[BC] Re: Re Oscopes Bessel Null and FM

[WFIFeng@aol.com]

In a message dated 07/22/2006 11:06:59 AM Eastern Daylight Time, 
Xmitters at aol.com writes:

>  how would the overmod flasher behave under conditions of an 
>  idealized RF bandwidth then put in an RF bandwidth limiting filter that 
> emulates 
>  the Carson's rule formula. How would the overmod flasher behave with the 
> Carson 
>  filter installed?

If the filter were a "brick wall", wouldn't that start "punching holes" into 
the carrier as it's frequency swept past the filter's edge? I've seen this 
effect on audio files in Cool Edit, so it would most likely apply to RF as well.
Of course in the real world, brickwall filters don't exist, so it would 
introduce synchronous AM noise to the signal whenever it reached peak deviation. 
Methinks that would be far worse than a few percent overdeviation.

Thinking of which... it makes very little sense to me to run more than "100%" 
due to the bandwidth limitations of the receivers. Once you modulate that 
carrier outside the receiver's IF passband, it gets sharply attenuated, thus 
introducing some nasty distortion on peaks. 100% isn't just a good idea, and it 
isn't just the Law... it's those pesky Laws of Physics again. 

Today's audio processors can make it loud while keeping it legal, but there 
has to be a diminishing return in there, somewhere.

Willie...