Updates:

As I have had a fair bit of interest with the upcoming weather balloon experiment, I have decided to add this page of updates so that you all know how I am progressing.

Update 1.       30/03/05    

 I have had heaps of interest in the upcoming balloon flight 2. Thank you all for your emails and suggestions. The future setup is now looking like this:

Instead of the mobile phone, I will use a UHF radio from Jaycar DC1040. Many say that 0.5W will be enough but I'd rather go for this one which is 1.5W output. Yes, I am still doubtful that even this radio will have enough range but slowly I am being convinced otherwise.

DTMF tones to send position data over the UHF radio. Just like previous setup.

Two rechargeable lithium ion batteries to power the entire system.

Hydrogen gas instead of helium. It's flammable but has a significant amount of extra lift. I expect chances of ignition to be quite unlikely, but extra precautions and full protective gear will be worn by those that are filling the balloon.

Launch date has been set for Sunday the 1st of May. Let me know if you wish to help out or just come along. Email me: philippawlowski at hotmail dotcom.

Required Parts List:

I have found a suitable camera (Japanese made Nikon with auto advance), and have a supplier of hydrogen. Just waiting on delivery of UHF radios to start range testing. Still researching directional antennas and the possibility of a separate beacon on a different frequency as a backup for when the balloon lands.

Update 2.       20/04/05    

 UHF radios came the other day as did the camera. Just waiting on the hydrogen gas and lithium ion cell charger coming from the US. Should start range testing soon.  Also, I have built a UHF directional Yagi antenna as per Stan Swan's Feb. Silicon Chip article. Also, been talking to a radio finding (fox hunting) group that looks like they can supply a separate simple radio beacon and help out with tracking it on the day. This will be a good backup if the UHF radio and GPS etc fails to work.  There is still heaps to do over the next three weeks. Will keep you posted.

Update 3.       15/05/05    

The radio finding (fox hunting) beacon group are definitely in. All parts have been assembled, and all is ready to go.... but wait,... no launch.........

Due to problems with communications with CASA, I have had to move the launch back 2 weeks. The new launch date is Saturday the 28th May. I had some problems in tracking down the right person to talk to regarding the launch and after numerous phone calls, CASA replied and basically said they needed more time to notify the appropriate people. That sounds strange, as for the last launch I organised, the conversation was little more than a "yep that should be fine" sort of thing. While I was tempted to release the balloon without CASA approval this morning, I thought better and halted the launch till appropriate approval is granted.

A few questions have been asked about the format of the DTMF tones that will be sent on the day so I'll try to explain as best I can:

 The microprocessor sends the Latitude, Longitude, then altitude in metres. Just plain old DTMF. The altitude may have some extra digits in it as the serial string between my DTMF encoder and the GPS changes length over 999M. I could probably work around this in my DTMF encoder software, but I have no way of testing it fully at altitude before launch so prefer to just dump the whole lot into DTMF and let the eye on the ground decipher it. The human brain is much better at problem solving than a pic any way.

In terms of software to pick up DTMF tones, I have successfully used True TTY on windows XP but there is no shortage of other DTMF software packages for other platforms. There is a 30 day trial period if you want to have a play with it.

The DTMF tones are sent slowly enough to read out one by one. 

Although DTMF tones are designed to be noise immune, I have found that the True TTY software to not be as good as my DTMF decoder IC. But even the decoder IC struggles in what I consider to still be a reasonable signal from the transmitter. That's worrying to say the least.

As I have a couple of weeks to spare, I am working on some more code that will beep out the signal so that a human ear can decipher it. Will let you know how that goes. Also having a look at whether it is possible for the Picaxe to send Hellschreiber tones. So far it seems it just isn't fast enough to be reliable. Hellschreiber encoded messages are brilliant at noise immunity. Even in the harshest environment, the tones are decoded in such a way that the human eye does the decoding, so any interpretation is done by a human rather than a machine.

Also, for this update, some piccies of payload 2 are in the new page of this site for launch 2.

As the UHF radio can interfere with the operation of the GPS, the construction of this payload has been chosen to be a flat long sheet of polystyrene. The GPS is at one end and the UHF set at the other. See this page for details.

Update 4.       29/05/05    

Thanks to all that came along to the launch, and all that tracked the payload. This one was quite a success. See the new balloon launch 2 page for full details of launch and recovery. 

Update 5.       30/09/05    

Payload 1 has been recovered 6 months after launch. Details here.

Thanks for reading and cheers,
Philip Pawlowski