Noise reduction algorithms

Installation questions, Setup, and general information not covered in the other sub-forums
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iu4ivr
Posts: 1
Joined: Fri Apr 24, 2020 2:00 pm

Noise reduction algorithms

Post 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.
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ke9ns
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Location: Illinois, North West Suburbs
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Re: Noise reduction algorithms

Post 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
Creator of PowerSDR KE9NS v2.8, based on the Flex Radio PowerSDR v2.7.2 software.
Flex-5000, LDMOS and Titan Amps, G5RV, and Mosley TA-33 Junior
WS0I
Posts: 2
Joined: Sun May 03, 2020 5:58 pm
Location: Wamego, KS

Re: Noise reduction algorithms

Post 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.
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