[TenTec] Noise Reduction Setting

[Gary Hoffman]

Bill,

One thing is for sure.  IF...IF.....all that the processor in the Orion does
is build a narrower bandwidth filter around the signal, then it follows as
the night follows the day that a person doing the same thing with the filter
bandwidth controls will be able to achieve the same result.

It further follows that the constant building and rebuilding that would be
done in qsk by such an automatic NR filter could easily lead to processing
artifacts.

If this is all Ten Tec is doing, I wish they would say so !

Now, on the other hand, the kind of processing I've been talking about (and
was led to believe is being done by Ten Tec...but who knows, maybe not) does
not take huge parallel processors nor does it involve latency of any serious
amount.  In the military applications for example, SAW processors (Surface
Acoustic Wave) handle this nicely, as do various hard wired ASICS.  The
latter are comparatively cheap.  Neither do much actual processing, as the
algorithm is pretty much hard wired in.

Less expensive auto-correlation type processors also exist.  It was these
latter devices that I thought were implemented in the Orion.

As you know, this information simply does not appear to be forthcoming from
Ten Tec.  They won't even say yes or no.  So...I'm left up in the air with
no way to be sure of the answer.  Anecdotal evidence, while often
interesting, is of little use in this area, as you know.

So...bottom line...It can be done...in my other life I have seen it done and
played with the devices professionally....I thought Ten Tec was doing
it....if they are NOT...then hell....just turn off the NR and squeeze down
the bandwidth controls.  We all know that works every time.

73 de Gary, AA2IZ


----- Original Message ----- 
From: "Bill Tippett" <btippett at alum.mit.edu>
To: <tentec at contesting.com>
Sent: Thursday, December 07, 2006 11:20 PM
Subject: [TenTec] Noise Reduction Setting


>
>
> AA2IZ wrote:
>
>  >Perhaps I am mistaken in believing that there is actually a DSP
processor
> employed in the Orion, or that they do actual DSP processing with it.  Ten
> Tec's deafening silence on this whole DSP issue is a glaring failure of
> communication, IMHO.  Hopefully we can get some factual feedback on these
> points (from Ten Tec that is).
>
>          Of course all DSP rigs have DSP processors, but
> the real issue is what kind of "processing" do they actually
> do?  To meet the minimal latency requirements for a QSK rig,
> I think the DSP only builds bandwidth filters.  In looking
> at the Timewave data sheet, it appears to me that it also
> simply builds filters.  What you were describing before is
> much more complex, using auto-correlation techniques, etc.
> like JPL does to enhance images from space.  The problem is we
> simply cannot do that in the near real time required by QSK...
> and JPL cannot do it in real time either.  I believe they
> replay a digital stream many times to help extract the signal
> from noise, consequently it's never real time.
>
>          In copying N2XE's weak signal beacon a few years ago,
> my brain did a simple version of auto-correlation.  Since the
> signal was repetitive, I got my brain synchronized with the
> timing to help build the 4 letter codeword one letter at a
> time, but this is a far different situation than when we
> are trying to decode a non-repetitive signal in real time.
>
>                                          73,  Bill  W4ZV
>
>
>


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