[Test-Equipment] Q and filters

[Fuqua, Bill L]

  Some how folks confuse linear phase response, bandpass ripple and ringing.
Mathematically, you can't avoid ringing with narrow bandpass. You don't even have
to use resonance to determine this. Just understanding simple Fourier transform. 
  Fortunately both analysis agree. In fact one analysis leads to Heisenberg's uncertainty
principle. 
Delta F= bandwidth
Delta T= time resolution or ringing so to speak
 delta F x delta T > 1, then using Plank's constant E=hF and simple algebra you get
 delta E x Delta T>h published in Heisenberg's first paper on the subject.
This can be used to derive the relationship of position and momentum

73
Bill wa4lav
 
________________________________________
From: Test-Equipment [test-equipment-bounces at mailman.qth.net] on behalf of David [davidwhess at gmail.com]
Sent: Sunday, June 22, 2014 1:58 PM
To: Discussion of Electronic Test Equipment
Subject: Re: [Test-Equipment] Q and filters

>From what I remember, the tradeoff is high Q versus higher order.  For a given
bandwidth the two can be traded off and the later will yield a lower Q per
section and cleaner phase response.

On Sun, 22 Jun 2014 08:34:46 -0700, you wrote:

>Hello Carl,
>
>~ Ive built several of his passive filters to get rid of high frequency
>hiss, they work great compared to noisy and distorted active filters.
>
>What I can't quite believe is that it's possible to build a narrow passband
>filter (high Q?) without ringing. Am I missing something here?
>
>Cheers,
>
>Brian
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