But I can't even hear the 20KHz anymore let alone the harmonics. :-)
Chuck Norcutt
C.H.Ling wrote:
> To make it simple, all waveform other than sine wave is made up of the
> fundamental frequency + harmonics, for example a 20KHz square wave will
> contain 20KHz sine wave + 40KHz+60KHz+80KHz+100KHz...... sine wave in
> different ampitudes, so you need an amplifier of much higher bandwidth to
> pass a 20KHz square wave without smoothing out the corners.
>
> All amplifier quoted the bandwidth in sine wave and you also need to note
> the power they can handle in such a high frequency, that is called "power
> bandwidth", some just quote their bandwidth at 1W power output.
>
> C.H.Ling
>
> ----- Original Message -----
> From: "Chuck Norcutt"
>
>> If I had known the answer involved Fourier transforms (and I guess I
>> should have) I wouldn't have asked the question. :-)
>>
>> Chuck Norcutt
>>
>> ws wrote:
>>> The square root of the inverse Hilbert transform convoluted with the
>>> hypotenuse of the frequency, integrated over +-infinity time and you can
>>> show Why this is correct. :-)
>>>
>>> Actually the Fourier transform of a square wave shows odd harmonics that
>>> decrease in frequency, so a reasonable approximation requires summing
>>> a certain number of these harmonics, to recreate a square wave, But
>>> probably
>>> more import is the phase shift introduce with lower bandwidth systems.
>>>
>>> http://homepages.inf.ed.ac.uk/rbf/CVonline/LOCAL_COPIES/OWENS/LECT4/node2.html
>>>
>>> I do not know of any experimental listening tests of this, and I don't
>>> think I can
>>> hear past 12Khz these days. At one time, I could hear 16KHz sine wave
>>> but my wife doesn't think I can hear at all. Maybe she just needs more
>>> bandwidth? Unfortunately bandwidth usually means a lot of work.
>>>
>>> I just wish someone would inform the mobile phone developers that
>>> too much compression turns voices into noise.
>>>
>>> Wayne - say what?
>>>
>>> At 06:20 PM 1/24/2009, you wrote:
>>>> Why?
>>>>
>>>> Chuck Norcutt
>>>>
>>>> Ken Norton wrote:
>>>>
>>>>> It takes 160kHz of bandwidth to pass a a 20kHz square wave. Only 20kHz
>>>>> to
>>>>> pass a 20kHz sine wave.
>
--
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