"Blunkett u-turn on data privacy plans"

[Ian G Batten]

On Tue, 04 Mar 2003, Roland Perry wrote:

> In message <1165392191-7086274@espace.net>, Fearghas McKay
> <fm-lists@st-kilda.org> writes
> 
> >no not normal GPS receivers - two antenna and a specialised box that
> >compares the difference.

Sure.  But not to 100 micron resolution.  That's four orders of
magnitude smaller that the wavelength being used to measure it.

> However, my practical experience and what I've read says that yes, I
> would believe that a suitable receiver could easily detect relative
> yaw/pitch movements of a ship of the order of a few cm (and back) at
> relative speeds of a few cm per second. Especially if using doppler
> enhancement:
> 
> http://www.racelogic.co.uk/vbox/gps.htm

Or, in three dimensions,
http://airtraffic1.stanford.edu/~uav/body_index.html.  However, note
that (a) the required precision is three or more orders of magnitude
less than the original claim and (b) they have their hands held by
accelerometers, inertial navigation platforms, wheel-pulse equipment and
suchlike.

ian