[time-nuts] Galvanic decoupling of GPS antenna

Robert Benward rbenward at verizon.net
Wed Jun 16 17:37:58 EDT 2010


Yuri,
Why don't you get a small GPS and keep it with the antenna, and isolate the 
digital side of the GPS with opto couplers?  Supply power to the GPS, and 
the GPS supplies power to the antenna.  Optically couple the digital side to 
your controller.  The RF transformer you might come across are probably not 
rated for isolation purposes, especially at +/-250V

Bob


----- Original Message ----- 
From: "Yuri Ostry" <yuri at ostry.ru>
To: <time-nuts at febo.com>
Sent: Wednesday, June 16, 2010 5:09 PM
Subject: [time-nuts] Galvanic decoupling of GPS antenna


> Hello,
>
> I'm trying to put gps (for a coarse timing sync and RTC
> auto-setting) to a small controller that must be completely
> galvanically decoupled from outside world. Antenna power must be
> supplied from separate power source (ground potential of isolated part
> of circuit can slowly float up to +/- 250 volts referenced to ground
> of antenna power supply).
>
> First thinked about using some choke to inject power, then DC-blocking
> capacitor around 20-30 pf and then smt 1:1 wideband transformer, but
> looks like Mini-Circuits don't make standard models for frequencies
> over 1200 MHz, their search engine give me some part numbers that looks
> like special order ones, and cannot be found in their catalog.
>
> Is there any chances to get decent performance if I'll simply split
> stripline (both ground and signal traces) by dc-blocking caps? Idea
> looks not very good to me, of course, I suspect that i'll get all
> sorts of interference right to GPS LNA input...
>
> Maybe there is some well proven solution with easily obtainable parts?
>
> -- 
> Sincerely,
> Yuri                          mailto:yuri at ostry.ru
>
>
>
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