[time-nuts] 60Hz extra PPS: got one

Lester Veenstra Lester at veenstras.com
Fri Aug 10 18:13:01 UTC 2012


Software 60Hz PLL


Lester B Veenstra  MØYCM K1YCM W8YCM
lester at veenstras.com

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-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Hal Murray
Sent: 10 August 2012 13:37
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] 60Hz extra PPS: got one


bill at iaxs.net said:
> Hal, do you have a resonant 60 Hz filter in the pickoff?

Not by intent.  It's just a wall-wart transformer and then some resistors to

get the right level.  There are the standard cables (wall wart, RS-232, 
audio, clip leads).  I'm sure there are resonances in there but nothing near

60 Hz.

> Remote-controlled tap changers can do things like that.

Bingo.  Thanks.

Here is a graph with the vertical scale zoomed in on the top of the sine 
peaks so you can see the voltage step.
  http://www.megapathdsl.net/~hmurray/time-nuts/line/2012-Aug-09-a2.png


> I expect you'd rather do things in software, but the mechanical solution
is
> to couple a synchronous motor to a flywheel marked with 60 Hz lines for
> photocell pickup.

Good idea.  Or an old clock motor.  Do they still make motor driven clocks?

The kind with the flag that drops down and turns red on a power loss rather 
than blinking 00:00.


I should be able to do something with a simple L-C.  I'll have to check the 
numbers.



-- 
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