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Noise reduction algorithms

Posted: Fri May 01, 2020 6:35 am
by iu4ivr
Good morning,
i approached Flex 5000 and after having found an appropriate station setup i can say i'm really happy with this system.
I spent many hours in the past listening to BHI noise reduction stuff, actually i can't get the same filtering feeling with PowerSdr NR algos even playing with custom parameters.
I was wondering which kind of NR strategy is used in PowerSdr.
Thanks in advance.
Matteo.

Re: Noise reduction algorithms

Posted: Sat May 02, 2020 6:45 pm
by ke9ns
I haven't looked at the DSP code for the NB, NR stuff yet.
i have noticed that if the DSP buffer is set to 4096, the NR/ANF doesnt work well. Its much better with 2048 DSP buffer.(setup->DSP->Options)

The NB works for me when I have electrical noise (usually in the winter), but it has 1 issue, where it deactivates/activates with a very strong signal (outside your passband). So if I am on 3630 SSB but can see a strong CW signal (+20) on 3500, the NB will work perfect until the strong CW signal starts tapping.

Darrin ke9ns

Re: Noise reduction algorithms

Posted: Wed May 06, 2020 10:06 am
by WS0I
I have found that the NR really isn't a set once and forget it. I have adjusted this many times, and what seems to work reasonably well one evening, will be totally unsuitable the next evening. I have also found that the even with light settings the audio distortion and dsp artifacts are very unpleasant on the ears.

I have no idea if the NR is in the audio chain or the IF chain. The NB, and NB2 work fine here however I have found you can not really stray to far from the default settings or it will start causing signal distortion and spurs.