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In Reply to: RE: get your own atomic clock chip for half that price posted by kh6idf on July 25, 2012 at 06:23:38
Half a microsecond / day!
And suitable for embedded devices / applications.
Now, how does that accuracy / repeatability and precision compare with the range of jitter specs measured on current consumer digital devices?
Is CD or DAC jitter in PPM or ???
Using the broadcast WWV / WWVH signal in a home situation is generally impractical, though I know of the in-home 'atomic clocks' with built in receivers. If you live in the wrong place, using WWV becomes less than practical.
WWV is what? 10KW or maybe 25KW? Even with a good SW receiver I am sometimes not able to get a good, stable signal at any frequency from 5Mhz to 20Mhz. I'm not sure about lower fequencies.
I've even logged WWVH from the Hawaiian islands....You can sometimes hear it during the planned downtime of WWV which still comes from Ft.Collins, Colorado.
Too much is never enough
Follow Ups:
...for typical consumer 'atomic clock' synchronization using a time code. You're unlikely to get it on most general coverage / shortwave receivers as the signal is well below the US AM broadcast band in frequency.
I've never received WWVB...My LW receiver goes to only 150KHz. As it turns out, I've never gotten ANYTHING below the standard AM band.
Antenna length is daunting and normal interferrence wipes out anything that remains. I don't recall trying those frequencies when Southern California had a near-12 hour power lapse last year. At that time, normal SW reception was Epic. and electrically quiet. Too bad I couldn't power my Stereo.
The modules used in 'atomic clocks'....which I guess just update themselves every day (nite, actually, when reception is best) are sometimes removeable....so the real over achiever could use one of THOSE and probably get the same end result or better...as one of those expensive 'local' modules w/built in source.
WWV and WWVH broadcast the encoded time as well as WWVB.....And since it is the LW version which provides the time code, for 'atomic clocks', my objection to WWV / WWVH is out the window.
As a total aside, the US uses ELF or VLF to communicate with subs. The waves will go thru some depth of salt water. The transmitters take up a LOT of space, miles in most cases. Also, due to huge inefficiencies, radiated power is just a small fraction of that needed to run the operation.
Too much is never enough
. The transmitters take up a LOT of space, miles in most cases.
HAARP deals with this.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
I thought the ELF / VLF antenna array was in Michigan?
The Russians have s similar program at a frequency near 60Khz.
HAARP is high frequency stuff.....10Mhz......and sounds weather related.
Too much is never enough
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