[BC] Re: Re Oscopes Bessel Null and FM

[Xmitters@aol.com]

In a message dated 7/22/06 12:00:31 AM Central Daylight Time, 
broadcast-request at radiolists.net writes:

<< >This is an interesting question.  If the audio were "aggressively
 >processed", it would likely be clipped, thus having lots of odd-order
 >harmonics.  But wouldn't the Carson filter remove the sidebands that
 >represent the higher (harmonic) modulating frequencies -- which extend
 >farther from the carrier --  to a larger extent than the the sidebands
 >generated by lower (fundamental) fundamental frequencies?   If so, it
 >might act as a low-pass filter on the demodulated audio.
 
 Speaking for my company, our audio processors strictly limit their output 
 bandwidth regardless of how aggressive the processing is. Realistically, to 
 get "square waves" on FM, you would have to have one of the old analog 
 composite clippers on the air. The most popular of these did not band-limit 
 its output.
 
 Orban did not implement composite limiting until we had engineered a 
 solution that fully protected the pilot tone and subcarrier regions of 
 baseband regardless of the amount of limiting being used.
 
 Bob Orban 
  >>

My original question was framed under the assumption that the transmitter in 
question was fed with a properly set up baseband. Opening up the scenarion to 
include improper processing and other problems would have distracted from the 
original question. So the original question is, if the overmod flasher was 
winking at a rate of say, once per second and set to flash for anything over 100% 
modulation, 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?

Jeff Glass, BSEE CSRE
Chief Engineer
WNIU WNIJ
DeKalb, Illinois