Welcome to the new FlexRadio Community! Please review the new Community Rules and other important new Community information on the Message Board.
If you are having a problem, please refer to the product documentation or check the Help Center for known solutions.
Need technical support from FlexRadio? It's as simple as Creating a HelpDesk ticket.

DSP no help for QRN - atmospheric noise

Barry Isseks
Barry Isseks Member ✭✭
edited May 2020 in SmartSDR for Windows
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.


  • Al_NN4ZZ
    Al_NN4ZZ Member ✭✭✭
    edited May 2019
    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

  • Jim Gilliam
    Jim Gilliam Member ✭✭
    edited September 2018
    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.
  • k3Tim
    k3Tim Member ✭✭✭
    edited May 2020
    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,

  • Barry Isseks
    Barry Isseks Member ✭✭
    edited July 2015
    Indeed you are right.. ANF was a non-sequitor here. NR and NB was the **** of the post. Thanks
  • Al_NN4ZZ
    Al_NN4ZZ Member ✭✭✭
    edited December 2016
    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.


    Regards, Al / NN4ZZ  
    al (at) nn4zz (dot) com  
  • Tom Warren
    Tom Warren Member
    edited April 2015
    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

Leave a Comment

Rich Text Editor. To edit a paragraph's style, hit tab to get to the paragraph menu. From there you will be able to pick one style. Nothing defaults to paragraph. An inline formatting menu will show up when you select text. Hit tab to get into that menu. Some elements, such as rich link embeds, images, loading indicators, and error messages may get inserted into the editor. You may navigate to these using the arrow keys inside of the editor and delete them with the delete or backspace key.