[aprssig] high altitude gps and radios

Scott Miller scott at opentrac.org
Tue Oct 30 10:25:59 CDT 2012

I've been trying to get a straight answer from Unitraq on that.  All 
they'll say is 'above 25k' but I get the impression they don't really 
know.  That's probably a question for Prolific, the chipset vendor - 
Unitraq is the integrator.  I've had very little success talking 
directly to GPS chip vendors in the past, though.  They seem to like to 
talk only to their big partners.

I can say from personal experience that I've sent one up to 113,000' 
with no problem.  We did have reports of some losing lock easily, and I 
sent a batch back to Unitraq and they corrected an unspecified firmware 
bug.  We're now shipping units with that version, but I haven't had a 
chance to fly one yet myself for testing at high altitude.

If someone has access to a GPS satellite simulator I'd be happy to 
provide samples for testing!  Otherwise in the next month or two I'll 
put together a throw-away payload and see what kind of altitude I can get.

Might have to invest in some protective gear and start buying hydrogen - 
I've got maybe 400 ft^3 of helium on hand but it's going to get 
expensive when I have to refill.


On 10/30/2012 8:14 AM, ak209 at lafn.org wrote:
> On Tue, Oct 30, 2012 at 06:17:20AM -0400, Bob Burns W9RXR wrote:
>> Both Argent Data (www.argentdata.com) and Byonics (www.byonics.com)
>> sell GPS receivers rated for use at high altitude.
> Argent sells the GT-320FW High-Altitude GPS Receiver, and it says
> it has a special firmware that allows going over 25k meters, but doesn't
> say how high is the max.  I sent email to support at Argent asking them
> how high it supports, they haven't gotten back to me yet.
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