[time-nuts] GPS antenna in snowy environment (was:, LEA-6T, Software.)

Dan Kemppainen dan at irtelemetrics.com
Fri Aug 29 11:55:48 EDT 2014


Björn and Tom,

Thanks for the links. It helps visualize things a lot! Our snow was
unusually weird last year. It stuck on everything, any stick larger than
a pencil had at least basket ball sized hunks of snow on it. That's
probably a worst case scenario, tho.

Joe,

OK on the study of snow. It's good to know that it doesn't attenuate the
GPS a lot. That's good information to have in the back of my head!

We're just east of Minnesota (Upper Michigan).  The air coming over the
big lake warms up, picks up water and dumps it on us all winter long.
Because of the lake effect we're lots warmer than Minnesota, but a lot
whiter too! :)


The next question that comes to mind, is how much cable is too much
cable from the antenna to GPS? Granted every environment is different,
so lets assume you add 150 ft of cable to gain 30% to 40% more sky view
to the south, is the trade off worth while? Pick a coax, say something
like RG-6 (mismatch and all) or something like LMR-400. Is there a
practical limit? Does temperature changing the length of the cable make
any noticeable difference for a Timing GPS?

Dang it! I'm getting bit this time-nuts bug now!

Dan

On 8/29/2014 10:34 AM, time-nuts-request at febo.com wrote:
> I had to study this issue once.  The question was if we needed to 
> provide antenna heaters in the far North.  Like Minnesota and Alaska.
> 
> Turns out that snow and ice are almost transparent to 1.5 GHz, while a 
> fat seagull perching on the antenna was a problem, so we did the tall 
> cone and let it go at that.
> 
> The only exception to the transparency is salty sea ice, which can 
> accumulate on shipboard equipment.
> 
> Joe Gwinn



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