I have found that if I shift the passband I can still understand SSB
even though the DSP filter says it is only 1.1 khz wide. Try it and the
signal will be very clear once you hit the sweet spot. I think this is
because the intelligence carrying portion of the voice is not
necessarily in the center of the passband.
Buck
k4ia
On 3/31/2014 10:52 AM, George Danner wrote:
One of the things that Bell Labs found in adding loading coils to phone
lines (to reduce the high frequencies) was that in an audio system if you
reduce the high frequencies then you needed to also reduce the low
frequencies to keep the intelligibility constant. Since a phone system
needed intelligibility above fidelity; Bell Labs just decreased the coupling
capacitors to reduce the low end while using the line loading coils to
reduce the high frequencies.
I tend to use lo-cut to improve "listen ability" when I cut the high end.
I use a 1.8 kHz filter for a morning SSB net that has other nets 3 kHz away
usually on both sides. Some of the transmitters on the adjacent frequencies
can't fit in 5 kHz much less being 3 kHz away. The 1.8 kHz filter is the
best solution - the filter skirts along with the DSP skirts help the most I
can expect.
I would recommend adjusting Hi-Cut for the interference and Lo-Cut for the
best compromise on fidelity & intelligibility; if that switches in a tighter
filter, then that might be needed.
My 2 cents!
73
George AI4VZ
-----Original Message-----
From: Al
For years I have heard folks state that 1.8 kHz is mandatory for SSB
contesting... but I have never understood how one could put up with this
narrow bandwidth for long. I need more information hitting my ears and am
perfectly happy with letting the famous 'ear-brain' filter extract the
maximum from that information.
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