On Tue, Nov 11, 1997 at 04:58:23PM -0800, Rick Dickinson wrote:

> By placing the transducers inside of pipes or cylinders lined with some
>  sound-absorbing substance (like velvet or some other cloth) we should be able

I've found the ultrasonic transducers are highly directional anyway. For
liquid-level measurements it's probably necessary to use a pipe, to avoid
reflections from the tank sides etc, but for free-air ranging it's not
particular necessary.

--
Clyde Smith-Stubbs               |            HI-TECH Software
Email: clyde@htsoft.com          |          Phone            Fax
WWW:   http://www.htsoft.com/    | USA: (408) 490 2885  (408) 490 2885
PGP:   finger clyde@htsoft.com   | AUS: +61 7 3354 2411 +61 7 3354 2422
---------------------------------------------------------------------------
ANSI C for the PIC! Now shipping! See www.htsoft.com for more info.