Don't forget that there are folks in the building that have been launching balloons since your parents were young ...  they can surely help out with the actual balloon part ...

Peter

On 02/09/10 22:51, Aaron Botnick wrote:

Hi All,

The OUARC has decided to undertake a project to construct an APRS
High-Altitude Balloon, launch, and successfully recover it. Mission
tasks include successful tracking via the APRS network for position,
speed, altitude, and temperature, along with a possible on-board camera
to capture still images at specified intervals. I've pulled the task of
coming up with a basic parts list that is, as yet, incomplete. We are
soliciting opinions and advice on how to proceed and suggestions on
funding sources.

I've spec'd several parts from Argent Data Systems, maker of the
OpenTracker 1+ and OpenTracker2, I own the OT2m and have nothing but
good things to say about it.

I propose use of the OT1+ SMT, which is a smaller version of the OT1+
that includes everything except the on-board temperature sensor and DB9
connectors (the headers are on the board), and also includes voltage
input from 6-28V with a 5V regulator for GPS power. The ability to run
the APRS interface at lower voltages will allow us to use a LiPo battery
pack for power. I've also spec'd a low-power 2m transmitter (SRB
MX146LV), available from Argent Data, is around 500mw and runs on 5V.
For GPS modules, there is a very tiny unit from Trimble that has an
aviation (> 30k ft) mode, but runs at 3.3V. We also have the Duelo and
ADMS GPSs based on the SiRF Star III module running on 5V. We should be
able to get a thermistor and run it on one of the analog inputs (there
are 5 on the OT1+), and calibrate the device before launch for
conversion of the data later. As for a balloon, we'd like to acquire
something akin to the severe weather sounding balloons. The LM335Z
temperature sensor is rated at 10mV per Kelvin, and a minimum
temperature of -55 ˚C, which should take us to nearly 250 mb according
to the std atmospheric profile.

The whole package needs to be under 4 lbs to be legal, from what we've
read. We also need to determine a semi-waterproof box to put the
equipment in, a recovery mechanism (ribbon / parachute), and find an
inexpensive Canon digital camera capable of running the CHDK firmware to
take pictures at specific intervals.

Links for reference and prices...

CHDK - http://chdk.wikia.com/wiki/CHDK

$40 - OT1+ SMT -
http://argentdata.com/products/otplus.html
https://www.argentdata.com/catalog/product_info.php?cPath=22&products_id=64

$69.50 - SRB MX146LV Transmitter -
https://www.argentdata.com/catalog/product_info.php?products_id=134&osCsid=a3d00b3b69a4ffc11c9c99223b0d12be


$60 - Duelo GPS SiRF Star III
https://www.argentdata.com/catalog/product_info.php?cPath=23&products_id=61&osCsid=a3d00b3b69a4ffc11c9c99223b0d12be


$53 - ADS-GM1 GPS SiRF Star III
https://www.argentdata.com/catalog/product_info.php?cPath=23&products_id=85&osCsid=a3d00b3b69a4ffc11c9c99223b0d12be


$49 - Trimble GPS
https://www.argentdata.com/catalog/product_info.php?cPath=23&products_id=95&osCsid=a3d00b3b69a4ffc11c9c99223b0d12be


$7 - 8" 2m BNC Antenna
https://www.argentdata.com/catalog/product_info.php?products_id=130&osCsid=a3d00b3b69a4ffc11c9c99223b0d12be


$0.75 - LM355Z Temperature Sensor
https://www.argentdata.com/catalog/product_info.php?products_id=50&osCsid=a3d00b3b69a4ffc11c9c99223b0d12be


Thanks for looking this over, and any suggestions you can offer. We
certainly aren't the first to do this, a quick google search will show
others, but this is a first for our motley crew.


73,

de Aaron, WX5AB ([log in to unmask])

--
Peter Laws / N5UWY
National Weather Center / Network Operations Center
University of Oklahoma Information Technology
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