| First, my apologies to Curtis Roads who's explanation of modulation index
and bandwidth is crystal clear, though apparently not idiot proof.
i wrote...
>>>>>>>>>>>>>>>
index of modulation I is defined as
I=D/M
where D is the amount of frequency deviation (in Hz).
if D is 100 Hz and Modulator M is 100 Hz, then the index of modulation is 1.0.
...
"because the bandwidth increases as the index of modulation increases, FM
can simulate an important property of instrumental tones. Namely, as the
amplitude increases, so does the bandwidth."
>>>>>>>>>>>>>>>>
he does go on to say:
"This is typical of many instruments... and is realized in FM by using
similar envelope shapes for both the carrier amplitude and index of
modulation."
the only suggestion i could make would be for this to be stated a couple of
lines sooner on the previous page.
i'm sure this is not the last time i will embarrass myself on this list.
and towards that end, i have posted two more questions under separate cover.
hope i didn't unduly confuse anyone who already understood this topic.
tolve
>>had to read your answers a couple of times, but seems that all of them, and
>>the book are correct, although they sound different. interesting.
>>
>>thanks guys!
>>tolve
>>
>>
>>
>Maybe I'm wrong, but........
>After thinking a little about it it seems to me that the amount of frequency
>deviation (D)
>is the same as the amplitude of the modulator.
>So I think the book is rigth, if one asumes that the amplitude of the
>modulator follows the
>amplitude of the instrument.
>
>----------------------------------------------------------------------------
>Roger Klaveness
>roger@apas.no
>----------------------------------------------------------------------------,
|