It hurts to read this. John K1AE
-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Jim Palfreyman
Sent: Monday, October 17, 2016 9:46 PM
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] Atomic Watch
Well I think there's a mi
"Whereas other clocks fall victim to relativistic effects at high speeds,
cesium clocks do not. The frequency remains the same, and so the time remains
accurate.”
Well, to the wearer, it probably does. :)
It’s ironic they said that given that they flew cesium clocks in the
Hafele–Keating exper
Well I think there's a mistake or two here...
https://www.inverse.com/article/20497-john-patterson-atomic-ce
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Mixers also have the curious phenomenon of non-reciprocity
On 10/17/2016 4:13 PM, Bob Camp wrote:
Hi
Simple answer is yes.
More complex answer gets into things like the noise of the mixer (not just it’s
floor),
the levels of the signals, noise being coherent rather than non-coherent, AM
<->
Hi
Simple answer is yes.
More complex answer gets into things like the noise of the mixer (not just it’s
floor),
the levels of the signals, noise being coherent rather than non-coherent, AM
<-> PM
conversion and on and on ….
Bob
> On Oct 17, 2016, at 4:45 PM, Anders Wallin
> wrote:
>
>
On Mon, 17 Oct 2016 23:45:23 +0300
Anders Wallin wrote:
> Can someone help me with how phase-noise through a mixer is calculated?
Have you had a look at Enrico Rubiola's mixer tutorial[1]?
I think it contains all you need for noise calculation.
Attila Kinali
[1]
http:
Hi group!
Can someone help me with how phase-noise through a mixer is calculated?
Let's say I connect a 1 GHz signal with -80 dBc/Hz PN (wrt. 1GHz carrier)
at some offset to the RF port.
I then connect a 900 MHz signal with also -80dBc/Hz PN (wrt. 900MHz
carrier) at the same offset.
I'm intereste
A lot of the telecom GPSDOs that speak SCPI have no way of running except in a
"position hold" mode. The Trimble Thunderbolt and telecom GPSDOs (like the
NTBW, NTPX, etc) units can run in a dynamic environment... how well they do
that is left as an exercise for the user to determine. They als
Hi
Survey is pretty much a bad thing while in motion :)
Some (but not all) GPS modules allow you to set up in a “mobile / do not
survey” mode. This is one area that the
newer ( = not 1997 era) devices do much better at. It also is something that
SBAS / EGNOS / WAAS may indeed
help you out on.
Speaking for my GPSDOs specifically, you can’t disable the survey mode with the
Venus838 receiver (well, you can, but it requires you to talk to the module
with SkyTraq’s software, which requires disabling the GPSDO’s controller -
possible to do, but annoying). I haven’t attempted to see what it
Erik,
For what it may be worth... I have two DATUM
9390-52054 GPS Frequency and Time Standards. A
few years ago I had to replace the original
Vectron oscillators in one of the units and
eventually in the other one. In my case I used a
McCoy VCXO that's in an oven. This McCoy
oscillator,
On Mon, 17 Oct 2016 07:25:34 -0600
"Cube Central" wrote:
> I had run across this just yesterday:
> https://www.youtube.com/watch?v=zILwgQhjC_Q
>
> He talks about how crystal oscillators are sensitive to movement and changes
> in gravity. An interesting watch!
As usual with EEVblog, there ar
Hi
In addition to TimeNuts, there are actually *are* people who get nutty about
measuring
changes in gravity. That’s a bit different than what he’s talking about in the
video. Local
variations in the earth’s mass cause variations in gravity (think mountains or
similar…).
They also are one of
I had run across this just yesterday:
https://www.youtube.com/watch?v=zILwgQhjC_Q
He talks about how crystal oscillators are sensitive to movement and changes in
gravity. An interesting watch!
-Randal
(at CubeCentral)
-Original Message-
From: time-nuts [mailto
Hi
Is the OCXO in your GPSDO acceleration compensated? If not then the acceleration
involved in your “moving around” will get into the OCXO at around 1x10^-9 / g.
Some
OCXO’s are compensated to the 1x10^-11 / g level. Some low cost crystals are up
around 2x10^-8. Often vibration is an issue as we
Joe,
In T-mode, the location in X, Y and Z is assumed known so those values
is used as constants in producing the T difference between a satellite
and the GPSDO. As you now move your receiver from the original X, Y and
Z those location errors will translate into time errors. The worst of
this
jg...@zianet.com said:
> What about this scenario - the GPSDO has a fixed position on initial
> powerup, but then it is moved periodically or even continuously, without
> updating the GPS coordinates. The distance from the original coordinates
> could be anywhere from close by, to across the state
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