[time-nuts] Timing on Ethernet

Dr Bruce Griffiths bruce.griffiths at xtra.co.nz
Sat Aug 4 21:15:24 EDT 2007

Neville Michie wrote:
> Hi,
>   Low frequencies penetrate the ground to some depth.
> However, propagation may vary seasonally as groundwater  
> concentrations change.
> cheers, Neville michie

Even without the seasonal variations in propagation, propagation through 
the rock etc wont be sufficiently uniform to allow simple calibration 
(at the nanosecond level) which rather defeats the purpose of the 
system. The equipment required to characterise the propagation delay 
variations would itself be suitable for implementing the time 
distribution system without the central transmitter.


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