[time-nuts] Updating the unit of,time: the second.

[Mark Spencer]

Just as a side note..  I have looked at the propagation of DTV pilot carriers (as part of an "over the horizon" VHF radio propagation experiment) and the Doppler shifted carriers due to reflections from air craft were typically detected separately along with the "over the horizon" pilot carrier (which was essentially always present.)  It never occurred to me to look for movement of the transmitter.

Sorry for the bandwidth.

Mark Spencer

mark at alignedsolutions.com
604 762 4099

> On May 27, 2019, at 12:38 PM, Dana Whitlow <k8yumdoober at gmail.com> wrote:
> 
> Well, I once had a nutty idea which was to detect earthquakes by looking
> for the phase
> variation of DTV station pilot carriers due to seismic waves propagating
> around, thereby
> changing the physical distance between transmitter and receiver in a cyclic
> manner
> until the 'quake calmed down.   Doing so would require that the phase
> stability of both
> transmitter and receiver, expressed as length units, be within a fairly
> small fraction of
> an inch.
> 
> I've since figured out that even with a Rb at both ends, this would not
> work out- something
> more like an H-maser would be required.  And one other thing- I had
> completely
> forgotten about Doppler-shifted reflections off aircraft, which often fall
> right in the frequency
> range of seismic waves and persist for durations similar to those of
> earthquakes.  But that's
> what got me interested in time-nuttery.  I still intend to do the
> experiment, just to see what I
> can learn about what other factors might exist which cause propagation
> phase variations.
> 
> Dana
> 
> 
> On Mon, May 27, 2019 at 11:27 AM Bob Albert via time-nuts <
> time-nuts at lists.febo.com> wrote:
> 
>> Well I have enjoyed time and frequency measurement for many years.  I
>> have no equipment (nor do I expect to get any) that can tell the difference
>> between the current second and the proposed standard.  And at one point I
>> asked if there was a limit on the smallest time interval that could be
>> discerned.
>> I do remember being impressed with the Collins gear in the 1950s, and
>> wanting one of those 7 foot racks of time standards made by General Radio,
>> the one with the big clock on top.
>> As the years passed I obtained more and more accurate frequency
>