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<div class="moz-cite-prefix">900gm is good going for all that gear
without getting very specialised, especially with two cameras in
the mix.<br>
<br>
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!! :-).<br>
<br>
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.<br>
<br>
Keep us posted on the balloon, it's a fascinating project...<br>
<br>
Cheers, Chris H.<br>
<br>
On 08/01/13 09:48, André Geldenhuis wrote:<br>
</div>
<blockquote
cite="mid:CAE3AsJDjb_fTFFbS0+b4AKOKS4txJ4hqZ_7t-087oRa8iU8nvw@mail.gmail.com"
type="cite">Hi Chris<br>
<br>
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<br>
<br>
Cheers :)<br>
Andre<br>
<br>
<div class="gmail_quote">On Tue, Jan 8, 2013 at 8:08 AM, Chris
Hellyar <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:chris@trash.co.nz" target="_blank">chris@trash.co.nz</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF">
<div>Hi Andre,<br>
<br>
Can I ask a possibly not relevant question: why only 10mW?<br>
<br>
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.<br>
<br>
Just curious about the design decision as a rapid ascent
balloon is one of my (many) unfinished projects.<br>
<br>
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.<br>
<br>
Cheers, Chris H.
<div>
<div class="h5"><br>
<br>
<br>
<br>
On 07/01/13 23:58, André Geldenhuis wrote:<br>
</div>
</div>
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<div>
<div class="h5">
<blockquote type="cite">Partial success I'm afraid :P<br>
<br>
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.<br>
<br>
<br>
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<br>
<br>
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
:)<br>
<br>
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.<br>
<br>
<br>
I'll let the list know if we get any picures back<br>
<br>
Cheers<br>
Andre<br>
<br>
<br>
<div class="gmail_quote">On Mon, Jan 7, 2013 at 8:51
PM, Mark Atherton <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:markaren1@xtra.co.nz"
target="_blank">markaren1@xtra.co.nz</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">Hi
Andre,<br>
<br>
Looks like it was a sucess, well done.<br>
<br>
From <a moz-do-not-send="true"
href="http://goo.gl/1o6o6" target="_blank">http://goo.gl/1o6o6</a>
password microprize ...<br>
<br>
Launch time close to 10:42, with signal loss
12:51, so just over 2 hrs flight time (?)<br>
<br>
Not obvious what altitude you managed, or I
haven't found the correct button yet.<br>
<br>
Any chance of a quick report here and maybe a
fuller report with photos at the next Tait-meeting
?<br>
<br>
Regards,<br>
<br>
Mark<br>
<br>
<br>
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