[TenTec] Basic question (especially NR operation)

[Joe Giacobello]

Rick, your description below about the NR performance on the Orion 
prompted me to go back to the Doug's and Scott's writeup on Weak Signal 
DXing, etc.  It was my original impression that the NR function in the 
Orion essentially made a comparison between the signal and noise in the 
passband and then established a tight window (filter) around the signal 
and, in so doing, minimized the noise:  "...DSP NR builds a bandpass 
filter to automatically reduce noise, it produces the same effect as 
manually selecting a very narrow DSP passband filter."  Based on their 
description, I concluded that for the NR to work properly the desired 
signal had to be present when NR is invoked, and if one tuned to a 
different signal that one would have turn off the NR and then turn it on 
again so it could adapt itself to the new signal and noise conditions.  
In other words, having the NR on continuously was not the way to use 
it.  Your successful experiences suggest that I may have gotten this 
wrong, but the write-up (in several places) leads me to believe 
otherwise.  I wonder if you and others would comment on this point?

On another front, I have compared my 1000MP vs. the Orion on weak signal 
reception (not high QRN conditions) and found that by manipulation of 
the RF gain, audio DSP and crystal filters on the MP,  weak signal 
readability is equivalent to the Orion.  Admittedly, it's a little 
easier to achieve the same readability with the Orion.

Also, despite Sinisa's recommendations to the contrary, I have been 
running my RF gain wide open and varying the AGC threshold setting 
(relatively easy with N4PY's software) to maintain band noise and QRN at 
an acceptable level.  Unlike him, I haven't really experimented with 
various combinations to see if this is really the best approach, but it 
seems to work reasonably well.

73, Joe

NJ0IP wrote:

>
>We first adjusted the AGC threshold pretty high (can't remember the setting)
>until the background noise decreased significantly.  This made an
>unbelievable improvement.  We compared it to the TS-850.  The 850 also
>showed S-7 on the meter and sounded just as the Orion had sounded before the
>AGC adjustment.  There was nothing we could tweak on the 850 to improve the
>sound.
>
>Next we turned on the Orion's NR and set it to about 4.
>
>The result was something similar to having turned on a squelch.  Well you
>could still hear a little audio, but basically the background was quiet.
>Then as we tuned across the band, the signals just popped up out of nowhwere
>(or so it seemed).  We made several comparisons to the 850 to check if all
>of this noise reduction was deteriorating the signal strength of the desired
>station, but it wasn't.  What it did was keep the desired signal's strength
>constant while dramatically reducing the noise.  As a result, the 850's
>performance came nowhere close to the Orion's.  Another league (minor
>league).
>
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