[Orion] V2.059d Vs. v1.373b5 Noise Reduction Code + My experiences with 1.373b5

[Joe Giacobello]

Sinisa, I admit to not having referred to the manual in quite some time, 
but I just went to p. 46 in both the 2003 and 2005 manuals and could not 
find the phrase you quoted.  I looked over that page and neighboring 
pages several times.  Maybe my mind is acting like rejection filter, but 
I couldn't find it.  Nevertheless, the search resulted in my reviewing 
the section on weak signal reception and that was a worthwhile exercise.

As far as "correlated Schotte noise" is concerned, I apparently did not 
correctly remember the spelling of Schott's name, and Schotte would seem 
to be another variation of the same German root, and that's the spelling 
that came to mind at the time.  (I also admit to having a penchant for 
pronouncing - and now adding one where none exists - the final "e" in 
German nouns after I overheard Claudia Kohde Kilch mumble "Scheisse" 
during a match at the US Tennis Open and discovering that I had been 
pronouncing it wrong all these years.)

As I understand DSP noise reduction, it focuses on that portion of a 
given signal that is continuous and, more or less, invariant in 
amplitude and occurrence, attenuates it and allows the more variable 
data signal pass.  Such noise, if my memory serves, is referred to as 
correlated.  Schott noise, again if my memory serves, is continuous 
noise associated with the movement of electrons and is always present in 
conductors except at absolute zero.  Aside from misspelling his name, I 
also should have added "and the like."  I admit that my readings on DSP 
are not fresh in my mind nor up to date, and if I got it wrong then I 
accept the scarlet "mea culpa."

I replaced 2.059d with 1.373b5 last night and the change in performance 
was both dramatic and negative.    There was an enormous increase in RF 
gain, which was further increased when invoking NR.  I tried 
manipulating the Threshold, Decay, Attenuator and NR setting without 
much improvement.  To make 40M CW even marginally listenable, I had to 
use 12 dB of attenuation.  The NR seemed to act properly with the 
attennuation.  The Threshold setting seemed to have no effect and there 
seemed to be a non-linearity in the RF gain control.

The higher RF gain was also evident when using N4PY's sweep routine, 
which uses the sub receiver to sweep with the RF gain at maximum.  The 
band noise base line was as high as I've ever seen it.  I switched to my 
FT-1000MP for comparison and the improvement was enormous. What seemed 
to be a irritatingly noisy band on the Orion was pleasantly serene on 
the MP.  I have since returned to 2.059d.

What is especially disturbing is that I know others are using 1.373b5 
with good results.  There have been other occasions when my observations 
of the Orion's behavior have differed substantially from those of 
others.  It makes me think that I have some kind of hardware problem in 
my unit, but I'm really not sure at this point.

73, Joe
K2XX

Sinisa Hristov wrote:
> Joe Giacobello wrote:
>
>  
>   
>> it seems that the NR functions more as a narrow bandpass filter
>>     
>
> Even the Manual says so on page 46:
>
>   "Because the DSP NR builds a bandpass filter to automatically reduce
>    noise, it produces the same effect as manually selecting a very narrow
>    DSP passband filter."
>
>
>   
>> than a correlated Schotte noise attenuator.
>>     
>
> What would that be?
>
>
> 73,
>
> Sinisa  YT1NT, VE3EA
> _______________________________________________
> Orion mailing list
> Orion at contesting.com
> http://lists.contesting.com/mailman/listinfo/orion
>
>
>