Interesting noise spectra.

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!

George Molnar, KF2T, Elmer

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curious

Posted 3 years ago

3 years ago

AH0U

354 Posts
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That is an interesting screen shot showing the call sign too... What software is that??

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3 years ago

David Decoons wo2x, Elmer

1490 Posts
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Looks lie SmartSDR for IOS on either iPad or iPhone

Dave wo2x

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3 years ago

AH0U

354 Posts
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Nice

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3 years ago

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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3 years ago

KY6LA - Howard, Elmer

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That is Dogparksoftware for Mac ...Noi SmartSDR for iOS.

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3 years ago

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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3 years ago

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 !