Does anybody know of a way to make a PIC measure time intervals shorter than
it's instruction cycle?  I need to measure the time between a transmitted
and a reflected radio pulse in the 3 ns range, and would like to do it with
a PIC.  Doing it directly is pretty much out of the question due to the slow
instruction cycles (200ns) , but maybe there's a trick that would make it
possible?  The overall code execution speed can take as long as needed, but
the nanosecond resolution must be reasonably accurate (+/- 1ns).

Ideas?  Has anybody faced a similar problem?  I'd love a point in the right
direction.  It seems this must have been solved for radar applications or
other wave-propagation measurements, but searching on Google doesn't turn up
much.

The application (so far) is just a thought experiment regarding
medium-distance ranging accurate to within a meter (about 1ns for
speed-of-light radio reflections), but it's something I'm pretty fascinated
with and if I can come up with a viable system I'd love to build it as an
educational project.

Thanks in advance!

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email listserv@mitvma.mit.edu with SET PICList DIGEST in the body