Dave,
I don't mean to be 'picky' but doing a web search for "Allen
Variances" yielded "Allan", so who is right? (yeah, techs like me
tend to be that way, fun intended)
Mike C. Sand Mtn GA
On 10/8/2024 1:13 PM, W0LEV wrote:
toggle quoted message
Show quoted text
Yes,
in those days we were flying Cs clocks even on commercial
flights.? Fun days.? In the lab I was doing Allen Variances
between Cs and Rb.? We were finally convinced with all the
flights that we had to include corrections for relativity.? As
a physicist, I was elated.
Dave
- W?LEV
We had to do that here at the University of Illinois,
too. Back in the early 70's we were doing some ionospheric
propagation studies along with the University of Houston.
We flew two cesium clocks to NBS in Fort Collins CO. They
sent one to us and one to the University of Houston. I was
involved in it because I was studying radio science in
grad school.
Zack W9SZ
Back 'in-the-day' I had to carry (transport) the
'flying clock' from Northwest to White-House (no not
that wh house) to establish the exact 'phase' error
for the ROTHR (Relocatable Over The Horizon Radar).
Why? Yeah, that's another kettle of fish to digest.
Bottom line, it had to do with the 'error' distance
between the transmitter site at wh-house and our
receiver site at NW. If you stuck your periscope out
of the water 1000+ miles away and were traveling just
over 5mph, (knots) well let's just say you now became
a 'target' of interest. Yeah, Dave, then came GPS and
the gee-dunk trips were over.
Mike C. Sand Mtn GA
On 10/5/2024 12:48 PM, W0LEV wrote:
Yes.?
mHz is needed to "compete" in the FMTs.? However,
we should use correct abbreviations for the
units.?
Having
once been professionally involved in precision
timekeeping in the early days of GPS, I well
appreciate error bars in the 10^-14 Hz (in the
lab, only).? Of course, once on orbit, we had to
correct for relativity.? Now we take GPS for
granted.?
Dave
- W?LEV
Dave
- W?LEV
We all like to poke fun about this but if you ever
participate in the FMT you actually do need
milliHertz precision to get into the "green box".
On Fri, 4 Oct 2024 15:12:53 +0000
"W0LEV via "
<davearea51a=[email protected]>
wrote:
> QUOTE:? 200 mhz.
>
> 200 milliHertz?? That's the realm of
earthquakes and subsonics!? Possibly
> you mean 200 MHz, MegaHertz.
>
> Dave - W?LEV
--
73
-Jim
NU0C
--
--
Mike C.