On Tue, 2 Dec 1997 22:28:23 +1000 "Paul B. Webster VK2BZC" writes: >Frank A. Vorstenbosch 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. For long range, quiet environments, it may likely be more practical and less expensive to increase the transmitter power and/or acoustic "antenna" gain than to go to great lengths with exotic preamps. These approaches also counteract environmental noise, a more sensitive receiver doesn't.