This Spectrum Analyzer plugin works with the IIO Oscilloscope. You use the latest version if possible.
The plugin is made available by IIO Oscilloscope only when one of the following boards is detected:
The AD-FMComms3-EBZ is more targeted for wider tuning ranges than the other boards enumerated above which make it the best candidate to be used with this plugin.
The “Spectrum analyzer” measures the magnitude of an input signal versus frequency within the full frequency range of the instrument (in this case the PCB). For the AD-FMCOMMS3-EBZ that is 70 MHz - 6000 MHz (the limits of the AD9361).
This is not meant to be the worlds best spectrum analyzer, but an example of how to use the fast lock feature of the AD9361, with a small contrived example (which is multi-threaded, so it does actually get adequate performance).
The overall method uses is known as a Hybrid SuperHeterodyne-FFT. The technique used is to combine sweeping the LO and using FFT analysis on the captured signals for consideration of wide and narrow spans. This technique typically allows for faster sweep time.
One benefit of digitizing the intermediate frequency is the ability to use digital filters, which have a range of advantages over analog filters such as near perfect shape factors and improved filter settling time. Also, for consideration of narrow spans, the FFT can be used to increase sweep time without distorting the displayed spectrum.
To try to minimize blind time, we wrote a multi-threaded application, which spawns a few different threads to capture and process the FFT data, to try to do as much in parallel as possible. While data is being processed (FFT), we are changing the LO for the next capture.
If you have questions, please ask on EngineerZone.