On 03/01/2013 12:26 PM, Tom Van Baak wrote:
Ok, it´s a relative measurement... now I understand your data. Thank you.
Not sure it's relative measurement. Probably best to call it a time error
measurement, or a phase measurement (in the timekeeping sense, not the 2*pi
sense). Just consider a 6
> Ok, it´s a relative measurement... now I understand your data. Thank you.
Not sure it's relative measurement. Probably best to call it a time error
measurement, or a phase measurement (in the timekeeping sense, not the 2*pi
sense). Just consider a 60 Hz wall clock; the data is how far wall clo
On Thu, Feb 28, 2013 at 6:08 AM, Daniel Mendes wrote:
>
> Thanks for all the comments about this topic. They are much appreciated.
>
> About the difficulty of measuring every cycle with a conventional counter...
> thanks for that info, seems that i´ll have to make my own measurement
> hardware. I
Ok, it´s a relative measurement... now I understand your data. Thank you.
Daniel
Em 28/02/2013 20:03, Tom Van Baak (lab) escreveu:
Yes, correct, sometimes the power line goes faster than 60 Hz in which case the
zero-crossings occur before you "expect them"; so time error can be negative,
on
Yes, correct, sometimes the power line goes faster than 60 Hz in which case the
zero-crossings occur before you "expect them"; so time error can be negative,
on average, as often as it is positive.
You cannot design a PLL that always expects phase error to be unidirectional.
The data I provided
Em 28/02/2013 13:37, Tom Van Baak escreveu:
Daniel,
I've placed two log files for you under http://leapsecond.com/pages/mains/
log1932.dat.gz -- timing of every 60 Hz zero-crossing (1.296 million samples)
log97312.dat.gz -- timing of every 60th zero-crossing (21.6 thousand samples)
Each repres
On 2/28/2013 11:37 AM, time-nuts-requ...@febo.com wrote:
About the difficulty of measuring every cycle with a conventional
counter... thanks for that info, seems that i?ll have to make my own
measurement hardware. I liked the idea of a time stamping counter
it?s very doable in a FPGA:)
At
y 28, 2013 6:08 AM
Subject: Re: [time-nuts] Logging the grid frequency
Thanks for all the comments about this topic. They are much appreciated.
About the difficulty of measuring every cycle with a conventional
counter... thanks for that info, seems that i´ll have to make my own
measurement
Thanks for all the comments about this topic. They are much appreciated.
About the difficulty of measuring every cycle with a conventional
counter... thanks for that info, seems that i´ll have to make my own
measurement hardware. I liked the idea of a time stamping counter
it´s very doabl
By their nature, these "distributed generation" devices operate in current
injection mode. That is, they are synchronized to the line and inject enough
current at whatever voltage the line is at (subject to IEEE 1547 provisions,
e.g., -12% to +10% of nominal) to transfer the power they need to.
On 02/23/13 12:01 PM, John wrote:
All,
If you want a reason for logging the mains frequency, see the following
link to a news item which appeared on a BBC news program a few weeks ago
here in the UK.
http://www.bbc.co.uk/news/science-environment-20629671
There was also a full program about it
definitely have affected a zero crossing detector.
Didier
Sent from my Droid Razr 4G LTE wireless tracker.
-Original Message-
From: David
To: Discussion of precise time and frequency measurement
Sent: Sat, 23 Feb 2013 4:14 PM
Subject: Re: [time-nuts] Logging the grid frequency
is method will not be so
>> sensitive to noise around the zero crossings. It will use the entire
>> waveform.
>>
>> Didier
>>
>> Sent from my Droid Razr 4G LTE wireless tracker.
>>
>> -Original Message-
>> From: Gabs Ricalde
>
l Message-
From: Gabs Ricalde
To: Discussion of precise time and frequency measurement
Sent: Fri, 22 Feb 2013 9:01 PM
Subject: Re: [time-nuts] Logging the grid frequency
Hello,
I also don't have a Picotest or similar equipment but I've done similar
things by using the line input of
--Original Message-
From: Gabs Ricalde
To: Discussion of precise time and frequency measurement
Sent: Fri, 22 Feb 2013 9:01 PM
Subject: Re: [time-nuts] Logging the grid frequency
Hello,
I also don't have a Picotest or similar equipment but I've done similar
things by using the line
All,
If you want a reason for logging the mains frequency, see the following
link to a news item which appeared on a BBC news program a few weeks ago
here in the UK.
http://www.bbc.co.uk/news/science-environment-20629671
There was also a full program about it which you can listen to at the
> So it is not correct to measure one point to a gnat's nose
> hair and call it "the grid frequency."
Bill,
Yes, and this is true for any source of frequency. That's why when we specify
stability the averaging interval is critical; the x-axis of a log-log ADEV plot.
One might look at every cycl
I think you have to ask what is the use that is going to be made of that
number. Do you want to know how well an old synchronous clock will keep time or
do you want to know when there's been an (inductive) phase shift that signifies
the loss of a transmission line? Are you interested in how ph
Friends,
The grid contains a massive amount of inertia in the rotating
synchronous machinery that generates power. The 'springiness'
of the transmission lines allows local noise and even phase
noise that is caused by loads added to or dropped from the
line. Hal Murray (ICBW) had pictures of indivi
Hello,
I also don't have a Picotest or similar equipment but I've done similar
things by using the line input of a soundcard. Multiply the recorded
signal with a 60 Hz quadrature oscillator, apply a low pass filter then
do some analysis on the resulting phasor. The stability of the sound
card osci
Hi
A lot depends on what the real objective is. Is the loop supposed to transfer
all of the 60 Hz bumps and wiggles (wide band loop) or is it supposed to ignore
them (narrow band loop) ? Given that the starting point is 60 Hz wide and
narrow will be relative to that.
Bob
On Feb 22, 2013, at
On Fri, 22 Feb 2013 15:16:37 -0800, "Tom Van Baak"
wrote:
>> There is a lot of noise on the line. I'm not sure if frequency makes sense
>> on a cycle to cycle basis.
>
>Hal, it might make sense since the OP is designing a PLL and wants to get a
>feel for (short-term) frequency excursions. I wo
, but I've not tried hard enough. The HP 5372A is another
possibility.
/tvb
- Original Message -
From: "Bob Camp"
To: "'Discussion of precise time and frequency measurement'"
Sent: Friday, February 22, 2013 5:34 AM
Subject: Re: [time-nuts] Logging t
> There is a lot of noise on the line. I'm not sure if frequency makes sense
> on a cycle to cycle basis.
Hal, it might make sense since the OP is designing a PLL and wants to get a
feel for (short-term) frequency excursions. I would guess the whole point of
his experiment is to quantify this;
On Fri, Feb 22, 2013 at 10:47 AM, Hal Murray wrote:
>
> You can also feed the line into a modem control signal on a PC serial port.
> (USB probably won't work.) The PPS logic from NTP will count cycles and
> record a timestamp on the last one.
Yes RS-232 wants a signal that is about +/- 9 volt
People have measured AC mains period (and hence frequency) with very
simple devices. The best is just an AC plug-in power cube and a diode
to square the sine wave then this is connected directly to a DCD input
on a serial port. The Linix PPS driver will time tage each pulse with
a nanosecond time
dmend...@gmail.com said:
> No, just designing a very wicked PLL and needing statistics of the
> frequency derivative... No generator is involved, it´s mains frequency (but
> you gave me another idea... thanks!).
There is a lot of noise on the line. I'm not sure if frequency makes sense
on a cy
No, just designing a very wicked PLL and needing statistics of the
frequency derivative... No generator is involved, it´s mains frequency
(but you gave me another idea... thanks!).
Daniel
Em 22/02/2013 11:53, Chuck Harris escreveu:
Curiosity makes me wonder why you want to measure cycle-by-
Curiosity makes me wonder why you want to measure cycle-by-cycle
variations in the generator frequency.
Are you looking for cycle swing when the load changes?
Or is it a matter of wanting to because you should be able to?
Which, of course, is a great reason for doing all sorts of things!
-Chuck
and
re-arming.
Bob
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Daniel Mendes
Sent: Friday, February 22, 2013 7:47 AM
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] Logging the grid frequency
Hi, I have
Hi, I have a Picotest U6200A. I´m trying to log the grid frequency
(60Hz) to generate data for my work. I need to get data from every
cycle. I setup their program (it always starts in chinese... very funny)
but seems that it can only log every 100ms. Questions:
1) Is that a limitation of the
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