[TenTec] RE: DIgital Signal Processing

[Martin Ewing]

I think there is a useful distinction between the various CPUs, and it's 
important for the Orion.

TT doesn't tell us quite enough about the logical architecture of the 
Orion, but here's what I've learned so far.  The "Sharc" DSP chips do 
the filtering, detection, and modulation.

But the "Dragonball" processor (Mot 68000 family) handles the LCD, VFO 
control, the keyer (with jitter), serial I/O, and front panel 
functions.  Most of the firmware problems seem to be in the Dragonball code.

The interesting feature (for me) is that, while the control processor 
directs the DSP operation, the received audio/IF data are mostly not 
available to the control processor.  (Excepting the spectrum display) 
This means, among other things, that the LCD can't show a tuning 
indicator (for FSK or PSK), can't show demodulated digital modes, etc.  
Also we can't show signal statistics that might help set up the digital 
AGC.  Some of these functions are available in the IC-7800, and 
hopefully we will see them "trickle down" to us proletarian Orion users. 
(no flames, please!)

I'd say that control processors, high-level signal processing (codecs), 
and the user interface is where the real innovation will be in the 
future, because RF and basic DSP are becoming commodities.   Anyone 
agree with that?

73, Martin


Merle Bone wrote:

>Mario,
>I really don't make much of a distinction between which of the CPUs are
>involved in performing the function digitally. While it is true that the
>general purpose processor has a different instruction set, it is still
>involved in digital control of the radio functions - part of digital signal
>processing. I recommend Doug Smith's book "Digital Signal Processing
>Technology." Doug was the main designer of the Orion. In his book he covers
>this by saying:
>
>"In general, modern DSP systems characterize and modify analog signals,
>producing other analog signals as their outputs. Note that this is not
>always the case, though; the output of a DSP circuit might just as well be
>the opening of a squelch gate or the triggering of a VOX."
>
>Merle - W0EWM
>
>
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