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Re: Ultrasonic

At 21:18 10/8/99 -0500, you wrote:
If the oscillator frequency is 40 kHz and you are pulsing at 120 Hz with
a 50% duty cycle, then the transducer is listening for 4.1 msec each
cycle. ....

Pete Lohstreter

I am not familiar with the model device Pete is refering to.
It sounds more like a doppler than a pulse sonar.

This is the way range finders and depth sounders work:
a steep narrow pulse shocks a piezo electric tranducer on its
natural frequency. This pulse is as narrow as possible while
retaining the desired sensitivity/range.

Just as a radar uses a pulse width in the range 0.1 to 1.0
microsecond, I would expect a short range pulse sonar to be
using a pulse width of 25 to 250 microseconds or so.

It would not be difficult to throw some light on the pulse
characteristic with a scope, I imagine.
brian whatcott <inet@intellisys.net>
Altus OK