I don't think we disagree, Tom. Are you saying
that the DSP in the FT1000MP and or TS950SDX is
at 38KHz? I thought they were at audio, but admittedly,
I never looked at the block diagrams. I just assumed
they were at audio since they both use first and
second IF crystal filters. As you say, even if they
aren't at audio, they might as well be. Myself I like
this combination, as it gives you DSP capabilities like
bandwidth flexibility, linear-phase filter response,
etc, along with the dynamic range robustness of analog.
Of course, one can get the same thing with an add-on
DSP filter, like the Timewave.
A friend of mine has a TS-870 which has wonderful
audio, auto-notch, and seemingly infinite resolution
on filter characteristics. Unfortunately, it is
useless in high dynamic range environments without
add-on crystal filters.
73 de Mike, W4EF..................
----------
From: Tom Rauch[SMTP:w8ji@contesting.com]
Reply To: W8JI@contesting.com
Sent: Thursday, March 16, 2000 7:19 AM
To: Michael Tope
Cc: amps@contesting.com
Subject: RE: [AMPS] Receiver performance
Date sent: Thu, 16 Mar 2000 04:21:54 -0800
From: Michael Tope <W4EF@pacbell.net>
Subject: RE: [AMPS] Receiver performance
To: "amps@contesting.com" <amps@contesting.com>,
"'G3SEK'" <g3sek@ifwtech.demon.co.uk>,
"'Peter Chadwick'" <Peter_Chadwick@mitel.com>
> e.g. proper gain distribution, then it will work. Unfortunately,
> with the current level of technology available, sound design
> principles seem to dictate that the DSP appear in the audio
> section. Hybrid rigs like the FT1000MP and TS950SDX appear to
> be the way to go.
38 kHz is a lot closer to audio than 9 MHz would be.
The flaw is in our "labels".
The shortfall of DSPs aren't "frequency" problems or "AGC"
problems.
Moving the DSP from 300-3000 Hz to 38.000- 41.300 kHz won't
cure the problems, and neither will moving it into the AGC loop.
The problem is dynamic range, and the fact the DSP is way down
the chain from the mixers. The DSP doesn't have the resolution,
speed, or power to process ahead of the narrow IF filters without
screwing up something else.
Once it is after the narrow filters, it might as well be at audio.
73, Tom W8JI
w8ji@contesting.com
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