Tim

I have done this before

Your design will depend on a few things.
How many of these will you produce ?
Larger quantities would suggest putting more of the=20
functionality in software to reduce cost.  If it is a
one-off design, are you doing this to get it done or to
make it a learning experience ?
How much flexibility do you want in the range finder ?
What does "a fair degree of accuracy" mean to you ? =20
   plus or minus 1 inch.... plus 10 percent of the measured distance ?

Keep in mind that increased accuracy requires that you compensate for
altitude, temperature, humidity and other variables.  One way to do this =
is to
have some fixed targets that you calibrate against. =20

How often do you want to measure the distance ?  How big is the target ?
Is the target hard, flat, soft, round, small, moving, etc.  ?

Feel free to contact me at wft@frii.com


Gus S. Calabrese
www.omegadogs.com
www.WFTelectronics.com
voice (303) 964 9670
fax (303) 285-3482 x5333

Are you a libertarian?  go to  http://www.lp.org/quiz/  to find out

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.