<Your recommendations are fine for YOUR ESSB ragchewing operation at
<higher power than US stations are permitted, but it's lousy advice for
<speech intelligibility under weak signal conditions, for the reasons
<noted. My advice is for the latter.
<IMO, if you need a parametric as opposed to octave-band EQ, there's
<something seriously wrong in your system. Maybe a poor choice of
<microphone, or a noisy shack.
<73, Jim K9YC
## Hundreds of tests have been run, with ssb signals right at the
noise level,
or slightly above the noise level. And in every case, increasing the
top end
improves speech intelligibility by a HUGE amount.
## all as we have done..is re-invented the wheel. This is all old
news.
Get yourself a copy of... Single Sideband Systems and Circuits, 2nd
edition.
Its also in any university library. 652 pages + a disc.
Its the definitive gold standard text for commercial SSB.
Go to chapter TWO,.... System Design Considerations. Read pages 12-22.
They depict no less than seven graphs, for articulation index,
intelligibility etc.
## In each graph, bottom end is cut off at 200 hz. Top end is
incremented,
starting at 2000 hz, then 2500 hz, then 3000 hz, then 4000 hz, 5000 hz,
6000 hz.
## Run the tests yourself if you dont believe me..or the rockwell
collins engineers
who wrote the book.
## NU9N has loads of various MP3 recordings, done by dozens of hams,
with
different TX BW segments. IE: <3 khz. 3000-3900 hz. 4000-4900 hz.
5000-6000 hz.
http://www.nu9n.com/mp3.html
## My deq2496 digital eq has a unique graphic eq.... its Q / BW can
be adjusted wider
than normal. The parametric eq is for fine tuning in a couple of
places. I have a
2nd and 3rd digital parametric eq, which will go from +12db.... down
to -48db. I use
that one to limit top end tx BW. I can stagger, or overlap the
bands...to slice off
the top end. Its the only way I can limit top end TX BW
externally, since the filters
in the xcvr are both 6 khz.
## shack is sound proof. Microphone is a RE-27.
Jim VE7RF
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