A Morsel of Information about Chip-Scale Atomic Technology

Thread: A Morsel of Information about Chip-Scale Atomic Technology

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    A Morsel of Information about Chip-Scale Atomic Technology

    I got interested in some of the activities of the Atomic Devices and Instrumentation Group at NIST, as they have performed some pretty impressive miniaturizations on certain atomic instruments they've been researching, including, evidently, working chip scale atomic clocks. So I sent an email to John Kitching, who, I believe, heads up that research group asking about new developments and whether the miniaturization work might at some point get us to a chip scale atomic wristwatch. Here is his reply for anyone who's interested:
    ____________________________________________

    "Thanks for your inquiry. It is very unlikely that the chip-scale atomic technology will reach a point where it could be used in a wristwatch in the near future. The problem is not so much with the size of the instrument but with the power requirements. The existing generation of chip-scale clocks run on ~ 100 mW of power. This would have to be reduced to below 100 microW to make it possible to run it for any length of time on a wristwatch battery. I'm not quite sure why one would want to put one in a wristwatch anyway, other than for marketing...

    Regards,

    John"
    _____________________________________________

    John's last sentence would seem to suggest that he hasn't heard of the uber-geeks on this forum....
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    Re: A Morsel of Information about Chip-Scale Atomic Technology

    While it is too much power when run continuously, it could be viable as an intermittent check on the main oscillator. If one were to wake up the CSAC for a few milliseconds every week as a rate check, it would essentially remove crystal-oscillator aging from the error budget (replaced by the much lower rubidium aging).

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    Re: A Morsel of Information about Chip-Scale Atomic Technology

    Quote Originally Posted by pmonta View Post
    While it is too much power when run continuously, it could be viable as an intermittent check on the main oscillator. If one were to wake up the CSAC for a few milliseconds every week as a rate check, it would essentially remove crystal-oscillator aging from the error budget (replaced by the much lower rubidium aging).
    Every week would not help that much, but every 1-8 minutes could replace current TC ... still the power surge would be important

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    Re: A Morsel of Information about Chip-Scale Atomic Technology

    Truly superb accuracy could be achieved by combining well known time-tested methods that are readily available:
    - 4.19MHz crystal
    - digital thermocompensation
    - digital calibration
    - 3V long lasting (at least for 5 years) lithium batteries

    Any watch featuring the above would perform (accuracy-wise) significantly better than any watch so far in the history. We do not need Chip-Scale Atomic Technology to enjoy better than ever wristwatch accuracy.

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    Re: A Morsel of Information about Chip-Scale Atomic Technology

    That is true, but there seems little impulse by the industry to improve on the current TC technology.
    When I read about it, the CSAC where expected to make it into cell phones first. I would not mind a solar powered CSAC in a wristwatch.

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    Re: A Morsel of Information about Chip-Scale Atomic Technology

    Quote Originally Posted by ppaulusz View Post
    Truly superb accuracy could be achieved by combining well known time-tested methods that are readily available:
    - 4.19MHz crystal
    - digital thermocompensation
    - digital calibration
    - 3V long lasting (at least for 5 years) lithium batteries

    Any watch featuring the above would perform (accuracy-wise) significantly better than any watch so far in the history.
    Yes, I agree. And combining those four features seems so doable with current knowledge and instrumentation. Do you think we'll see such a watch?
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    Re: A Morsel of Information about Chip-Scale Atomic Technology

    Quote Originally Posted by pmonta View Post
    While it is too much power when run continuously, it could be viable as an intermittent check on the main oscillator. If one were to wake up the CSAC for a few milliseconds every week as a rate check, it would essentially remove crystal-oscillator aging from the error budget (replaced by the much lower rubidium aging).
    That's a thought. So the CSAC component would act as a corrective, in the same manner as radio-control technology, to perhaps a non TC quartz movement. With a decent quartz crystal that might give ± 10 sec./month accuracy uncorrected, having a very brief correction via the CSAC module every two days, for example, would keep the movement within less than ± 1 sec. accuracy at all times.
    Last edited by South Pender; March 25th, 2010 at 18:01.
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    Re: A Morsel of Information about Chip-Scale Atomic Technology

    Quote Originally Posted by South Pender View Post
    Yes, I agree. And combining those four features seems so doable with current knowledge and instrumentation. Do you think we'll see such a watch?
    I don't think we will ever see such a watch...... only in our dreams...

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    Re: A Morsel of Information about Chip-Scale Atomic Technology

    It appears that this group, the Atomic Devices and Instrumentation Group at NIST, has produced an atomic clock that runs on a single AA battery:

    http://tf.nist.gov/timefreq/ofm/smallclock/CSAC.html
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    Re: A Morsel of Information about Chip-Scale Atomic Technology

    Quote Originally Posted by Catalin View Post
    Every week would not help that much, but every 1-8 minutes could replace current TC ... still the power surge would be important
    Oh, but I meant the CSAC should be *in addition* to TC. The TC scheme would handle the "normal" TCXO corrections, and then the CSAC would correct only what TC cannot---crystal oscillator aging. The timescale over which it would be useful to have CSAC disciplining would depend on aging rate and predictability---anywhere from a few days to a few months seems plausible.

    You're right, of course, that if you can afford to run the CSAC often enough to do TC as well, then that's fine, no problem.

    Incidentally, these "atomic" watches that set themselves with LF radio (WWVB and friends) should really be internally building accurate models of their clocks so that if they ever should go autonomous they'd be getting the best performance possible. They'd need TC for this.

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