Hi, A graphic tablet (11" square is a common size) should give you about 120 positions/mm for something like a hundred bucks. That's not very different from the "mouse" solution, but give you absolute position rather than relative. Regards, Jean-Louis Oneto
----- Original Message ----- From: "Rick Harold" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Monday, November 24, 2008 2:34 AM Subject: [time-nuts] position determination over short distance > All, > > I'm planning doing some experiments in distance measurement. They don't > deal with atomic time directly but with extreme short periods of time. > > I need to determine the position of a instrument with a 1mm accuracy or > less. > The instrument is not connected to a mechanical device but is separate & > independent. > The surface which the instrument is positioned on is close to the size of > a > 11"x11" square. > > I thought of using 1 RF transmitters (not sure of freq) on bottom of the > device near the surface. > The surface would have RF receivers on 3 or 4 edges/corners to receive the > signal. > > If each of the receivers positions are known and they then send a signal > to > a central circuit (again known positions) how can I differentiate the time > of arrival > at the central location? Does anybody know of a circuit/chip or system > which would determine the time 'difference'. > Obviously this is used to triangulate the position of the instrument. > Light travels 1 mm in ~3.3 picoseconds so I would suspect the > differentiator > would have to have that or better resolution. > It could also use some proportional method to extrapolate the position > since > the surface has a fixed size. > > Any ideas/thoughts? > > Thanks in advance. > > Rick Harold > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
