[aprssig] "Best" packet decoder solution
Lynn W. Deffenbaugh (Mr)
ldeffenb at homeside.to
Mon Dec 27 10:44:12 CST 2010
Note that the one that is missing there is the KPC-3+ which, according
to what I've read, fails miserably if the signal is flat on the air (not
pre-emphasized) but de-emphasized on the receiving end before being fed
to the KPC-3. The KPC-3 apparently doesn't like the low tone being
louder than the high tone resulting in a lack of decoding.
Some have recommended that the audio interface for the KPC-3 be set up
so the transmit audio (KPC to radio) goes through the pre-emphasis
circuit, but the received audio (radio to KPC) be pulled directly from
the discriminator and before the de-emphasis (meaning, don't pull it
from the speaker output). This would mean that "correct" on-the-air
packets (pre-emphasized, with highs louder than lows) would be decoded
ok as would non-emphasized (both tones equal) packets.
I have a KPC-3+ here, but I haven't yet hooked it up to anything for
comparison to the TNCs listed in my previous e-mail. I haven't made
time for this because apparently the KPC-3+ also has trouble when
operated long term in KISS mode which is my preferred TNC interface.
Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32
Greg Clark wrote:
> Thanks, Lynn, exactly the info I was looking for!!!
> - Greg
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