Interesting noise spectra.

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  • Updated 3 years ago



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!
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George Molnar, KF2T, Elmer

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  • curious

Posted 3 years ago

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AH0U

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That is an interesting screen shot showing the call sign too... What software is that??
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David Decoons wo2x, Elmer

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Looks lie SmartSDR for IOS on either iPad or iPhone


Dave wo2x

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AH0U

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Nice
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Mike Aust

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Yes, I have seen this before, you just found the band edges of the band filter for 20meters 
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KY6LA - Howard, Elmer

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That is Dogparksoftware for Mac ...Noi SmartSDR for iOS.
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George Molnar, KF2T, Elmer

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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...
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Mike Aust

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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 !
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Gerald - K5SDR, Employee

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That looks like Broadband over Power Line (BPL) with the ham band notched.
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George Molnar, KF2T, Elmer

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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. 
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K1UO - Larry

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

http://www.contesting.com/FAQ/rfi

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


(Edited)
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George Molnar, KF2T, Elmer

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Thank you, Larry.