I agree that the semi-traditional RF Gain vs S-meter action has a
value -- showing the AGC threshold and S-level above threshold. There
is a place for this. There is also a place for a "true" signal
strength indicator. You might think that in these digital days, we
could have both -- or choose the one we want.
This is an area where DSP rigs like Orion have a lot of room for
improvement. They could give us a lot more information *about* our
signals - not just S reading, but noise & QRN properties, AGC action,
really good spectral displays that let you analyze modulation, etc.
On xmit, they could give you a scope display of modulation, IMD
analysis, etc. The rigs could support all kinds of digital modulation
and demodulation without soundcard kluges. Icom & Yaesu are edging in
this direction.
Progress is probably limited by the manufacturers' software budget -
and limited user demand (at the beginning). That's a good reason to
open the software process to volunteer developer/enthusiasts ala Flex
Radio. (The ultimate in soundcard kluges!) Easier said than done for
a mainline hardware company that uses proprietary development tools.
73 Martin AA6E
On 12/23/05, Grant Youngman <nq5t@comcast.net> wrote:
> >
> > With today's technology, it's not necessary to use this
> > indirect method.
> > Let's bury this dinosaur once and for all.
>
> Not so fast.
>
> The point of the S-Meter movement upward, as I recall the endless
> discussions of all of this regarding the Orion, is to give you a notion of
> the MINIMUM signal that will impact AGC, via the THRESHOLD setting. If you
> leave the S-meter reading unaffected, what does it tell you ... Not much.
>
> This "artifact of a bygone era" is telling you what signal level is required
> to affect AGC. For example, if you have an s-7 average noise level, one
> might, to keep things a bit quieter, increase THRESHOLD until the meter read
> about s-7. At least that was the point as I recall it, and I've always found
> it useful for that purpose. And why not? You are unlikely to hear any rare
> DX below this level, anyway. And it sure keeps the nosie level down,
> without any reduction in RF (IF) gain.
>
> The coupling of RF GAIN and THRESHOLD in one control in later Orion firmware
> releases was done to satisfy a lot of people who couldn't get their brain
> straight about THRESHOLD (the level at which AGC action would begin, RF GAIN
> (really an IF gain control), and the fact that there were two separate
> controls with quite different functions.
>
> So T-T simplified things a bit by providing some THRESHOLD shift as RF gain
> is adjusted. But you can still set threshold as you like, since the control
> is still there. Perhaps, once again, some refresher on why this is set up
> to do what it does would be in order :-)
>
> Grant/NQ5T
>
>
>
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--
martin.ewing@gmail.com
http://blog.aa6e.net
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