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    Re: Position from a Clock with Photo Diode
    From: Brooke Clarke
    Date: 2005 Jun 6, 20:20 -0700

    Hi Frank:
    Thanks for that link.  They archive the sunrise and sunset times along
    with other more frequent data and then send the data to a satellite.
    Very cleaver and much easier than I was thinking of.
    Have Fun,
    Brooke Clarke, N6GCE
    w/Java http://www.PRC68.com
    w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml
    Frank Reed wrote:
    > Brooke C you wrote:
    > "Suppose that a clock  that keeps UTC time to within 1 second has a photo
    > sensor with an analog  output to a computer.  The clock is indoors but
    > the room has a window to  the outside so although the clock is in the
    > shadow of the Sun it does see a  daily brightness curve.
    > How accurately can the clock determine where it is in  the world?"
    > This exists.
    > In fish tags!! I've posted on this before.  Here's something I wrote
    > previously:
    >>>This technique of navigation is  actively employed on a small device that
    > operates in an area inaccessible to GPS  signals --underwater. Do you have
    > $4200 to spare? Then you, too, can be the  proud honor of a celestial navigating
    > fish tag. I brought this up briefly on the  list over a year ago. Here's a link
    > to their web site and a description of the  device:
    > http://microwavetelemetry.com/Fish_PTTs/archival.php
    > They get  one-degree-ish estimated accuracy in latitude and longitude by
    > timing sunrise  and sunset (based on light levels corrected for depth, which is
    > measured by  pressure). <<
    > -FER
    > 42.0N 87.7W, or 41.4N  72.1W.
    > www.HistoricalAtlas.com/lunars

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