’t want to damage the balloon.

 

The problem

I have had issues with the BeagleBone Black turning off after a period of operation. The exact reason I’m not too sure. The rest of the electronics seemed to be on, but I admit I did not check to see if the Sync light remained on the Radio modem.

Some investigations revealed that the BBB PSU voltage was at times dropping down to as far as 4.75 volts. I am pretty sure that the BeagleBone Black has an operating voltage from 4.75 to 5.25 volts. This I suspect is the culprit.

This issue started happening after I pushed the radio up to 30dbi. i.e. the battery has to provide even more power, which I suspect is leaving the BBB with less juice.

I was also concerned now that the BBB battery life, was a lot less than needed for a few good hours of trekking, following the balloon. I decided that an overhaul was required. I did not however, want to go back to two Pb/Acid Gel batteries. Each ways about 750grams, and the two is just too much of a burden.

 

The Solution

I decided that I would need to remove the Linear Voltage Regulator and batteries.

I initially thought I might be able to use the Switch Mode PSU that was used to power the RFD900 modem, but discovered it is producing 5.3 volts out and the BBB has some protection in it to not turn on. So this didn’t work.

Components of the final solution were:-

• A 3S LiPo battery – higher voltage and amperage
• Build and install a Switch Mode PSU

The 3S has a voltage of 11.1 volts (though is more when fully charged). Minimum voltage is 9 volts. This works well because the Switch Mode PSU needs input voltage of ~8 volts or more.

The 3S battery weighs 250grams, which is a lot more than the 75 grams the other batteries weighed, but is considerably less than the Pb/Acid batteries.

Below are some pictures of the result of all this work.