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    Re: Do We Still Need to Use Sextants?
    From: Brad Morris
    Date: 2013 Mar 28, 10:59 -0400

    I fear that the high frequency accelerations associated with a hand held device such as proposed will preclude an accurate vertical.  One only has to download one of the free apps *(such as Accelogger on the Android system) to observe the noise present.  This noise is the same issue that precludes inertial navigation using your cell phone, many have tried, all have failed.  Simply search for "inertial navigation" for your cell phone.  I know I want that application.

    Sure, the phone understands which way is generally down, so as to orient the screen, but that is far from understanding fine resolution vertical.

    So holding the device will most likely not work with chips present in modern smart or cell phones.

    Mounting the device to the vessel, however, will couple the large inertial mass of the vessel to the accelerometers, thus damping the high frequency noise and make the vertical much more attainable.

    How to then couple this vertical to the angle to the celestial object becomes more critical. 

    On Mar 28, 2013 10:26 AM, "David Fleming" <d.l.fleming.1---.com> wrote:

    A gravity based horizon is problematical, see bubble sextants. Hence many sights.
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