jankae
Phase Frequency Analyzer option
Summary
Phase Frequency Analyzer mode using already existing VNA hardware.
There is an already existing tinyPFA, but I think the measurement accuracy can be improved with the libreVNAs hardware: https://www.tinydevices.org/wiki/pmwiki.php?n=TinyPFA.Accuracy
Hardware for tinyPFA is the nanoVNA-H4, which uses temp-sensitive mixers (SA612AD*) and an audio codec as its ADC (https://www.ti.com/lit/ds/symlink/tlv320aic3204.pdf)
*source: https://github.com/hugen79/NanoVNA-H/blob/F303_ChibiOS_18/doc/Schematic_NanoVNA-H4_2_1.pdf
Paths to implement it
There is an implementation on the nanoVNA-H4 where the MCU has been reflashed to work as a phase frequency analyzer:
https://www.tinydevices.org/wiki/pmwiki.php?n=TinyPFA.Homepage
Maybe the MCU code can be rewritten on the LibreVNA to support this as well.
Extra information
I'd be happy to look this & contribute if you think the hardware can support PFA mode
I agree, it is likely possible to add PFA as a feature. I am not really familiar enough with that measurement technique to judge whether the hardware would support better accuracy than with the nanoVNA.
But I also think the implementation is not that easy. You definitely have to add things in the GUI and the firmware. Depending on the measurement method, you will also have to adjust the FPGA configuration. Certainly possible, but not exactly a quick weekend project.
I am going to be honest: this feature is not very high on my list. I am happy to support you if you want to take this on and should I ever run out of ideas for the LibreVNA I might even implement it myself. But that is most likely not happening within the next weeks/months.
Closing for now because I have no plans to implement this anytime soon. If someone wants to take this on just let me know and I will provide some pointers (but you will need to be comfortable with MCU and FPGA development already)