From Chuck Shepherd's News of the weird comes this item:
In July, film director David Lynch announced that he had
formed a foundation to raise $7 billion to fund 8000
Transcendental Meditation practitioners to bring world
peace by creating a unified field of stress-free brain
waves over the
of precise time and frequency measurement
Subject: Re: [time-nuts] Low cost synchronization
Hi Mike,
Sorry for the late reply. You raise an interesting
question and here are some thoughts.
1. Crystal Modeling
Standard 32 kHz crystals won't work. TCXO aren't
good enough either. OCXO are too
Magnus Danielson wrote:
For any solutions that give you stable frequency
only (XO, RF carriers, 60 Hz) you will need a way
to set the initial time and to reset the time when
the batteries fail.
For some countries will 60 Hz or 50 Hz no longer be maintained on 24 h basis,
so it may be
a bad
For some countries will 60 Hz or 50 Hz no longer be maintained on 24 h
basis, so it may be
a bad idea to depend on it.
I keep hearing, on this group, that the powerline is no longer sync'd to
utc, and evidence for
that fact being a lack of motorized wall clocks. Well, clocks that sync
to
Tom Van Baak wrote:
still the powerline. Basically, any appliance, or device that plugs into
the powerline is likely to
use the powerline for its timing function.
-chuck
Correct, my measurements clearly show that
mains power is steered to UTC. See:
- Original Message -
From: Magnus Danielson [EMAIL PROTECTED]
snip
BTW, measuring the 53rd overtone frequency may not give a clear
picture of the
frequency deviations at the base frequency. Overtone spectras
experience quite
a different phase shift from the way it is produced by
Poul-Henning Kamp wrote:
In message [EMAIL PROTECTED], Magnus Danielson writes:
The interesting thing is that they have been seriously thinking
about transmitting UTC and tarriff information on the grid, but it
looks it is cheaper to just use GPRS mobile phones.
Indeed. In Sweden that has
Hi Mike,
Sorry for the late reply. You raise an interesting
question and here are some thoughts.
1. Crystal Modeling
Standard 32 kHz crystals won't work. TCXO aren't
good enough either. OCXO are too power hungry.
A couple of quartz wrist watches are good to 5 or
10 seconds per year. This may
Just as with WWVB receivers, he does not have to have the GPS powered up
very long for and
then only once a week or so to keep the oscillator tuned up. Once a GPS
solution has been
found, the local time and the GPS solution time give a time-difference and
by remembering
the GPS solution time
On Sat, 20 Aug 2005, Tom Van Baak wrote:
1. Crystal Modeling
Standard 32 kHz crystals won't work. TCXO aren't good enough
either. OCXO are too power hungry.
Yup.
A couple of quartz wrist watches are good to 5 or 10 seconds
per year. This may be close enough for your needs.
Yes,
On Sat, 20 Aug 2005, Bill Hawkins wrote:
Perhaps this is a means to coordinate an attack.
Ah, the age of paranoia. Rest assured, the experiment's purpose
is as far from that as possible.
If you look at my requirements (accurate to a few seconds, lasts
more than a year, low cost, built in
Hi Mike:
It may not be possible to get what you are asking for as a stand alone
time keeper but I think could be done by periodically resetting.
Using a radio signal for resetting has problems with the coverage area
and/or power consumption.
Maybe the resetting signal could be an audio
On Sat, 20 Aug 2005, Bill Hawkins wrote:
Perhaps this is a means to coordinate an attack.
And Mike Ciholas replied,
Ah, the age of paranoia. Rest assured, the experiment's purpose
is as far from that as possible.
Well, no, not so much the age of paranoia as the age of extreme
self-interest
Mike - I've spent a fair amount of time looking in to this as part of
my Internet testbed. At the moment, I have about 25 nodes using
EndRun's CDMA time receivers ($1k-ish each), so I've been very
interested in cheaper solutions, for obvious reasons.
I assume that the devices of which
David Andersen wrote:
Local stable crystal: Actually, you could make it more than stable
enough, but it would exceed your power requirements, because you'd
probably fall back to an oven controlled oscillator. There goes your
battery. But why did you try your initial experiments with
A couple of points here.
Yes, a 10MHz oscillator will severely blast the budget - power wise. But
you should remember that 10MHz is also not actually a good frequency for
temperature coefficient of crystals - except for SOME SC cut types.
Generally speaking the zero tempco rollover frequency
On Thu, 18 Aug 2005, David Andersen wrote:
I assume that the devices of which you're speaking are
standalone items? Something like a sensor deployment, possibly
networked? Knowing more about how you actually plan on using
these would help a bit.
Yes, it would. The devices are part of a
Are the subjects all within major metro areas? I wonder if the TV stations
are sending usable time codes in their blanking intervals these days.
-- john, KE5FX
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On Thu, 18 Aug 2005, David Forbes wrote:
The 32K crystal may be usable, but you'd have to put some
effort into the design to get the temp compensation tuned to
the particular crystal, and you'd have to grade the crystals
for tempco in the mfg stage. That might be doable in quantity,
if
On Thu, 18 Aug 2005, Chuck Harris wrote:
Phase lock the crystal to the 50/60 Hz powerline? The signal
seems to be ubiquitous.
I considered that. There are many problems:
The person with the device may move from one place to another and
may pick up anyone of three possible phases of power
On Thu, 18 Aug 2005, buehl wrote:
The 1 Hz difference leads to the problems of 'is it +1 or -1;
I can deal with this with a digital counter. You will always
know if A is ahead of B or not.
Or at zero, there is no output to count.
Yes, this is a problem. Perhaps it is better to make
Phase lock the crystal to the 50/60 Hz powerline? The signal seems
to be ubiquitous.
Not sure if this would work to the level you need.
See:
http://www.leapsecond.com/pages/mains/
/tvb
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- Original Message -
From: Mike Ciholas [EMAIL PROTECTED]
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Sent: Friday, August 19, 2005 7:34 AM
Subject: Re: [time-nuts] Low cost synchronization
Yes, it would. The devices are part of a social experiment
Yes, it would. The devices are part of a social experiment and
are meant to be carried by humans.
Speaking of social experiments.
I thought I had a reasonable idea as to what a GPS 1PPS is used for -
until I read this:
http://home.connection.com/~louis/globalchimes/proposal.htm
Regards,
On Fri, 19 Aug 2005, Geoff wrote:
Speaking of social experiments.
I thought I had a reasonable idea as to what a GPS 1PPS is used
for - until I read this:
http://home.connection.com/~louis/globalchimes/proposal.htm
Interesting. This isn't our application, but it shares many of
the
On Fri, 19 Aug 2005, Poul-Henning Kamp wrote:
2. WWVB Receiver
This is probably the most feasible means.
Yes, I concur for at least the US. A 60KHz will get us US,
something in England, and Japan (decoding software needs to be
different, but not the radio parts). Maybe that's good
From: Mike Ciholas [EMAIL PROTECTED]
Subject: [time-nuts] Low cost synchronization
Date: Thu, 18 Aug 2005 12:29:40 -0500 (CDT)
Message-ID: [EMAIL PROTECTED]
Hi Mike,
4. GPS Time Receiver
This is fantasy land. I don't need the 100ns time reference, all
I need is something good to one
So, does it have to handle leap seconds?
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On Thu, 18 Aug 2005, Bill Hawkins wrote:
So, does it have to handle leap seconds?
Hmnm, interesting question. Obviously if we track WWVB, it can.
The important part is that the units stay synchronized. So if
all of them miss the leap second, that is okay. This would be
the case if we
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