DSP no help for QRN - atmospheric noise

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  • Updated 5 years ago
With atmospheric noise today at S5-7, I looked to DSP to help with noise reduction, NR, but alas, at any setting, no help. NB reduced some hiss but did not help readability. Finally ANF did nothing at all. Guess I was expecting more here, but I realize atmospheric noise if a tough one to eliminate without introducing distortion.
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Barry Isseks

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Posted 5 years ago

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Al / NN4ZZ

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Hi Barry,
Did you mean ANF or APF?

ANF  (Auto Notch Filter) 

APF (Audio Peaking Filter from the DSP tab)

I think the two terms get accidentally mixed up a lot.  Typo, etc. 

But since they are both used in noise reduction it could be either one.


Regards, Al / NN4ZZ  
al (at) nn4zz (dot) com
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Barry Isseks

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Indeed you are right.. ANF was a non-sequitor here. NR and NB was the thrust of the post. Thanks
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Al / NN4ZZ

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Barry,
Got it.  And APF does also help with the S/N a little if you are in CW mode.  It could do more and hoping we see that in V1.5.

https://community.flexradio.com/flexradio/topics/ssdr_v1_2_apf_could_use_more_gain_it_seems_diminish...

Regards, Al / NN4ZZ  
al (at) nn4zz (dot) com  
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Tom Warren

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Al,
I've now taken some time to work with the APF, AGC-T and various filter settings on the lower HF bands ( 20,30,40M) and in my opinion the APF doesn't seem to result in the signal popping out of the noise nearly as well as on 6 and 2M. Maybe that's due to the differences between VHF's colder temp. and HF's warmer temp. and how SSDR treats that difference.   Tom W4TMW
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Jim Gilliam

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It's like trying to legislate a cure for poverty. It is impossible to cure social ills with limited resources and too many peopole. Likewise, no magic can add more signal. Unless we get into auto-correlation but that takes time and many scans to differentiate between signal and noise.
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k3Tim

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As we know, we're all expecting improvements in this area come S-SDR 1.5.nnn time frame.  Be that as it may I have experienced the NB knocking down certain impulse type noise very well.  Summer type QRN from storms not so much.  Using the FRS operational method of turning down the AGC threshold helps.

ANF - AutoNotch Filter - not for natural QRN.

On latest releases the NR (set at low value) is knocking down hiss type noise, especially on 10-meters very effectively.

Have you tried the APF? (not for the QRN of course)  It helps for CW work. I have an TT-Omni 6+ that has similar function and the CW note jumps out of the noise level at you - it's remarkable.  On teh 6500, APF works but seems not as much as the TT.

Best 73's,

k3Tim