This idea is similar to the tracker.
I'm not a physics major. If I were, then I might realize that this project wouldn't work -- but I'm not. Let's say you have an antenna 10m long tuned to some frequency, and oscilloscopes at each end of the antenna picking up the signal. Now, you've got a transmitter at the same frequency, and you move it along the antenna. You could then use the difference between the two signals at the two ends of the antenna to get the position of the transmitter along the antenna. If the transmitter were past the end of the antenna, you should still be able to use the subtle difference between the signal on the two ends of the antenna to tell how far 'up' the antenna the signal is coming from. So you take a little box that's transmitting electromagnetic waves on frequency f, and you stick it to something (we'll say a plane for now). Now, you take three antennas tuned to frequency f, of length l, and you stick them perpendicular to each other so they form a three-dimensional 'plus' sign. One antenna picks up how far the transmitter is along the x axis, another for y, another for z. The strength of the signal wouldn't give you a reliable indication of how far the transmitter is, because it could be behind 10m of concrete and it would be indistinguishable from being 10000m away, so distance can't be accurately measured. However, the position in 3d space relative to the receiver box could be calculated. Cover the receiver box in 500 LEDs, and there could be one point on the outside of the receiver glowing, representing where the transmitter is from you. That is to say, if the transmitter were stuck to the side of a plane, and you were standing in a field as the plane went overhead, the point would seem to start on one side of the (spherical) receiver, and slowly pass over the top to the other side.
It would appear to me that this would be very useful to track, well, anything. If you put transmitters in the 8 corners of a gymnasium, all different frequencies, you could make a special receiver that can give you a very accurate indication of where it is within the confines of the gymnasium. If the gymnasium were a factory, or power plant, or game field, the data could be very useful. Sort of a land-based, localized GPS.
Bud - 2007-01-01 11:02:41
I thought the project described in http://www.comsoc.org/pci/private/2000/oct/bulusu.html might be helpful in providing a criteria for a "localization" system such as the one you describe.
old man - 2007-01-28 16:33:14
We need to talk about the Science Fair project I saw years ago which used three sensors at 3 corners of a 1 meter cube frame. Anything inside that frame could be 'scanned' by use of a mouse-like device that you clicked on each important control point on the object to be scanned. Then the difference in the time to the three receivers was calculated, which gave the accurate spot within the cube where that particular point was located. Once all the control points were entered, a wire-frame version of the object was rendered in 3D space. Seems that you could use the same s/w to locate any transmitter in 3D space, as you pointed out, even if outside the reference frame of the receivers.