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[TenTec] Orions, IC-7800s...

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Subject: [TenTec] Orions, IC-7800s...
From: btippett@alum.mit.edu (Bill Tippett)
Date: Wed May 21 18:33:20 2003
KC2G wrote:
 >On the Orion: do the two processors parallel or co-process, or do they 
have discrete functions?

         It's my understanding that they are parallel, but I
don't know more about how resources are allocated.  Much of
this 32-bit DSP processor fanfare is academic BS anyway.  The
"DSP system" is limited by the 24-bit resolution of the ADC
and DAC.  It makes no difference if the DSP itself processes
32 bits or 64 bits, since the "DSP system" dynamic range is
limited by the ADC/DAC, not the DSP processor itself.  The
IC-7800 brochure shows a nice display of their 500 Hz DSP
filter (page 5) with 160 dB of ultimate rejection.  Wow!(NOT)
Fact is, that doesn't really matter since the DSP input and output
is limited by 24-bit ADC/DAC's which have a theoretical maximum
range of ~144 dB and a "DSP system" dynamic range more like
~105 dB because of internal analog amplifiers, temperature
compensation and other factors.  Beware of all the technical BS
that is floating around.  When ARRL tests both these radios
we may know the truth, but probably not until then.  It's
my strong opinion Orion will win the 5 kHz-spaced signal
measurements (IMDDR3, IP3, BDR) by a wide margin.

         The unique beauty of Orion is its strong analog signal
path (ham band-limited with narrow roofing filters at 9 MHz)
and excellent phase noise.  Without these, it would be just
another DSP radio, most of which have the same 24-bit ADC/DAC
and 32-bit DSP processors (IC-PRO2, IC-7800, Jupiter, etc.)
Actually its sub-RX is one of those too (i.e. a Jupiter)!

                                         73,  Bill  W4ZV

P.S.  Thanks to all for the "DC Power Supply Backup" comments!
Excellent suggestions which I will study carefully.

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