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Interesting noise spectra.

George KF2TGeorge KF2T Member ✭✭✭
imageimage Opinions? Bit of a head scratcher for me. Broadband noise (thankfully not continuously) with a pronounced dip where I expect the band filter to be... or is it? Same with tuner in or out, even on different antenna (different levels, of course). Not so much interested in the noise itself, but why/how the band cutout works. Fascinating stuff!


  • AH0UAH0U Member
    edited June 2019
    That is an interesting screen shot showing the call sign too... What software is that??
  • David Decoons, wo2xDavid Decoons, wo2x Member ✭✭✭
    edited June 11

    Looks lie SmartSDR for IOS on either iPad or iPhone

    Dave wo2x

  • AH0UAH0U Member
    edited June 2019
  • Mike AustMike Aust Member ✭✭
    edited September 2016
    Yes, I have seen this before, you just found the band edges of the band filter for 20meters 
  • KY6LA_HowardKY6LA_Howard La Jolla, CA. Paris and Sablet FranceMember ✭✭✭
    edited January 2017
    That is Dogparksoftware for Mac ...Noi SmartSDR for iOS.
  • George KF2TGeorge KF2T Member ✭✭✭
    edited February 2019
    Well, now that we've confirmed I'm using DogPark SDR (highest praise to developer Don)... Still wonder why what appears to be the band filter effectively removes some of the noise level? With the noise absent, I see essentially a flat (within the expected characteristics of my antenna) noise level over the same spectrum.  

    Unless the noise itself is lower around the ham band, it's odd...

  • Mike AustMike Aust Member ✭✭
    edited September 2016
    Besides the Passband Filter I suspect a different algorithm is in place for the 
    in-band ham band passband is taken into place & consideration (sampling versus BW, etc )
    Only the guys at Flex would know !
  • Gerald-K5SDRGerald-K5SDR FlexRadio Employee ✭✭
    edited April 2019
    That looks like Broadband over Power Line (BPL) with the ham band notched.
  • George KF2TGeorge KF2T Member ✭✭✭
    edited February 2019
    Thanks, Gerald. Widening out the display, I can see other gaps, too. Not always aligned with the ham bands. Looks like I need to do some DF-ing. 
  • K1UO - LarryK1UO - Larry Member ✭✭
    edited December 2017

    Hi George,  Have you tried posting this to the RFI Reflector?  Many savvy people on there that may be able to help identify this.


    and lots of info in the Archives at: http://lists.contesting.com/_rfi/

  • George KF2TGeorge KF2T Member ✭✭✭
    edited February 2019
    Thank you, Larry.

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