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What is the origin of the “pseudonoise” shown in the 2nd screenshot? Thanks, Mike, K6DRY

Michael Reid
Michael Reid Member ✭✭
edited June 2020 in FLEX-6000 Signature Series
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Answers

  • Michael Reid
    Michael Reid Member ✭✭
    edited September 2017
    Thanks, Paul...let me add some more information:  
    1.  The two screenshots are 20 kHz different in width and are constant in appearance, the true noise level is -96.3 dBm and is constant, and the two screenshots can be reproduced by alternately changing the panadapter width from <= 220 kHz to >= 230 kHz.  There is no change in the audio signal heard or appearance of the waterfall.
    2.  A similar "pseudonoise" occurs on 80 meters, with a different antenna, but not on the 20 --> 6 meter bands.
    I summary, I cannot ascribe the "noise" to true noise, impulse or other.
    Any further ideas?
    Thanks, Mike, K6DRY
  • George KF2T
    George KF2T Member ✭✭✭
    edited February 2019
    Does it change with the WNB setting?

  • lriehlou812 .
    lriehlou812 . Member ✭
    edited September 2017
    Looks like my SDRPlay when I turn on my Panasonic Plasma TV.
  • Tim - W4TME
    Tim - W4TME Administrator, FlexRadio Employee admin
    edited September 2017
    Do you hear a relay click when you change the bandwidth of the panadapter?
  • Kevin
    Kevin Member
    edited July 2019
    I think Tim is giving a clue to the answer. When I approach 230 KHz width of the panadapter I hear a relay click. I think that removes the pre-selector or makes some other "wide open" change? At any rate, I see a noisier display going from one side of the relay click to the other side and I think that's normal.

    I think this is all normal and expected and sure someone will have a better explanation of why this occurs. I don't think this is showing you local noise or anything you need to troubleshoot or hunt down. All looks good at "normal" panadapter bandwidths and is only exposed after that relay click - at least in my case.

    73,
    Kev K4VD
  • K9SO
    K9SO Member ✭✭
    edited January 2019
    I can't tell from the screenshots if it appears in the waterfall or not. I spent many hours chasing down a similar "pseudo noise" that appeared in the main display but not on the waterfall. I eventually found this to be a display anomaly if you use the WEIGHTED AVERAGE setting when normal and low level noises are present. 
  • K9SO
    K9SO Member ✭✭
    edited January 2019
    I can't tell from the screenshots if it appears in the waterfall or not. I spent many hours chasing down a similar "pseudo noise" that appeared in the main display but not on the waterfall. I eventually found this to be a display anomaly if you use the WEIGHTED AVERAGE setting when normal and low level noises are present. 
  • Michael Reid
    Michael Reid Member ✭✭
    edited June 2020
    More info re my "pseudonoise" --

    1.  Tim...no relay click at > < 220 kHz...but a "click" is heard at > < 440 kHz as the "WIDE" indicator of the increased bandwidth filter kicks in...however, see #4 below for solution to the pseudonoise...probably a deep glich in the SDR software.

    2.  George...no change with WNB setting...

    3.  Paul...no changes with all house lights / motors / plasma TV on versus off...

    4.  Fred...THE SOLUTION!!!  "Waterfall Display" was set for "ON", and when switched to "OFF" all the pseudonoise disappeared, with no discernable change in the waterfall appearance...

    Thank you to all!  A very peculiar finding indeed!   Mike, K6DRY
  • Ken - NM9P
    Ken - NM9P Member ✭✭✭
    edited September 2017
    My experience has been that using weighted averaging emphasizes the peaks of sharply rising noise or signals. So it is actually showing noise that is present, but overemphasizes it. It is handy in certain situations, I.e. Weak signals on Six Meters. But if you have a lot of sharply peaked, but random noise, it will display a lot of spikes that obscure other signals, and they may not be removed with WNB because they are not highly correlated noise.

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