On Sat,9/6/2014 9:36 AM, Wayne Burdick wrote:
There seems to be some debate about how much FM deviation is required for PL tones used
to activate repeaters. There's a wide range of deviation values in use by transmitters,
and various "standard" recommendations. The question is how much is needed for
reliable operation in the real world.
I've always seen/heard 500 Hz deviation. The first link says 15%
deviation. The second quotes a standard that says 12%, and quotes email
from a reader saying that 12-14% provides the most reliable decoding
under marginal conditions. Several references note (correctly) that when
PL is heard it is nearly always the harmonics in a tone with distortion.
http://en.wikipedia.org/wiki/Continuous_Tone-Coded_Squelch_System
http://www.repeater-builder.com/tech-info/ctcss/ctcss-overview.html
http://www.radagast.org/~dplatt/hamradio/FARS_presentation_on_modulation.pdf
http://www.metrocor.net/info/ctcss.htm
73, Jim K9YC
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