[aprssig] Balloon tracking questions
bruce.coates at sasktel.net
Fri Feb 25 19:13:11 EST 2011
There are at least two great Yahoo balloon groups. Try posting you questions to one or both of these. There are lots of folks that will be glad to help you.
For our SABRE flights we fly two independent trackers, both on 144.390. It doesn't always happen but two GPSs near to each other can occasionally interfere with each other. Also be careful of the path you use so as to avoid unnecessary interference especially in populated areas like California. We have two hops in our APRS path because there's very little APRS traffic here but that would be excessive where you area. Your would probably want zero hops or one at the very most. Also be careful of the transmit power. We run 300 mW and 500 mW and both trackers are heard throughout the flight from 50 to 100 miles away. As far as antennas go, we use a quarter wave radiator made from guitar string with one counterpoise. The other tracker uses a dipole made from coax with the shield pulled back over itself. For our vehicles we just use standard mag mount antennas. A 5/8 wave will give you a bit more range when the payload is on the ground, a 1/4 gives better coverage when it's in the air. Both will have a null straight above the vehicle so you may experience poor reception when you're directly below the payload. Outside the vehicle, a rubber duck might be good enough. Aside from our two redundant trackers, we run two milliwatt beacons on 220 and 440 MHz. We've had more than one equipment failure but we've always had at least one method of tracking function. (Except for SABRE-1. Check out the write-up on our web page)
As far as power goes, Lithium batteries are the only way to go. With reasonable insulation, the temperature inside your payload should remain above freezing.
Bruce - VE5BNC
SABRE - http://ve5aa.dyndns.org/balloon
----- Original Message -----
From: "Ted11" <tedlists at hullar.com>
To: "'TAPR APRS Mailing List'" <aprssig at tapr.org>
Sent: Friday, February 25, 2011 1:44 PM
Subject: [aprssig] Balloon tracking questions
> Hi everyone,
> I've gotten involved with a high-altitude balloon project, and could use
> some advice. An undergraduate atmospheric science group from my university
> (UC Davis, in Davis, California) had its first launch last April. The
> tracking and recovery effort, although successful, was a little touch and
> go, and ultimately relied on GPS data provided by the meteorological
> instrument package. The primary cell-phone based tracking method failed.
> So, this time around, I've offered to implement a better tracking strategy.
> I'm planning to use an APRS based tracker setup. I'm familiar with the
> Byonics and Argent tracker/radio/GPS offerings, and understand the need for
> a high-altitude GPS. What I'm a little less familiar with are best
> practices for power supplies and antennas. I did a few searches (including
> the APRSSIG archive, but didn't come up with a lot of good information, so I
> thought I'd ask the group.
> 1. Is there a dedicated balloon tracking list I should be sending my
> questions to?
> 2. Any recommendations for GPS, radio, and tracker combinations? Any
> particular combinations that do not work well together?
> 3. What is the best approach for power? I'm concerned about the extreme
> low temperatures, especially in light of some of the recent failures I've
> read about.
> 4. What do you recommend for antennas, both on the balloon and on the
> ground? I've got a VX-8DR I will be attaching to a roof mount antenna on
> the tracking vehicle, but wonder if there is a better approach to match
> balloon and receiver antennas.
> Thanks for the help.
> aprssig mailing list
> aprssig at tapr.org
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