[time-nuts] Timing on Ethernet
Thomas A. Frank
ka2cdk at cox.net
Sat Aug 4 23:54:53 EDT 2007
Ah, but what if one used the tunnel itself as a waveguide, and
propagated an RF signal down it? Would it then reliably arrive at all
the points, with a known delay?
Since the tunnels are probably at least ten meters wide and tall,
that's a pretty low frequency, which is easy to generate, and not
likely to interfere with any of the equipment.
Interesting use for some surplus 11 meter CB gear...and no wires
Does the theory that applies to say a WR-59 waveguide apply to a large
Tom Frank, KA2CDK
On Aug 4, 2007, at 9:15 PM, Dr Bruce Griffiths wrote:
> Neville Michie wrote:
>> 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
> 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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