[time-nuts] Very accurate phase measurement using nanoVNA-H4 HW: introducing the tinyPFA

[Erik Kaashoek]

For those that want to do very accurate phase and frequency 
measurements, but are not willing or capable to buy a PhaseStation or 
Timepod a new FW has been made available for the nanoVNA-H4 HW that 
converts it into a mix between a DMTD and PhaseStation.
Accuracy of phase measurements is better then 1e-12 / (Tau in seconds) 
and the device support sending the phase measurements over USB to 
programs like TimeLab or writing to an internal SD card for later analysis.

During testing and comparing to other frequency and phase measurement 
devices the tinyPFA outperformed conventional frequency counters and 
delivered phase measurements identical to a PhaseStation when used above 
the noise floor.

A wiki containing all the information for creating and using your own 
tinyPFA can be found here: https://www.tinydevices.org/wiki/
A support forum is available in case you have questions regarding the 
operation of the tinyPFA or ant to share results
As the FW is fairly new you can expect some bugs.

The nanoVNA-H4 HW does not have to be modified so after use as tinyPFA 
it can always be converted back into a VNA.