Hi Bob,
On 11/21/18 6:43 PM, Bob kb8tq wrote:
> Hi
>
> Gravity is not the only thing you need to “standardize” if you are building a
> Cs clock from scratch
> in your basement. Magnetic field also quickly gets its nasty fingers into
> things as well. There are other
> environmental impacts, eve
On Tue, 20 Nov 2018 15:30:54 -0800
"Tom Van Baak" wrote:
> How hard would it be to use a hands-off SDR to produce a 5 MHz WWV phase
> data point every second?
Fairly easy. If you go for one of the RTLSDR dongles, you will
have to do the direct-sampling-mod[1], as the tuner chips do not
go this
On Wed 2018-11-21T20:01:18-0800 Tom Van Baak hath writ:
> Right. It's not obvious to me either. I've been looking some time
> for the right book, article, or web page to hand out when people ask
> that question. The same goes for a rotating planet made of foam vs.
> water vs. diamond question.
Jim Lux wrote:
> I'm not sure I understand why the slowing due to spin happens to exactly
> match the speedup from altitude.
Right. It's not obvious to me either. I've been looking some time for the right
book, article, or web page to hand out when people ask that question. The same
goes for a
On Wed 2018-11-21T09:18:58-0800 jimlux hath writ:
> I'm not sure I understand why the slowing due to spin happens to exactly
> match the speedup from altitude.
>
> The spheroidness of the Earth is, indeed, mostly due to the rotation, but
> that would be related to the overall material properties an
Hi
> On Nov 21, 2018, at 12:12 PM, Tom Van Baak wrote:
>
> Donald E. Pauly, WB0KVV wrote:
>> Ft Collins is at 5,003 ft and clocks there run fast by 1.663·10^-13.
>> (g/c^2)/meter) compared to sea level. How did you correct for
>> altitude on yours? I presume that frequency is defined at sea le
You might be thinking that because the earth spins, clocks on the equator run
slower due to SR. But remember the earth is not a sphere, but an oblate
spheroid. So clocks on the equator are also farther from the center of the
earth and thus run faster due to GR. The two effects neatly cancel
Tom Holmes wrote: "If the Earth were homogeneous then g would drop by 1/r^2
outside and 1/r inside the surface. "
This is incorrect. If the earth were homogeneous then g would indeed drop as
1/r^2 outside but would go as r inside. Thus it drops to 0 at the centre as
well as at infinity.
John P
_
Donald E. Pauly, WB0KVV wrote:
> Ft Collins is at 5,003 ft and clocks there run fast by 1.663·10^-13.
> (g/c^2)/meter) compared to sea level. How did you correct for
> altitude on yours? I presume that frequency is defined at sea level
> but I don't know that.
Yes. Standard time & frequency is d
Thanks Steve and Tom for helping me sort that out. Much appreciated.
Tom Holmes, N8ZM
-Original Message-
From: time-nuts On Behalf Of Tom Van Baak
Sent: Wednesday, November 21, 2018 10:49 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] WWV Doppler
On Tue 2018-11-20T19:02:16-0500 Tom Holmes hath writ:
> So if the SI second is specified at sea level, and we know from
> Einstein and TVB's work that going up a mountain changes a clock's
> period, how would the second be affected at the center of the Earth (
> ignore thermal problems, this is a c
A few years ago I did some measurements of WWV Doppler shift, measured by a 0.1
Hz resolution you get in an HP 3586C selective voltmeter. It's not quite a
phase record but does show the significant shifts that occur.
See https://www.febo.com/pages/hf_stability/
John
On Nov 20, 2018, 6:44
vity
on atomic clocks?
Tom Holmes, N8ZM
-Original Message-
From: time-nuts On Behalf Of Tom Van Baak
Sent: Tuesday, November 20, 2018 6:31 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] WWV Doppler Shift
> That was the first time that I had seen
Hi
Having looked at WWV with a Carrier -> BFO -> audio card approach (and a radio
locked to an Rb standard …) you have dig a bit to find a situation that is
beyond a tenth of a ppm. If you average over minutes or tens of minutes (which
is exactly what you do with WWVB) the only time you get pas
> That was the first time that I had seen an xy plot of WWV versus a
> stable crystal oscillator. It is even worse than I thought. I had to
> look up FRK to see that it is a rubidium standard. I talked to Jim
> Maxton the chief engineer of WWVB many times around 1995.
An xy cycle of WWV is jus
That was the first time that I had seen an xy plot of WWV versus a
stable crystal oscillator. It is even worse than I thought. I had to
look up FRK to see that it is a rubidium standard. I talked to Jim
Maxton the chief engineer of WWVB many times around 1995. At the time
I was in Gila Bend 80
On 11/20/18 1:54 AM, ew via time-nuts wrote:
Starting 1970 I used a modified Tracor 599H on WWVB with excellent results. It
had a mechanical counter with 100 nsec, resolution. Noisy but perfect. Yes you
have to take Ionosphere sunrise and sunset in to consideration and the hourly
shift, but b
Starting 1970 I used a modified Tracor 599H on WWVB with excellent results. It
had a mechanical counter with 100 nsec, resolution. Noisy but perfect. Yes you
have to take Ionosphere sunrise and sunset in to consideration and the hourly
shift, but being a very early riser 4AM because of Europe
HF propagation of WWV or WWVH is horrible compared to VLF propagation
of WWVB at 60 kc. In this video the 5 mc WWV signal from Ft Collins,
Colorado is being received in New Jersey. It was compared against a
stable 5mc crystal source. You can see a shift of a few cycles per
second over a few seco
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