[Elecraft] Question - for Educational Purposes

[Brett Howard]

Most people deal with WAY more than that on their cell phones every day.

On Fri, 2008-07-25 at 14:36 -0700, Alan Bloom wrote:
> On Fri, 2008-07-25 at 00:09, David Woolley (E.L) wrote:
> 
> > FIR filters cannot ring in the full sense of the word.  What they can do 
> > is to generate a finite pulse of a particular frequency, but that pulse 
> > is never longer than the filter length.  Long filter lengths result in a 
> > delay in the signal, which can become unacceptable in itself, so systems 
> > are not designed with extremely long filters.
> 
> For signals received by the human ear, the filter length would have to
> be really long to be objectionable.  For a symmetrical impulse response,
> the delay is 1/2 the filter length.  For example, assuming a 10 kHz
> sample rate and a 1000-tap filter, the delay is only 1/20 second. 
> 
> To get a decent shape factor, the filter length in seconds needs to be
> at least a few times 1/bandwidth.  Say 10/BW or so, resulting in 5/BW
> delay.  So even with a 50 Hz bandwidth, the delay only needs to be on
> the order of 1/10 second.  I don't think you'd ever notice that in
> normal on-the-air operation.
> 
> Al N1AL
> 
> 
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