Update -
I attempted to look at the analog signal. I looked at the output of the
crystal. With the scope's low-pass filter turned on I was able to see a
very weak sine wave with a period of roughly 15us. It was too weak for any
analysis.
There's a nice set of WWVB 'scope traces here:
http://leapsecond.com/pages/sony-wwvb/
/tvb
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It would be interesting to know what the analogue signal looks like, as
many pieces of electrical and electronic equipment can radiate
significantly on those frequencies.
60 KHz, AM Modulated, low bandwidth. Google will find the details at NIST's
web site.
Likely sources of interference
In the late 70s I took a 6800 based micro I designed for
Sidereal and developed CTU - Chuck's Terminal Unit,
a program that ran an autostart responder on 80 meters.
The computer ran 1000 non maskable interrupts per second.
This powered Baudot send, receive, and distortion measurements.
It also
From: Hal Murray
[]
It would be interesting to know what the analogue signal looks like, as
many pieces of electrical and electronic equipment can radiate
significantly on those frequencies.
60 KHz, AM Modulated, low bandwidth. Google will find the details at
NIST's
web site.
Likely
On Mon, Oct 31, 2011 at 1:54 AM, David J Taylor
david-tay...@blueyonder.co.uk wrote:
Nuts,
I recently picked up a C-Max evaluation kit from SparkFun to see if this
$10 board could be used as a precision timing source. The short answer is
no. The long answer is available at:
Hi David,
Thanks for pointing out the problem with the figures in my webpage. I
have
fixed it. I'm going to attempt to capture the analog signal by probing
the
QOut pin.
The updated images make the effects clearer. It will be interesting to
see the image capture.
Good point about
Nuts,
I recently picked up a C-Max evaluation kit from SparkFun to see if this
$10 board could be used as a precision timing source. The short answer is
no. The long answer is available at:
http://www.fuzzythinking.com/?page_id=29 .
It was a fun experiment and a great excuse to play with test
Hi JP:
Have you tried this at midnight local time?
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.End2PartyGovernment.com/
Justin Pinnix wrote:
Nuts,
I recently picked up a C-Max evaluation kit from SparkFun to see if this
$10 board could be used as a precision timing source. The
Justin,
A while back, I did some crude experiments with the C-Max CME6005 IC which is,
I believe, used in that evaluation module. If memory serves, there were some
rather severe restrictions documented in either the datasheet or an application
note regarding the loading on the TCO/TCON pins.
You can use WWVB for timing but it is not as easy as buying the kit.
First you need a better antenna and then a good location for it that
is away from noisy electronics.then you have to let it disincline
a local clock for a while. It will not be as good as GPS and you may
never get 24 hour
Hi Brent,
I actually saw that warning partway through the experiment. I disconnected
it and didn't get any measurable difference. So, I put it back - it makes
it easier to see what's going on :-)
Based on several suggestions here, I think the next thing I'll try is
capturing actual event
Based on several suggestions here, I think the next thing I'll try is
capturing actual event arrival times. That will allow me to plot a
histogram and let the experiment run all night (and day) to take advantage
of different local times. Plus it gives me an excuse to buy (or build) a
Nuts,
I recently picked up a C-Max evaluation kit from SparkFun to see if this
$10 board could be used as a precision timing source. The short answer
is
no. The long answer is available at:
http://www.fuzzythinking.com/?page_id=29 .
It was a fun experiment and a great excuse to play with
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