Amateur Extra: Non-linear Phase Response

Which of these modes is most affected by non-linear phase response in a receiver IF filter?


A. Meteor Scatter

B. Single-Sideband voice

C. Digital

D. Video

The answer is C. Digital.  Why? Well, for one, the question is pretty vague.  If you’re using a Frequency Shift Keying (FSK) digital signal you probably won’t have any problems.  SSTV (D. Video) is a FSK mode.  B. Single-Sideband Voice doesn’t particularly care about phase at all.  And A. Meteor Scatter technically isn’t a “mode” at all, but rather a method of propagating the radio waves themselves.

However, if you are trying to transmit or decode a Phase Shift Keying (PSK) signal, then it only stands to reason that anything which alters that phase response in a way that is unexpected (like non-linear) will change encoding of the signal.  The end result will probably be unreadable.

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