Hi there,
Having worked with the folks who operate the power utilities (I designed
protective relaying and recorder electronics for several years), I can
advise that they do take the long-term accuracy of their power
seriously. However, the short-term is not a big concern, and in fact,
they
Dean,
Thank you so much for your detailed and authoritative
note about power utilities.
I am not certain of the rules of operation, or of the way they tweak
things (generator bias?), but could find out from friends and
colleagues, if you wish.
If it wouldn't be too much to ask, yes, I think
Hi folks,
I got this message, and I assume you would find it interesting.
8
Due to the extended life of the GPS satellites, we are now facing the
possibility there will be more than 30 satellites in the constellation. It
is believed this might be a problem in some receivers. Receiver
Does anybody in this group look at power line frequency drift?
Somebody once told me that they tried to get frequency info from the Palo
Alto utilities. When they finally got through to somebody who knew what
was
going on, the answer was We aren't tariffed for that.
Does anybody have a
Tom Van Baak wrote,
If it wouldn't be too much to ask, yes, I think several
of us would be interested in how, and under what rules,
they tweak the frequency.
It helps to have a mechanical understanding of the problem.
By the time you get to the end of this, you should know
why the frequency
Thanks, Roj
The data from the UK grid show the daily cycle of loads
in the 8 day chart. Minimum load is about 4 AM. Back in
the 50's we were told that the time of minimum human
activity was 4:30 AM, so that's when we could expect an
atomic bomb attack.
Too bad they didn't plot the delta time
Does anybody have a URL for the frequency specs? (US or California.)
Already people have said there are no guarantees, but my experience:
instantaneous frequency might go up and down one or two tenths
of a percent for periods of time of minutes to tens of minutes and
sometimes (but not often)
Dean Weiten wrote:
Hi there,
Having worked with the folks who operate the power utilities (I designed
protective relaying and recorder electronics for several years), I can
advise that they do take the long-term accuracy of their power
seriously. However, the short-term is not a big
Dr Bruce Griffiths said,
Some generators are kept continuously spinning and
synchronised to the mains but generating little power.
These spinning reserve generators are necessary to
stabilise the grid against load fluctuations, they can
very quickly supply power when required.
I hope you don't
Bill Hawkins wrote:
Dr Bruce Griffiths said,
Some generators are kept continuously spinning and
synchronised to the mains but generating little power.
These spinning reserve generators are necessary to
stabilise the grid against load fluctuations, they can
very quickly supply power when
Has anyone on the list had an opportunity to work with the SigNav
TM3-02 GPS receiver (http://www.signav.com.au/index_files/PDF_Files/
New_Brochures/SigNav%20TM3-02%20Brochure%20V1.2.pdf)
and test the stability of their sawtooth eliminated 1PPS output?
I am curious how the 1PPS stability
Bill Hawkins said (among other interesting stuff)
Why not use automatic frequency control? Because the controllers
in the different stations would fight each other, because they
are tied together by the synchronous network. In other words,
it is not possible to regulate a stable
Note also that, based on my limited experience, most
commercial mixer implementations use a much faster
beat note: 10, 100 Hz, even 1 kHz. A faster beat note
may help your concern #1 above, and #2 below.
Ulrich,
One thing I forgot to mention earlier -- there is another
advantage in using a
Interesting as the techniques employed may be, the resultant performance
is still inadequate for characterising state of the art oscillators.
The instrument phase noise floor is higher than that specified for
current low noise (but not necessarily low drift) crystal oscillators.
Well, true,
Magnus Danielson wrote:
Hi folks,
I got this message, and I assume you would find it interesting.
8
Due to the extended life of the GPS satellites, we are now facing the
possibility there will be more than 30 satellites in the constellation. It
is believed this might be a problem in some
Some on on this list mentioned a Richard McCorkle's Time Interval Counter.
Is there any place on the web that I can get some more info on this. I
don't want to
buy a HP counter to do comparisons of crystal oscillators. I have to
frequency counters but
they are not really useable for phase
Tom Van Baak wrote:
Interesting as the techniques employed may be, the resultant performance
is still inadequate for characterising state of the art oscillators.
The instrument phase noise floor is higher than that specified for
current low noise (but not necessarily low drift) crystal
Hi Bill,
You can find all the details on the Simple Time Interval Counter at
http://www.piclist.com/techref/member/RHM-SSS-SC4/TIC232.htm.
It was developed as a simple way to get phase data from an OCXO
and a GPS into a computer for analysis at minimal ($20) cost.
Enjoy!
Richard
in the August
18 matches
Mail list logo
