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[aprssig] balloon tracker

Gerry Creager n5jxs gerry.creager at tamu.edu
Wed Mar 2 21:27:38 UTC 2005


think in terms of +/- 20% of the operating parameters.

gerry

Curt, WE7U wrote:
> On Wed, 2 Mar 2005, Scott Miller wrote:
> 
> 
>>I think some people have reported GPS receivers freezing up, too.
>>I'm sure some folks here could tell you more about packaging them
>>to keep them warm.
> 
> 
> As I recall most of the GPS'es have a temp sensor in them.  I can
> get a readout for the internal temp on my GPS-II+ by throwing it
> into a special mode.  They have that sensor in order to avoid having
> a crystal oven.  The GPS self-calibrates for temperature, but has to
> be baked/frozen through it's normal ranges in order to gain it's
> data for this calibration.  They do this at manufacture.
> 
> I'm not sure what the extremes are that they cook/freeze a GPS to,
> but I suspect you're going outside those ranges, in which case the
> GPS might not know where it's oscillator is sitting, therefore might
> not be able to find the satellite signals anymore.  I think most of
> them will auto-calibrate in this case, but it takes a long time.  If
> they've never hit those temperatures before and you have a spinning
> payload or other sky-view problems, they might lose lock and not
> regain it until they get back within their normal temp range.
> 
> --
> Curt, WE7U.   APRS Client Comparisons: http://www.eskimo.com/~archer
> "Lotto:    A tax on people who are bad at math." -- unknown
> "Windows:  Microsoft's tax on computer illiterates." -- WE7U
> "The world DOES revolve around me:  I picked the coordinate system!"
> 
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-- 
Gerry Creager -- gerry.creager at tamu.edu
Texas Mesonet -- AATLT, Texas A&M University	
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