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Re: Best way to use NB and NR?

Posted by Bob K6UJ on Sep 30, 2011; 4:48am
URL: http://elecraft.85.s1.nabble.com/Best-way-to-use-NB-and-NR-tp6844498p6846464.html


Wow Don,  great explanation !

Bob
K6UJ




On Sep 29, 2011, at 8:51 PM, Don Wilhelm wrote:

> The K3 noise blanker, and in fact any noise blanker works by producing
> "holes" in the receive path.  That is what blanking means - if an
> impulse is detected, it shuts off the receive path for a specified
> period of time.
>
> That will not "take away" from the reception of faint signals, but if
> combined with gaps in the received signals because of impulse events
> occurring at the receiving station, it may make the copy of faint
> signals difficult because of the blanks in the received data stream.
>
> In my opinion, it should only be used when necessary, not all the time.  
> If you have constant static pulses or automotive ignition noise or
> distant lightning surge problems at your QTH, then it may be beneficial
> to run the NB at all times, but if you do not need it, keep it off.  
> Remember that the NB responds to impulse noise - it will not be
> effective in reducing slow rise time noise like atmospheric noise or
> power-line induced noise.  NB needs a fast rise time to be effective.
>
> NR is a different animal altogether.  It will reduce or eliminate things
> like atmospheric noise or power line noise - it works on correlation
> principles.  That means is it is normally quiet while it looks for what
> might be a valid signal.  When it finds something that appears to be a
> valid signal, it builds a filter around it and sends that result to the
> K3 audio.  What it looks for is highly dependent on the parameters set
> for the K3 NR algorithm as well as your local noise.  There are several
> settings provided for in the menu.  Do a little experimenting with your
> chosen mode and local noise situation until you discover what works best
> for you.  The settings for CW will likely not be good for SSB.  Try the
> settings to find which works for your particular situation.  This is not
> a case of "one size fits all", customize it to your particular noise
> source.   With NR on, the desired signal should be enhanced, but really
> weak signals may be at or near the noise level, and may not appear as a
> valid signal, giving the appearance that weak signals may be covered up
> and not detected.  I suggest (after experimenting) that you normally run
> with NR turned off, but turn it on if the situation warrants it.
>
> 73,
> Don W3FPR
>
> On 9/29/2011 12:15 PM, tomb18 wrote:
>> Hi,
>> I was wondering if anyone could give me some hints as to the best way to use
>> the NB and the NR?
>> Most of the time I use the nr and there seems to be little effect of the nb
>> (maybe one-two s units?)  Does the nb take away from faint signals?  If not
>> should I always just use it?
>>
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