In answer to your questions, I don't use external DSP since I don't think
there is not much more that can be done to receive audio to make it more
intelligible. None of the implementations of DSP I've tried have made an
uncopyable signal copyable, especially with SSB, although someday that may
change.
Old rigs without SP will certainly benefit from the new processor, or any
processor for that matter, but it remains to be seen what it will do with
new radios like the Orions, Omni VII's, K3's etc. The only radio I ever
owned with a true RF SP built in was my old Yaesu FT-301D and it was about
the only thing good on the radio! When I turned it on, I could see the
average plate current on the amp nearly double. But what will happen when
highly processed audio runs into the 'over-protective' ALC in the Orion is
the big question. The 'dueling ALC's' in the Orions, one hardware, the
other software, is why everyone has noticed that they just don't drive
amplifiers the way other rigs do. I did a careful comparison to my TS-870
and the 870 was the clear winner.
Speech clipping (as opposed to compression) does result in a more usable
signal and it also makes more noise, but in a pile-up, noise can obscure a
competitor and get you the QSO first. It sounds like "dirty pool", but it
works :-)
You're right...a good o-scope will show you the average power better than a
meter. I need to dust mine off and hook it up!
Ron N6IE
www.N6IE.com
----- Original Message -----
From: <waltk8cv4612amos@att.net>
To: <ken.d.brown@hawaiiantel.net>; "Discussion of Ten-Tec Equipment"
<tentec@contesting.com>
Sent: Tuesday, February 03, 2009 3:39 AM
Subject: Re: [TenTec] RF speech processors
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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