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PL Deviation
How much PL deviation should I run? By Kevin Custer W3KKC |
In NBFM the standard is 15%. For a +/- 5 kHz system, this works out to 750 Hz.
I never liked running that much PL deviation because it usually isn't necessary. I have found that 500 to 650 cycles is fine and doesn't create any problems from running this lower level of deviation. If there is any trace of distortion in the PL signal, the PL level will sound louder than it really is. Be sure your modulator will handle the PL level you are trying to run. Phase Modulator Exciters in high-band or lower bands may have difficulty in reproducing the standard accepted amount of PL deviation. True FM modulators will work better and not introduce distortion on these low frequencies, and are preferred for repeater transmtters.
PL stands for "Private Line" and is a trademark name of Motorola Inc.
PL means the same thing as CTCSS, Call Guard, Channel Guard, Quiet Channel, etc.
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