Hum ........ sounds like we need a updated / new version of the SM-220 here
?
Maybe, I'll change my mind after the demonstration ? Had a VOMAX and sold
that years ago , big mistake !
Do you use an external DSP with your ORION II because the internal DSP is no
good ?
Is the new RF speech processor really a money maker and used with older rigs
that have NO internal SP ?
Does excessive SP do any good at the other end of the QSO or is it just
NOISE !!
What we really need is something like the SM-220 to LOOK at the outgoing RF
and really see if it is something to be proud of and write home about !
Walt K8CV Royal Oak, MI.
----- Original Message -----
From: "Ken Brown" <ken.d.brown@hawaiiantel.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Tuesday, February 03, 2009 1:08 AM
Subject: [TenTec] RF speech processors
Hi all,
I think I know what an RF speech processor is. First I'll describe
what I think it is:
You connect your microphone audio to a little AM or DSB generator,
working at some frequency such as 455 kHz. Then you compress or even
clip that signal to increase the average power output. Probably goes
though some bandwidth limiting filters. After that it gets demodulated
back to audio, and feeds the microphone input of the SSB rig. Since the
compression/clipping/whatever is done at some "intermediate frequency"
and then demodulated back down to audio, the IMD "splatter" and
harmonics that are generated, don't get transmitted. Only bandwidth
limited audio goes to the microphone input of the SSB transmitter, and
the SSB transmitter audio stages and RF stages are never driven into
non-linearity. The transmitted signal bandwidth is limited by the usual
crystal or mechanical filters. You get a really dense high average power
signal.
I'm sure I may be wrong in some of the details, yet I'm pretty sure
I've got the basic principle right.
What I don't get is, with DSP used in the transmit section of a
modern rig, can't you write an algorithm running in the DSP system to do
that, and do it better, without resorting to this old technology? I'm
not saying it's bad. When a tried and true method works, it works. Just
seems like this is one of those functions that DSP ought to be able to do.
DE N6KB
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