[Asterisk-Users] Woodpeckers

[Chris Albertson]

--- Steve Underwood <steveu at coppice.org> wrote:

> >
> A power spectrum plot will tell him he has a 60Hz hum. I think he 
> already knows that. I think he can definitely consider solutions
> without 
> following your suggestion. :-)

No,  It's not a "60Hz hum".  Yes, 60Hz is getting into the line
but the existing filters are removing the 60hz.  What he hears
is most likely 120Hz, 240Hz or something else or most likely
a combination of various multiples for 60hz.  

I'd bet that the tiny speaker inside a telephone handset can not
even reproduce a 60Hz tome.  Yes you can hear a hum but it's
the overtomes of 60 that you hear.  Many people can not even hear
down to 60Hz, some can but not everyone.  

If you were to design a filter wouldn't it be nice to know some
thing about the noise?  Is there a big peak at 360?  how broad is
that paek 5hz or 20hz?  I would expect the power spectrum of a
"hum" to have multiple peaks.



=====
Chris Albertson
  Home:   310-376-1029  chrisalbertson90278 at yahoo.com
  Cell:   310-990-7550
  Office: 310-336-5189  Christopher.J.Albertson at aero.org
  KG6OMK

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