[Orion] Orion NR Function and Aurora-like Received CW Note

[Joe Giacobello]

I am a new Orion owner after having bought a used unit last week.  The 
unit was just repaired and upgraded with the latest hardware changes 
about three weeks ago.  All seems to be working well except all of 
sudden the received CW audio turned somewhat raspy on all bands.  I have 
a vague recollection of having seen references to this problem in 
previous posts before purchasing the rig.  If so, can anyone enlighten 
me as to the source of the problem?

While the NR function seems to work as described in the manual, I have 
comments and a question.  As I understand it, the NR function attempts 
to distinguish between noise and the desired signal and then 
automatically builds a filter window around the desired signal to 
minimize the noise and increase the S/N ratio.  It seems to me that when 
one attempts to enhance a weak signal in that manner, that automatic 
process would only be effective if the frequency were QRM-free.  In 
other words how is the processing able to distinguish between the 
desired (weak) signal and any interfering stations?  One argument might 
be that the processing only operates on signals exactly in the center of 
the passband.  Also, if one were able to eliminate QRM by narrowing the 
passband, then presumably there would be no problems.  On the other 
hand, in a simplex pileup the desired (weak) signal would be ignored by 
NR unless one were able to activate it when all QRM were absent.  Isn't 
this a serious limitation for an auto NR function vs the more common 
manual NR and signal peaking features of audio based DSP units such as 
the JPS NIR-12?  Do I have this right?  I'd be interested in hearing any 
comments on this topic.

Thanks and 73 de Joe