Mike Keitz wrote:

>Regardless of all this bickering about amplifiers, examine the big
>picture to see if the application's (sonar ranger attached to robot)
>performance will indeed be limited by amplifier noise.

>Acoustic and electrical interference from the machine and environment
>will likely be predominant sources of noise, even using a preamp of only
>moderate performance.

<SNIP>

Hear! Hear!  (...or is it, Here! Here! I can never remember...)

Mike has hit the nail on the head!  Following this thread has reminded me
of the old saying:

        "A camel is a racehorse designed by a committee."

My admittedly limited experience with the subject, as I stated in a
previous post, was that the Murata transducers worked fine in detecting a
binder to about 20 feet by hitting the Tx with some half-cycle pulses and
detecting them with a simple AGC circuit.  Of course, your mileage may
vary...  d;^)

Michael