[time-nuts] Simple AC mains zero-cross detector

Mike Garvey r3m1g4 at verizon.net
Thu Dec 18 17:59:30 EST 2014

There is an interesting article in the Nov/Dec issue of Inside GNSS
describing the robust measurement of "...voltage and current phasors at
widely dispersed locations in a power grid".  A Phase Measurement Unit
measures and time stamps the voltage and current phasors "...thousands of
times per second..." to an accuracy of <1 us using GPS.  The authors discuss
several strategies for dealing with jamming and spoofing of the civil GPS
signals.  It's a good read.

See http://www.insidegnss.com/node/4281 


-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf Of Hal Murray
Sent: Wednesday, December 17, 2014 3:28 AM
To: Discussion of precise time and frequency measurement
Cc: hmurray at megapathdsl.net
Subject: Re: [time-nuts] Simple AC mains zero-cross detector

csteinmetz at yandex.com said:
> That one is not ideal for this task, because (i) its output pulse is 
> symmetrical about the mains zero cross, and (ii) the hysteresis zone  
> is not well characterized and will drift with temperature and input  
> voltage.  So, there is no edge that is well characterized in relation  
> to the AC mains zero cross.

What are you going to do with data from the line accurate to 1 microsecond?

These are my opinions.  I hate spam.

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