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[DPRG] Sonar presentation: Thanks, Mistakes, Update

Subject: [DPRG] Sonar presentation: Thanks, Mistakes, Update
From: Jeff Koenig jkoenig at airmail.net
Date: Tue Feb 22 18:33:40 CST 2005

John Swindle wrote:
> Thanks for all your questions and feedback during my sonar presentation.

Thanks for _presenting_ it!  It was one of the most interesting
presentations that  I've seen.

> 1. I said that a linear system did not tolerate infinite accelerations. I
> must have made that up. (...) linear systems don't care...

Yes, but any practical linear system will have a frequency limit (Does a
Bode plot show this?) , and a step function's Fourier transform implies an
infinite frequency.  So, is it proper to say that a _practical_ linear
system will show distortion when hit with a step function?

> ...I'd already made a different waveform without infinite acceleration,
but it wasn't a haversine.

Does this shape have a name?  I'm seriously considering dusting off my
Signals and Systems book...I seem to have forgotten most of what little I
ever understood about the subject.

> 3. I said that light didn't travel in a medium. Where were your rotten
> tomatoes?

Oh, I think most of us took this to mean "Light doesn't *require* a medium".

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

I'd be all for this follow-up lecture!  Fascinating subject.


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