rom: "Vlad"
To: "Jeremy Nichols"
Cc: "Discussion of precise time and frequency measurement"
Sent: Friday, December 15, 2017 9:41 AM
Subject: Re: [time-nuts] accurate 60 hz reference chips/ckts
My setup is pretty simple indeed. This is 9.830400MHZ OCXO which
clock
Yo All!
Jeremy wrote:
> I'm surprised Vlad is seeing as much as six seconds differential
> but maybe I don't understand the experiment. I've done measurements
> of the line frequency here in California and never seen much
> variation.
I live in Central Oregon. Next to the Pacific Intertie and
Jeremy wrote:
I'm surprised Vlad is seeing as much as six seconds differential but maybe
I don't understand the experiment. I've done measurements of the line
frequency here in California and never seen much variation.
When was the earliest time (year) you started looking seriously at the
off
Hi
It depends a *lot* on just where you are and how the “gird” is managed. Many
years
ago, we figured out that the local power company corrected things between 4 and
5 PM.
It became a habit to fire up WWV and watch them slip seconds one way or the
other. A
ten second delta was not at all unusua
My setup is pretty simple indeed. This is 9.830400MHZ OCXO which
clocking MCU. Then it is Zero-Cross detector which connected to capture
timer.
The MCU counting the intervals between of each zero-cross event and
number of events occurred.
if (htim->Instance == TIM5 && htim->Channel ==
H
I'm surprised Vlad is seeing as much as six seconds differential but maybe
I don't understand the experiment. I've done measurements of the line
frequency here in California and never seen much variation.
Jeremy
On Fri, Dec 15, 2017 at 9:02 AM Vlad wrote:
>
>
> I have one of my project boxes,
I have one of my project boxes, which monitor the main freq. Here is
graph which reflect the time difference between of RTC (based on number
of pulses from OCXO) and the "MAIN TIME" which is based on number of
zero-cross events.
The observation period is 486 hours.
On 2017-12-14 23:13, J
On Thu, Dec 14, 2017 at 10:53 PM, Bob kb8tq wrote:
>
>
> Of course this *assumes* an electronic approach. Given that it’s moving
> pretty slow and you
> only are looking at fractions of a millisecond, one *could* do an electro
> mechanical design …...
>
> Bob
>
> There is interesting background o
Hi
My guess is that the “best design” would likely do a sample at some specific
time of day.
Just when would depend a bit on your local grid and how it is fed and loaded.
There are
definitely “it’s 6 PM and everybody just got home” issues with power line
phase.
Next question wold be how long
t...@leapsecond.com said:
> For GPS and OCXO the choice of time constant is fairly obvious. But the
> ADEV for mains frequency isn't quite as pretty. So I'm not sure several
> hours would work; maybe more like days or weeks? Here's a sample ADEV for
> power line frequency:
Has anybody investigat
On Thu, December 14, 2017 8:39 pm, Tom Van Baak wrote:
> One can determine the appropriate time constant by looking at the ADEV of
> the two clocks
It appears that the appropriate design would use a local oscillator which
is stable to better than 10^-7 at 5 years and approximately 1200 days time
c
-- Original Message - From: "Jim Harman"
> To: "Discussion of precise time and frequency measurement"
>
> Sent: Thursday, December 14, 2017 10:08 PM
> Subject: Re: [time-nuts] accurate 60 hz reference chips/ckts
>
>
>> Since the power line has
the
frequency be 50.000Hz
Alan
G3NYK
- Original Message -
From: "Jim Harman"
To: "Discussion of precise time and frequency measurement"
Sent: Thursday, December 14, 2017 10:08 PM
Subject: Re: [time-nuts] accurate 60 hz reference chips/ckts
Since the power line
Since the power line has the desired long term stability but is poor on the
short term, I wonder if a solution might be to use it as the reference for
a "power line disciplined oscillator."
You would want a filter time constant of several hours in the control loop
to smooth out the variations in t
apollo...@gmail.com said:
> Want to provide an accurate (relatively accurate) 60 hz reference to the
> chip. Some room inside for custom modifications. Does a TCXO or similar
> exist in a small package that provides 60 hz ticks?
I doubt if you will find a TCXO that puts out 60 Hz. But it's
National Semi used to make a chip (MM5369) that was designed specifically
for that task, but it's long out of production. I don't know of any
off-the -shelf 60Hz generators, but it's pretty easy to build one.
Here are a couple of web pages that will generate a 60Hz crystal controlled
signal.
h
Pat,
> They drift a few seconds in the course of a few days, and wander back and
> forth.
Yes, it's normal for AC mains to drift around by a few seconds over a day but
it usually stays roughly on-time over weeks and months. Here's an old example
of monitoring mains time & frequency for 45 da
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