[chbot] Sundays balloon-adventure, report please

Tue Jan 8 08:25:00 GMT 2013

900gm is good going for all that gear without getting very specialised, 
especially with two cameras in the mix.

Without digging out all my olds notes my weight budget was 750gm and the 
3W TX which was the guts of a miniature handheld was about 80gm, so 80x 
the weight of your TX!! :-).

I was only planning one camera but at the time I was having problems 
finding a tracker/GPS that would work at high altitude and something 
else shiny caught my eye...  I've still got the bits in a box 
somewhere.  Might resurrect it one day, but not this year, already got a 
pile of things on this year.

Keep us posted on the balloon, it's a fascinating project...

Cheers, Chris H.

On 08/01/13 09:48, André Geldenhuis wrote:
> Hi Chris
>
> Sounds like a cool project :)  The reason we went with 10mW was that 
> the transmitter costs about $5 and weighs about 1 gram.  Our entire 
> payload including 2 cameras, spot tracker, electronics, batteries for 
> 5hours + and insulation etc only came to 900 grams and I reckon we can 
> reduce the weight some more.  10mW also saves on battery weight.  We 
> also don't really need a faster data rate unless we want to transmit 
> video, which we have considered doing. Obviously our 4 baud data rate 
> wouldn't be up to that :P
>
> Cheers :)
> Andre
>
> On Tue, Jan 8, 2013 at 8:08 AM, Chris Hellyar <chris at trash.co.nz 
> <mailto:chris at trash.co.nz>> wrote:
>
>     Hi Andre,
>
>     Can I ask a possibly not relevant question: why only 10mW?
>
>     There is unlicensed spectrum in the PRS band for telemetry, or you
>     could get a ham involved and run licensed in the 70cm band
>     (Although not that frequency, that's in the repeater uplink
>     section of the band) .  Both options would let you run a higher
>     bandwidth downlink.
>
>     Just curious about the design decision as a rapid ascent balloon
>     is one of my (many) unfinished projects.
>
>     I made the payload container a couple of years ago and got as far
>     as making the camera controller and researching GPS's. My cunning
>     plan was to launch to time the burst with an ISS overhead pass and
>     relay telemetry off the APRS digipeater on board.  It was my main
>     motivation to getting my amateur license at the time, although now
>     I've got the DX bug and that's a whole other bowl of cornies.
>
>     Cheers, Chris H.
>
>
>
>
>     On 07/01/13 23:58, André Geldenhuis wrote:
>>     Partial success I'm afraid :P
>>
>>     The spot tracker stopped above 60k feet which we expected but I
>>     had hoped it would start working once below that again.  It
>>     appears not for whatever reason.     We also had a 10mW radio on
>>     board the balloon transmitting location, altitude and temperature
>>     which the recovery team managed to track all the way out to 80km
>>     with good decoding except when the balloon was low on the
>>     horizon.  The last GPS fix was at 3436m at a composite position
>>     of -44.04174, -173.04946.  The position is composite as the last
>>     two messages only contained one of latitude and longitude due to
>>     signal breakup.   It puts the payload out to sea south of akaroa
>>     harbour.
>>
>>
>>     The balloon ascended much slower than anticipated and we are not
>>     sure why yet, we are still going though the data to try and
>>     figure out what happened.  The slow assent was the reason the
>>     balloon went out to sea, it took much longer to reach its burst
>>     altitude.  Next time we will have cut downs :P
>>
>>     We are hoping it washes up and someone finds it and returns it to
>>     us. The electronics will be wreaked but the two camera SD cards
>>     and data logger SD cards might still be ok and it would be nice
>>     to see the pictures :)
>>
>>     We got about 80% of the objectives for the flight though and we
>>     planned to iterate all the electronics and replace the spot with
>>     a spot 2 which has a ublox GPS unit so will work above 60k
>>     feet.   We will fly the next iteration soonish.
>>
>>
>>     I'll let the list know if we get any picures back
>>
>>     Cheers
>>     Andre
>>
>>
>>     On Mon, Jan 7, 2013 at 8:51 PM, Mark Atherton
>>     <markaren1 at xtra.co.nz <mailto:markaren1 at xtra.co.nz>> wrote:
>>
>>         Hi Andre,
>>
>>         Looks like it was a sucess, well done.
>>
>>         From http://goo.gl/1o6o6 password microprize ...
>>
>>         Launch time close to 10:42, with signal loss 12:51, so just
>>         over 2 hrs flight time (?)
>>
>>         Not obvious what altitude you managed, or I haven't found the
>>         correct button yet.
>>
>>         Any chance of a quick report here and maybe a fuller report
>>         with photos at the next Tait-meeting ?
>>
>>         Regards,
>>
>>         Mark
>>
>>
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>>
>>

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