Why not GPS atomic clock?

Thread: Why not GPS atomic clock?

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  1. #1
    Member avohass's Avatar
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    Why not GPS atomic clock?

    I am just wondering why Casio doesn't use the on-board GPS atomic clock for atomic time keeping?The GPS system consists of a constellation of 24 orbiting satellites. Each satellite has an on-board atomic clock, providing a highly accurate timing reference to within a few nanoseconds of UTC.

    The current earth positioned atomic clock is very limited in reception to certain perimeters only. The most being 3000km radius at Fort Collins, Colorado USA. It is also effected by weather , atmospheric condition, seasonal changes, mountain or other geological formations.

    I think the use of GPS atomic clock will be fair to all Casio users all over the world. Though the GPS signal can't travel through metal and brickwork but it can penetrates glass and plastic. The time will automatically be calibrated in the open or by putting the watch close to the window.
    Last edited by avohass; September 1st, 2009 at 16:29.

  2. #2
    Member Seamaster73's Avatar
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    Re: Why not GPS atomic clock?

    I've asked the question before. Too power hungry is the answer.

  3. #3
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    Re: Why not GPS atomic clock?

    no doubt it is more power hungry.

    take a look at the broadcomm bcm4750, touted for its small size, measuring a minimum of 3.6 x 3.6 mm - and that doesn't count the antenna. if we look at the suunto x10, you see three characteristics clear as day: high cost, low battery life, and large size.

    the complexity of the gps signal, a gigahertz transmission vs 60khz for wwbv, is orders of magnitude greater. that must be partly why you can be sure that casio would have to source this component, while i bet they make all or most all of their current multiband 6 receiver. and the time encoding mechanism on wwvb and others is so dead-simple, a school kid could encode / decode it with pencil and paper (see the colors in my sig?). paying for another oem chip will be expensive, but already we see unrest about premium prices for dlc and other exclusive technologies. do we want more expensive chips just to pursue an egalitarian world-wide sync-- in regions where casio probably already offers non atomic options or simply isn't concerned about? one could even say that if those citizens were so disenfranchised, their government could establish a time service and wait the few years for manufacturers to catch up, just like what happened in china. although ronald regan and the us have made gps accessible and accurate world wide for the common good, its longevity and service is not guaranteed and individual countries may want a time authority under their own auspice.

    another technical detail, and i don't know the full meaning of this, is that many fixed position gps time receivers also cross check the gps time with the wwvb long wave transmission, maybe because nist in colorado is still america's official 'source' for utc.

    and don't even get started reading about how the atomic clocks in gps satellites have to be corrected for relativistic time shifting (time slows with speed but accelerates with less gravity, thus the correction for an elliptically-orbiting satellite varies over time between earth utc time and the satellite's time).

    the actual nighttime propagation of wwvb can reach into south america, well over 5000 km. based on people reporting the latest watches syncing better, i think casio is on the right track: refining known technology that they can pack in to tiny, solar-charged formats for under $100.
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  5. #4
    Member Queen6's Avatar
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    Picture Re: Why not GPS atomic clock?

    Quote Originally Posted by avohass View Post
    I am just wondering why Casio doesn't use the on-board GPS atomic clock for atomic time keeping?The GPS system consists of a constellation of 24 orbiting satellites. Each satellite has an on-board atomic clock, providing a highly accurate timing reference to within a few nanoseconds of UTC.

    The current earth positioned atomic clock is very limited in reception to certain perimeters only. The most being 3000km radius at Fort Collins, Colorado USA. It is also effected by weather , atmospheric condition, seasonal changes, mountain or other geological formations.

    I think the use of GPS atomic clock will be fair to all Casio users all over the world. Though the GPS signal can't travel through metal and brickwork but it can penetrates glass and plastic. The time will automatically be calibrated in the open or by putting the watch close to the window.

    They do, search for a GPR-100

    the watch works exactly as advertised, however as others have pointed out battery run time is the weak point of all present day GPS enabled watches.

    Q-6

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