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Need help with lots of duplicate signals

Posted: Wed Jan 13, 2016 7:04 pm
by mesh
I am using SDRPlay (latest drivers) with SDR Console (latest version). I have about a 40 to 50 foot long wire connecting to a coax (10 ft) that connects to the SDR Play.

This is working well, but I am getting a lot of duplicate signals. For example:

Image

You can see my settings in the screenshot:

ACG On : Fast
LNA Gain Threshold : 59 db
Gain Reduction : 0 db
Visual Gain: -25 db
LO Mode: 168 MHz

Does anyone have any suggestions or input on what I can do to reduce the duplicate signals? Any input on my gain settings? (Any tweaks to Gain Reduction and visual noise leads to an increase in signal noise).

I am still trying to get an understanding of what all of the gain settings do, so I realize I may just be doing something really stupid.

Thanks for any input...

mike

Re: Need help with lots of duplicate signals

Posted: Wed Jan 13, 2016 10:31 pm
by Tech_Support
Hi Mike,
With 0dB of gain reduction, you have the receiver at maximum gain. This will overload your receiver. Try starting with about 50 dB of gain reduction as a starting point an tweak from there. With the LNA gain threshold of 59 dB, you LNA will be on (at its max gain setting) until the overall gain reduction goes above 59 dB, so you will still get decent noise performance with 50 dB of gain reduction.

I hope this helps.

Sincerely

SDRplay Tech_Support

Re: Need help with lots of duplicate signals

Posted: Wed Jan 13, 2016 10:57 pm
by mesh
Try starting with about 50 dB of gain reduction as a starting point an tweak from there.
Thanks. If I reduce the gain at all, then the noise goes way up and the waterfall is overwhelmed. See attached.

Image

Even smaller increments adds too much noise.

Although, maybe it is just my visual settings for SDR Console. If I move the control on the right of the water fall, it I can clean up the waterfall.

Thanks for the input. I think I understand what is going on and how to fix it. Plus, I now have a lot more room to move around settings.

Thanks again...

mike

Re: Need help with lots of duplicate signals

Posted: Fri Jan 15, 2016 2:28 pm
by rgood123
In short, had the same interfence with a longwire this is what i did to reduce the EMI, harmonics.
What worked:
Cure.png
Cure.png (189.83 KiB) Viewed 12680 times
What didn't work:save your money
Active antenna Preselector-just amplified the problem.
USB Isolator ADUM4160-data transfer rate to slow for sdr .