From: Michael M. Butler (butler@comp-lib.org)
Date: Mon Dec 20 1999 - 20:56:54 MST
> In an automobile, even with the
>receiver and antenna sitting on the dashboard, it is unusable.
"My mileage varies." I have screwed-in a dash mount and gotten readings all
over the place without an external antenna.
<lots of good stuff elided>
>Some receivers are designed to receive signals from up to 12
>satellites at once,
That's the kind I'm using.
>GPS alone seems not very suitable for tracking people who do not wish to
>be tracked, partly because GPS works well only under open sky with no
>obstruction other than a thin layer of plastic surrounding the antenna,
>and partly because GPS alone only provides location data to the receiver,
>but not to a third party remote from the receiver. It would seem that
>transponders with embedded ID codes would be more effective. The
>transponders could be excited from cell phone base station transmitters,
>with the base station receivers being used to receive the signals from
>the transponders. Since cell phone base stations have multiple element
>antenna arrays in a horizontal plane, they can be used as precise
>azimuthal direction finders, with suitable software and calibration. If
>the signal from the transponder can be received by three base stations,
>the position of the transponder can be determined within a few feet, in
>principle.
What we have here is another need for something ("need" being task
specific, and ignoring the cultural issues for the moment) resembling what
the military have sometimes called "sensor fusion". I am not sure if they
get the term from the AI/robotics guys.
The Aetherwire folks are working on ultrawideband pulse gizmos to do local
positioning to centimeter accuracy at kilometer range, but not using cells.
One could easily imagine a cell-to-aetherwire relay/reporter/gateway with
differential GPS self location that might not require any cooperation from
the cell provider.
MMB
PS: if you can patent gizmos that run off muscles even though the
technology/power budget isn't viable today, that's one more sign of how
broken even the physical-artifact patent system is...
>Ron Kean
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