[Premium-Rx] Group delay in the IF

[Gary Follett]

Actually, phase distortion is far more critical in FM than in any other 
mode. Phase distortion reflects directly as amplitude distortion. 
Please recall the phase modulation works equally well as frequency 
modulation in an FM set. Over the short term (say a few cycles), phase 
modulation cannot be differentiated from frequency modulation. As such, 
either a change in frequency or a short change in phase of the signal 
results in an amplitude change at the detector.  So any undesired phase 
errors reflect  directly in the audio output as amplitude distortion.

Gary