[Test-Equipment] FS: Heath IM4180 FM deviation meter

[WA5CAB at cs.com]

Actually, that is not the case.  The actual carrier does change frequency.  
F3 (FM voice) is perhaps harder to wrap your mind around but F1 (FSK) is easy 
to understand.  The carrier alternates between two discrete frequencies 
commonly called Mark and Space.  With an up and running FSK station it is easy to 
demonstrate this.  In this case, the deviation (or peak deaviation, which is the 
same) is equal to the shift.  The bandwith is greater than the deviation.



In a message dated 4/21/2008 8:15:57 PM Central Daylight Time, 
dufferjames at hotmail.com writes: 
> While the provided answer to your question will suffice, actually Frequency 
> Modulation (FM), the carrier does not change in frequency, the amplitude 
> varies, this can be observed with a spectrum analyzer and proven 
> mathmematically.  The modulated wave has various side frequencies that vary in both 
> frequency and amplitude depending on the modulating source.  AM (Amplitude 
> Modulation) the carrier is constant but the modulated composite varies in amplitude as 
> a result of the combination of the carrier and side frequencies.
> 

Robert Downs - Houston
<http://www.wa5cab.com> (Web Store)
MVPA 9480
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