I agree with George, and if I remember correctly the "old standard" used by
Collins was 100 uv.
Cheers!!
de Benton wb5twc
----- Original Message -----
From: "George, W5YR" <w5yr@att.net>
To: "Mark Erbaugh" <mark@microenh.com>
Cc: <tentec@contesting.com>
Sent: Thursday, August 22, 2002 9:42 AM
Subject: Re: [TenTec] Pegasus SMeter display
> In the real world, there isn't any . . . depends upon the make and model
of
> receiver and its design and the calibration and alignment of the
particular
> receiver.
>
> We tend to use the 6 dB/S-unit as a convenience but it has no regulatory
or
> technical standing. Same situation as the "S9 = 50 uv" "standard." Both
> have become urban myths based upon the calibration procedures that some
> companies have used in the past.
>
> With any given receiver, you will find variation of the S-9 calibration
> point from band to band and even within a band. You will also find
> variations in specific S-unit delta values over the signal range, and
again
> within a band and from band to band. Most amateur receivers will show more
> S-meter activity at the low end of the scale - fewer dB per S-unit mark -
> that at the mid and upper ranges.
>
> Only expensive commercial and military receivers actually determine and
> indicate the signal level at the antenna terminals and/or have scales
> calibrated in software to deal with in-band and band-to-band calibration
> variations.
>
> There is probably nothing wrong with using the informally defined "S Unit"
> of 6 dB as a convenient measure, but one should not expect any amateur
> receiver to possess that actual calibration within and over all bands.
>
> 73/72/oo, George W5YR - the Yellow Rose of Texas
> Fairview, TX 30 mi NE of Dallas in Collin county EM13qe
> Amateur Radio W5YR, in the 56th year and it just keeps getting better!
> QRP-L 1373 NETXQRP 6 SOC 262 COG 8 FPQRP 404 TEN-X 11771 I-LINK 11735
> Icom IC-756PRO #02121 Kachina 505 DSP #91900556 Icom IC-765 #02437
>
>
> Mark Erbaugh wrote:
> >
> > The Pegasus Programmer's Reference Guide (PRG) says that the signal
strength
> > query returns results that represent S-Units (and fractional S-Units).
This
> > makes it pretty easy to display signals up to S-9, but what about
signals
> > stronger than S-9? Most people expect a meter calibrated in db over S-9.
I
> > designed my display assuming 6 db / S. Thus S10 would be 6db over S9,
S11 12
> > db over S9. S13 18 db over S9, and so on. While I don't have radios
setup
> > for side by side comparisons, it seemed that the strong signals on 75
were
> > reading higher with this display scheme than I saw on other radios.
> >
> > Then today, I'm reading a 1296 MHz antenna review in the latest QST and
the
> > author says the signals went from S3 to S8, an increase of 15 db. That's
> > only 3 db per SUnit.
> >
> > So, just what is the relationship between db and SUnits?
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