SDRplay as a direct circuit Spectrum Analyzer?

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SDRplay as a direct circuit Spectrum Analyzer?

Postby DENM » Wed Feb 22, 2017 2:27 am

When you set aside demodulation, what about a somewhat simpler use of this system?

Maybe a crazy idea, and SDRplay management may not condone, but would/could it make sense with appropriate input attenuation (and perhaps) impedance matching, to use SDRplay plus as a tool for direct spectral measurement of a signal chain in radio or filter circuit design?

Yes, one would have to be careful, and could blow out the SDRplay hardware, and maybe even your PC if you don't watch out, but it should work, right?

Thanks, DENM
Last edited by DENM on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
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Posts: 103
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Re: SDRplay as a direct circuit Spectrum Analyzer?

Postby someYguy » Mon Feb 27, 2017 5:47 am

Not crazy at all, and you can indeed use your SDRPlay RSPx as a good test instrument. See my posts about this here:

And here:

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Re: SDRplay as a direct circuit Spectrum Analyzer?

Postby Retika » Sat Feb 16, 2019 7:11 am

Spektrum is a popular spectrum analyzer program that is used with RTL-SDR dongles. It is based on the command line rtl_power software and is compatible with both Windows and Linux. Thanks to it's easy to use GUI it is an excellent piece of software for scanning and determining where active signals exist, or for measuring filters and antenna SWR with a noise source.
The changelog reads:

2 Cursors for Frequency axis.
2 Cursors for Amplitude axis.
Absolute and differential measurements with cursors.
Zoom functionality of the cursors' defined area (gain + frequency).
Mouse Wheel Gain adjustment on the graph (Top area for the upper, low area for lower).
Mouse Wheel Frequency adjustment on the graph (left area for lower frequency, right for upper).
Mouse Wheel in the center of the graph performs symmetric zoom in/out.
View/settings store/recall (elementary "back" operation, nice for quick zoomed in graph inspection).
Right-click positions primary cursors.
Right Double Click positions primary cursors and moves secondary out of the way.
Left Double Click zooms area defined by cursors (Amplitude + frequency).
Left Mouse Click and Drag on a cursor moves the cursor.
Middle (mouse wheel) Double Click resets full scale for Amplitude and Frequency.
Middle (mouse wheel) Click and Drag, moves the graph recalculating limits accordingly.
Reset buttons to Min/Max range next to Start and Stop frequency text boxes.
The cursor on/off checkbox now operates on all 4 cursors.
ZOOM and BACK buttons.
Filled-in graph option (line or area).
Display of frequency, Amplitude, and differences for all cursors.
Modified: Button layout.
Fixed: Save/Reload settings on exit/start. IMPORTANT: delete the "data" folder from the installation location if you have it.
Filling in graph option (line or area).
Last edited by Retika on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
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