Signal mirrors all over the band.

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df1ech
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Signal mirrors all over the band.

Postby df1ech » Sat Oct 29, 2016 8:00 pm

Since today signals are beeing copied all over the place.
I also can hear several FM broadcast stations everywhere I tune and I can't get rid of this issue anymore. What could be wrong (look at the start and end of the band in schreenshot) ?

Image

The only thing that has been changed since YESTERDAY is that I placed my mini Whip on top of the Discone instead of below the cone.
Image

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g1hbe
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Re: Signal mirrors all over the band.

Postby g1hbe » Sat Oct 29, 2016 8:50 pm

Have you tried choosing another converter LO setting? If these FM stations won't go away no matter what you do, an outboard FM rejector is the only answer.

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Andy

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df1ech
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Re: Signal mirrors all over the band.

Postby df1ech » Sun Oct 30, 2016 8:30 am

It wasn't an issue in the weeks before at all. I have no strong stations nearby.
Also the signal duplicates at the start and the end of my screenshot are not FM signals, they are signals which are there only beeing duplicated to the left and right of them.


But I discovered that ALL issues that I thought where hardware related completely dissappear when using SDRConsole V3!
The erratic behavior is gone, the center spike does never appear and gives no issues anymore, crackling QRM is gone, distortion in audio on stronger signals in the single side band is gone and all signal mirrors are gone.

So now I'm confused and don't know where to start looking anymore!

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DanubeBCL
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Re: Signal mirrors all over the band.

Postby DanubeBCL » Mon Oct 31, 2016 5:46 pm

Are you using a noise blanker which is adjusted very "tight"?
Noise blankers sometimes produce "ghost" signals when there are strong signals in the passband.
Just a guess.
73, Heinrich

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df1ech
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Re: Signal mirrors all over the band.

Postby df1ech » Mon Oct 31, 2016 6:10 pm

Juist the NB option enabled and set to NBN but it doesn't seem to be doing much as I get no difference between on and off. I use no external filters except the galvanic separation in the power feed unit for the whip.

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DaveB
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Re: Signal mirrors all over the band.

Postby DaveB » Mon Oct 31, 2016 10:14 pm

In the SP Window click on the ADV button (just to left of the PLAY! button) and check whether the DC/IQ button has been unchecked (dark instead of white). This would be one cause of the mirror signal/DC spike symptoms you report. The centre spike would then cause distortions to centre frequency signals etc - I just confirmed this - but only on broadcast FM.

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df1ech
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Re: Signal mirrors all over the band.

Postby df1ech » Mon Oct 31, 2016 11:28 pm

the button is checked :) but you can see my settings in the screenshot in the OP as i have all available windows open :)

http://www.krankimkopf.net/uno.jpg

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NN4F
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Re: Signal mirrors all over the band.

Postby NN4F » Fri Nov 04, 2016 3:29 pm

Are you getting the same with the NB turned OFF??

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df1ech
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Re: Signal mirrors all over the band.

Postby df1ech » Fri Nov 04, 2016 4:53 pm

well, yes, but it must be definitely something to do with the software as in sdrconsole and sdr# I have no such issues at all.

Also different decimation give different results and changing decimation from 16 to 8 and back to 16 also changes the result .

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