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Old March 20th 04, 06:23 PM
Chief Suspect
 
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"Jay Heyl" wrote

http://www.wunclub.com/sounds/index.html


That's an interesting site. Does anyone know of a site that has
examples of signals at various SIO/SINPO ratings? I usually put down
some kind of rating in my logs, but I'm never sure if my idea of "barely
audible" is the same as anyone else's. It would be nice to have some
kind of example of various ratings from more experienced folks.

================================================
Here is some help from a perhaps dated guidebook issued by NASWA

Understanding Your S-Meter
DXing According to NASWA - 4th Ed. 1979
by Edward Shaw

Without a doubt the S-meter is perhaps one of the
most misunderstood pieces of equipment associated
with our hobby. The S-meter may be used by the
hobbyist to aid him/her in evaluating an incoming
signal.

To begin with, it may be best to explain briefly
that the S-meter is a simple voltage meter which
measures the output strength of the first IF
transformer in a receiver. The stronger the
signal, the higher the IF output voltage,
resulting in greater needle deflection on the
S-meter. The measurement shows strength in
decibels above a given standard. The word
decibel derives from Alexander Graham Bell,
thus a 'Bel' was a single measure, and deci-bel
meant 10 Bels.

Each S-unit is nominally double the value of the
preceding unit. That is to say, an S-6 reading is
twice as much signal as S-5, etc. The typical
S-meter is marked off in units from S-1 to S-9
with graduations after that for 10, 20, 30 or
more decibels above S-9. An S-meter gives only
relative strength of stations heard. A reading of
S-9 on one receiver may not be S-9 on another
receiver, even using the same antenna in the same
location. However, this is only because
manufacturers cannot or do not adhere to one
standard.

One prevalent standard among many professional
manufacturers of communications equipment (and
the U.S. military complex)is to adjust S-9 on the
meter for a 60 microvolt laboratory signal. This
would mean that an S-meter reading of S-8 would
be 30 microvolts; S-7 would be 15 microvolts, and
so on down to S-1 which would indicate something
less than 1/4 microvolt.

Depending on the sophistication of the receiver
at hand, and its ability to give an appreciable
signal-to-noise ratio, the S-meter needle
actually may never register below S-3 or so due
to the noise level itself keeping the needle
deflected up that far. Only under the most
controlled laboratory conditions can a
manufacturer's claims of .... i.e.
"1/4-microvolt" sensitivity be realized. In
reality a 1/4 microvolt signal amplified
sufficiently enough to be audible probably would
be so lost amid the amplified noise level as well,
that it would be undetectable.

In practical use of your S-meter to aid in
adjudging a fairly reasonble SINP evaluation, the
following guidelines are offered. They may or may
not be accepted by radio station engineers or
other DXers. Only the S factor is SINPO is
considered here, and one should not confuse it
with evaluations for QRM or QRN (respectively I
and N of the SINPO code). Graduations between S-1
and S-9 may vary in accuracy from meter to meter,
and from receiver to receiver.

S5 - The best possible local quality strength.
The carrier wave alone of such a signal will do
much to suppress QRM or QRN. The S-meter reading
is in excess of 20dB over S-9.

S4 - Strong signals between S6 and +20dB. Voice
and music are comfortably readable. Slight QRM
and/or QRN may be present. No trouble following
complete program with full understanding.

S3 - S-meter is S-4 to S-6 and music is readlily
identifiable. Voices are clear enough to follow
the gist of what is being said (or would be if
you understood the language).

S2 - S-meter registers between S-2 and S-4.
Familiar tunes are still recognized, but with
difficulty after some moments. Can still
differentiate between male or female announcers.
Can possibly still ID the language by tone,
inflection, gleaned words, etc.

S1 - S-meter is less than S-2. Cannot determine
whether male or female. Cannot recognize tunes or
language. Noise level is likely to be much louder
than the signal itself.

In the last case, an ethical listener cannot
claim certainty of identification, and the only
guide to suspects will be reports of others who
have heard a better signal from such a station.


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Old March 20th 04, 11:58 PM
Jay Heyl
 
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In article k6%6c.49140$KO3.160008@attbi_s02, "Chief Suspect" chief
says...

"Jay Heyl" wrote

http://www.wunclub.com/sounds/index.html

That's an interesting site. Does anyone know of a site that has
examples of signals at various SIO/SINPO ratings? I usually put down
some kind of rating in my logs, but I'm never sure if my idea of "barely
audible" is the same as anyone else's. It would be nice to have some
kind of example of various ratings from more experienced folks.

================================================
Here is some help from a perhaps dated guidebook issued by NASWA

Understanding Your S-Meter
DXing According to NASWA - 4th Ed. 1979
by Edward Shaw

Without a doubt the S-meter is perhaps one of the
most misunderstood pieces of equipment associated
with our hobby. The S-meter may be used by the
hobbyist to aid him/her in evaluating an incoming
signal.
... snip ...


Thanks, Chief. That does help.

-- Jay
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