--- Tommy <aldermant@alltel.net> wrote:
> I think most of us recognize W8JI for his practical
> and technical experience. In World Radio, here is
> what W8JI has to say:
>
> "Many of us think modern radios with advanced
> multiple DSP systems and LCD displays have moved far
> beyond vacuum tube performance, but in truth they
> haven't moved as far as we are being led to believe.
> Modern amateur receivers using DSP systems are very
> limited in dynamic range.. Despite marketing hype,
> they really have about the same dynamic performance
> as the poor 2nd mixer in the R4C. When all of the
> selectivity is in DSP, at the very best you can
> expect performance within the roofing filter
> bandwidth to be mediocre"
I have always found W8JI's comments and perspectives
to be well reasoned and sound. I will also agree with
most of what's been said in the article excerpt
referenced above. What I do find troubling though is
how often his remarks, such as those above, are turned
into a broadly held belief/position by the DSP
naysayers that "DSP and good dynamic range
performance" will always be mutually exclusive. Simply
not true, they only underscore the reality that DSP IF
systems can only be as good as the analog components
that precede them, that is where many DSP IF radios to
date have come up short. A good DSP IF radio design
simply does not allow the A to D and DSP stages to
ever see signals that are outside of those component's
own dynamic range. Is that concept really any
different than a radio designer choosing inappropriate
components for the analog front end design of a 100%
analog radio? From what I can see one of the
fundamental design points of the Orion is to feed the
DSP IF stage(s) properly, by most measures I believe
that they've succeeded.
As for the LCD displays and the like I have yet to see
one that truly impresses me. So in a round-about way I
basically agree with Tom's sentiment (as I perceive
it) there too. Where I think I depart from Tom's view
(and many others) is that that I beleive a radio's
display is something that should be made to be far
more useful and informative than any of them now are.
Especially so for finding out where the signals on a
band (or several bands) are; and how to get to any one
or all of those signals very quickly and efficiently
(hint: spinning a tuning knob is neither quick, or
efficient). Additionally based on his various comments
over the years I get the impression that for his style
of operating that kind of capability is not nearly as
important to him as it is for me, is that wrong? Of
course not. It's just a different set of operational
requirements (which loosely fall along the lines of
low/HF band DXing/contesting vs. V/UHF
DXing/contesting). So why can't our radios be designed
to accommodate both?
The main problem with the LCD displays on all of
today's radio's is that they are far too small to be
truly useful, and they are not very user definable, if
at all. Yes the new VGA outputs on the IC7800 and the
FTDX9000 do help for the display size issue, but it
really doesn't do much for their usability
limitations. Nor do they do much more than emulate the
basic radio displays from years ago, but why must they
be so limited?
Duane
N9DG
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