[time-nuts] Low cost synchronization

[Chuck Harris]

Mike Ciholas wrote:
> Hi,
> 
> I have a challenging research project to build thousands, perhaps 
> millions, of devices that maintain mutual synchronization.  The 
> devices need to be low cost (under $20 retail, $8 manufacturing), 
> small in size (key chain fob), and low power (operate at least 18 
> months on a battery).  Synchronization ideally needs to be within 
> a second or two over a year but there is some leeway to trade 
> cost for performance here up to perhaps 10 seconds of variation 
> per year.  Ideally, the device works anywhere in the world but we 
> may have to limit it to North America.
> 
> 1. Crystal Modeling

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

-Chuck