[TenTec] Noise Reduction Setting

Thu Dec 7 00:31:52 EST 2006

My two and a half cents worth....

I cannot comment on ALL the posts on this subject.  People have widely
divergent views on the effectiveness of the noise reduction software now (or
previously) present in the Orion.

But, I can say this, and have said similar before.

Whether CW or SSB, narrow bandwidths (up to a point) will often help by
excluding adjacent noise and thus making the available signal stand out more
clearly.  There is no debate about that much.  Obviously it can be over
done.  Your mileage will vary, so there is no one perfect bandwidth to use
for any given signal.

But, look beyond that.  Once the bandwidth has reached its optimum (that is,
as narrow as seems appropriate to the circumstances) it is NOT true that a
properly functioning noise reducer can produce no more gains.  This is plain
wrong.

However narrow the bandwidth, there is still a mixture of noise and signal
left inside the pass band.  Furthermore, properly implemented algorithms can
identify much of this noise and eliminate it.  This is done by digitizing
the signal, then doing Digital Signal Processing (DSP) such as looking for
correlations for example (there are other methods)...then retaining that
portion of the digital content and actually deleting the noise portion.
Then we go from digital back to analog, and you have the de-noised signal.

This takes a lot of processing.  That is why only the military can afford to
do it directly on HF frequency signals.  So we do it at audio signals - like
the 14 khz stage of the Orion.  They call it IF DSP, because its before the
detector, but 14 kilohertz is an audio frequency no matter what we call it.

Bottom line - this should work very well.  If done well, it will outperform
bandwidth reduction alone.  Timewave does a great job of this in their add
on boxes.  I've used really expensive equipment at work to do it at much
higher frequencies.

So all that is left if to decide if it is done effectively in the Orion.

Opinions vary - very widely !

I'd tend to say that it works moderately well - but not by any means
perfectly.  Given the complexity of the radio and the posts we have all seen
where at least some people get confused by the radio, I'd say at least some
of the problems are people defeating themselves by not fully understanding
what they are trying to accomplish and how to accomplish it.  Most probably
don't have any idea of the math and processing involved.

On the other hand, some of the complaints are likely justified.

Is it, bottom line, better than the alternatives ?  I'd say yes because the
radio combines a really great RF and IF front end with a strong DSP
processor at the far end (audio end) of the chain.  This is more than most
radios offer.

Is it perfect ?  Nope.

Ok...end rant !  :)

73 de Gary, AA2IZ

----- Original Message ----- 
From: "Emil Borys" <w9nm at sbcglobal.net>
To: <tentec at contesting.com>
Sent: Thursday, December 07, 2006 12:14 AM
Subject: [TenTec] Noise Reduction Setting

> Grant,
>
> I searched the archive before I called TenTec and before I posted here.
After reading applicable archives there are almost as many opinions as
posts.  If any consensus can be gleaned from the posts, it is that the DSP
NR does not work as advertised.
>
> I really don't like to clamp down on bandwidth unless absolutely
necessary.
>
> Reasons for not liking 200 or 300 hz  bw:
>
> I like to ragchew and virtually every qso turns into a 3 or or 4 way
conversation.  When participants are not closely spotted, copying different
tone frequencies is no problem... when they fall off the edge it's down
right difficult for me.
>
> With  limited operating time available, my speed doesn't get much over 35
to 40 wpm (I am in awe of the 60 wpm crowd.)  Come the end of Mar I am
pretty much qrt until Nov.  I really haven't been able to become as
proficient at cw as I'd like.... that is probably why I find that it is
easier and more comfortable to copy said speeds at wider bandwidths and high
noise frequencies.
>
> For me, narrow bandwidth is no panacea for copying code.  While the
absolute noise is reduced  as bandwidth is reduced, the resultant frequency
content of remaining noise can be such that ease of copy is reduced, not
enhanced.
>
> I really like to use a wider bandwidth so that I can hear what's going on
close by, someone may be trying to break, again not closely spotted, close
signals appear via qsb, etc.
>
> In your statement that "If you operate CW with reasonably narrow
bandwidths, DSP NR is largely superfluous." I disagree with you, if you are
making that statement in a general context.  Maybe that statement may be
true if you are speaking of the apparent operation of Orions... as many here
have described here.  I have had an IC-7800 for approx a year and a half...
it excels at taking a cw signal that is r5, but in noise, greatly
diminishing the noise and thus removing the fatigue caused by continuous
noise during long term copy...  and also allowing a wider bandwidth.  Will
the DSP make an r0 sig into an r5... no.  But the 7800's DSP will make any
readability level easier and/or less fatiguing to copy, the very extremes
notwithstanding.
>
> Next topic:
>
> I am amazed at some of the condescending and borderline snotty tones in
some of the posts, whenever performance/operation of an Orion is questioned.
In addition, some appear that they do not read the question and
circumstances given in the original post... and render contextually
irrelevant comments... aimed at ????
>
> I'm a graduate EE, received my General when I was in 8th grade and a 1st
Class Commercial with radiotelegraph and marine radar endorsements a year
later, and my employers have a good handful of patents with my name on them.
Maybe because I've been in corporate management and not a practicing
engineer for the last 10 or 15 years, I am not as qualified as many of you
on this list... but to receive comments as 'Turn the RF Gain down'  after it
has been stated that RF Gain and all other adjustment had been tried, makes
me wonder why someone values their time so cheaply, to be spent by making
such an inane comment... and why they think that I value my time so cheaply
that I'd care to participate in their senseless blather.
>
>   And, "I've removed the button." is really a great solution.  As a matter
of fact, that just may be the universal solution to all problems!  My rig
won't power up... hey, remove the On/Off switch, and... problem fixed!
>
> After calling TenTec and receiving no help, I posted here.  Maybe I'm to
critical, but... when I read documentation as to the functioning of a piece
of equipment.... and it doesn't function as described, I look for answers.
Not using the function, is not a viable answer for me.  Wasting time sorting
through puffery is annoying, to say the least.
>
> I realize that membership here is free... however, it's a shame that some
are bent on making it worth nothing.
>
> Thanks to those that helped,
> 73
> Emil
> W9NM
>
>
> >>>
> > If you gentlemen come up with a set of control parameters
> > that allow the use of DSP NR with CW, please post your solution.
>
> If you operate CW with reasonably narrow bandwidths, DSP NR is largely
> superfluous, if not downright useless.  The most effective noise reduction
> tool in CW mode (any radio, not just the Orion/II) is the the bandwidth
> control.
>
> I know that's not the answer you're looking for, but it is the case.
> There's considerable discussion in the reflector archives on the subject.
>
> Grant/NQ5T
> <<<
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