[time-nuts] Low cost synchronization

Mike Ciholas mikec at ciholas.com
Thu Aug 18 16:27:32 EDT 2005

On Thu, 18 Aug 2005, Chuck Harris wrote:

> Phase lock the crystal to the 50/60 Hz powerline?  The signal 
> seems to be ubiquitous.

I considered that.  There are many problems:

The person with the device may move from one place to another and 
may pick up anyone of three possible phases of power or different 
utilities (they are sync'ed?).  In this case, it may become hard 
to constantly watch your phase and adjust.  At best, you can make 
short temporal measurements based on stable signals and use that 
to look at you local crystal.

But, on short time scales, the 60Hz wave has poor stability.  It 
is controlled well on longer time scales (witness all the clocks 
using it), but we can't assure a stable environment to measure 
that against.

60Hz is also very low frequency.  I wasn't sure I could pick it 
up reliably despite all my experience getting it when I don't 
want it!

Worth thinking about, though (says the man with a 250KV three 
phase trunk outside his building...)

Mike Ciholas                            (812) 476-2721 x101
CIHOLAS Enterprises                     (812) 476-2881 fax
255 S. Garvin St, Suite B               mikec at ciholas.com
Evansville, IN 47713                    http://www.ciholas.com

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