On 2022-05-20 8:36 PM, jerry wrote:
> I remember reading a magazine article many years ago...
QST, Dec 1977, Nov and Dec 1978 also the ARRL Handbook, 57th
Edition (1980).
They showed a hole of frequencies in the normal human voice audio
spectrum where there is not much energy. It was proposed to create
a new modulation where the higher frequencies would be shifted down
into the hole - thus letting the SSB signal take up less spectrum -
and then shifting those audio frequencies back up at the receive
end.
I think it was called NBVM (narrow band voice modulation). Used
a hard lowpass filter around 600 Hz to preserve the low audio,
a bandpass filter to "select" 1500-2500 Hz, a balanced modullator
with a 3100 Hz "carrier" and pandpass filter to select the lower
sideband. This resulted in the 1500 - 2500 Hz audio being inverted
into 600 Hz - 1600 Hz and the total transmitted voice bandwith of
just 1400 Hz (200-1600 Hz).
73,
... Joe, W4TV
On 2022-05-20 8:36 PM, jerry wrote:
I remember reading a magazine article many years ago... They showed a
hole of frequencies in the normal human voice audio
spectrum where there is not much energy. It was proposed to create a
new modulation where the higher frequencies would be
shifted down into the hole - thus letting the SSB signal take up less
spectrum - and then shifting those audio frequencies
back up at the receive end.
Thinking about it...that's the sort of thing I would have expected to
read in Ham Radio magazine. I miss it.
- Jerry KF6VB
On 2022-05-20 17:10, Walter Underwood wrote:
About seven years ago, there was an extended discussion on this list
about equalization settings for transmit. I collected all the settings
people used and posted about the majority contour.
https://observer.wunderwood.org/2015/09/09/transmit-audio-and-compression-with-the-elecraft-kx3/
wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)
On May 20, 2022, at 6:07 PM, Bob McGraw <rmcg...@benlomand.net> wrote:
Oh yes it is there on many SSB signals where the OP is a male. That
is where most of the fundamental male voice energy occurs. Those
signals which look uniform across the SSB TX bandpass do sound good.
I attribute this to the fact most hams will "boost this and boost
that" and never give thoughts to attenuating. In fact the
characteristics of the EQ in the boost mode are noticeable different
than the attenuate mode. Yes, one can hear the difference.
In my world of pro audio, it is a practice to attenuate first and
then boost if absolutely necessary. Hams just can't get over the
fact they must always have more.......boost boost boost.
So if ones signal is muddy or bassy, what's to do? Attenuate the
low end first, and rarely if ever, boost the high end. Of course
boosting the high end will make it brighter, but not attenuating the
low end will consume lots of unnecessary transmitter power not being
used for effective communications. 50Hz - 16dB, 100Hz -16dB, 200Hz -
16dB, 400Hz - 9dB, 800Hz - 0dB, 1.6kHz - 0dB, 2.4kHz +0dB, 2.4kHz
+3dB, 3.2kHz + 6 dB.
Works for me.
73
Bob, K4TAX
On 5/20/2022 4:30 PM, elecraft-requ...@mailman.qth.net wrote:
Message: 8
Date: Thu, 19 May 2022 02:14:10 +0000 (UTC)
From: Al Lorona<alor...@sbcglobal.net>
To: Elecraft Reflector<elecraft@mailman.qth.net>
Subject: [Elecraft] [OT] The dreaded 400 Hz hump
Message-ID:<1840135010.161126.1652926450...@mail.yahoo.com>
Content-Type: text/plain; charset=UTF-8
Have you studied how SSB signals look on your panadapter? I believe
about 90% of all phone signals have a very pronounced peak at about
400 or 500 Hz. This peak is sometimes 10 dB (or more) higher than
the rest of the bandwidth. This is wasted power and, to my ear,
makes signals sound muddier.
On the other hand, every once in a while you'll see a signal that
has a more or less flat frequency response, without any huge peaks.
Sometimes, a signal will actually have slightly*more* power in the
higher frequencies, say, 2000 Hz and higher. I've noticed that these
signals have much more articulation and punch. But these signals are
all too scarce.
It's pretty well known that the aging population of hams
collectively suffers from a high frequency hearing loss. It seems to
me that this is even more reason to carefully shape your frequency
response and cut the dreaded 400 Hz hump.
R,
Al? W6LX/4
--
IF ONE EXPECTS COMPUTERS AND TECHNOLOGY TO SOLVE THEIR PROBLEMS,
ONE DOESN'T UNDERSTAND COMPUTERS AND TECHNOLOGY
AND ONE DOESN'T UNDERSTAND THEIR PROBLEMS."
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