As I assume you know, FM stands for Frequency Modulation.  The standard for 
many years was a deviation of 5 KHz meaning when you modulate an FM carrier, 
it changes in frequency up to plus and minus 2.5 KHz.  Narrow FM modulation 
is a lesser deviation, 2.5 KHz and 2 KHz.  The reason for a narrow deviation 
is to allow a more efficient use of the radio spectrum.  We are talking 
about two way radio communications above and as a side note, Broadcast FM 
has a deviation of plus or minus 75 KHz. As the deviation widens, the 
fidelity of the transmitted audio increases.  This is why the deviation of 
FM broadcasts have such a wide deviation.

Howard #3

----- Original Message ----- 
From: "Richard B McDonald" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Saturday, April 25, 2015 10:26 AM
Subject: What is "FM Width"?


> Hi!
>
>
>
> So, I am aware that the "width" of an FM signal can be set to "wide" or
> "narrow", but what does that mean?  Under what circumstances would you use
> one or the other.
>
>
>
> 73,
>
> Richard KK6MRH 


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