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])
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