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[DPRG] Sonar presentation: Thanks, Mistakes, Update

Subject: [DPRG] Sonar presentation: Thanks, Mistakes, Update
From: swindle at compuserve.com swindle at compuserve.com
Date: Tue Feb 22 13:14:39 CST 2005

Folks,

Thanks for all your questions and feedback during my sonar presentation.
And thanks for listening. It was about sound, after all. Thanks to Ron for
offering his PC, to Scott for his PC also and for saving the day with the
A/V equipment and to Dale for surreptitiously putting me on the schedule.
Thanks to Will Kuhnle for books and ideas.

I made at least three mistakes in the presentation. Let me know if there
were more!

1. I said that a linear system did not tolerate infinite accelerations. I
must have made that up. I was trying to make waveforms that did not depend
on infinite accelerations, so as to reduce distortions, but linear systems
don't care. Hitting a system with an impulse twice as strong gives twice
the response unless there's nonlinear distortion.

2. I said that haversines didn't have infinite accelerations. I knew that
was wrong when I said it. (Did George?) I'd already made a different
waveform without infinite acceleration, but it wasn't a haversine.

3. I said that light didn't travel in a medium. Where were your rotten
tomatoes? I should have just said that the movement of a uniform medium
does affect sound whereas it does not affect light. Stars twinkle because
the moving air is not a uniform medium.

If y'all want it, I could do a follow-up presentation on the really
interesting stuff: smart blanking, overlapping echoes and spheroids.

Remember: Strength is irrelevant. Pressure is irrelevant.

Later,
John


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