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Tue, 9 Feb 2010 22:51:08 -0600
Aaron Botnick <[log in to unmask]>
Aaron Botnick <[log in to unmask]>
1.0 (Apple Message framework v936)
OU Amateur Radio Club <[log in to unmask]>
cc: Zac Flamig <[log in to unmask]>, Robin Tanamachi <[log in to unmask]>, "Nathan A. Snook" <[log in to unmask]>
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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 -

$69.50 - SRB MX146LV Transmitter -

$60 - Duelo GPS SiRF Star III

$53 - ADS-GM1 GPS SiRF Star III

$49 - Trimble GPS

$7 - 8" 2m BNC Antenna

$0.75 - LM355Z Temperature Sensor

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.


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