TinyPFA is firmware from Erik Kaashoek for NanoVNA-H4 hardware for accurate measurement of oscillator and clock source stability.
This article documents an experiment to measure the Allan Deviation of several sources:
- Trimble Thunderbolt GPSDO;
- Motorola R2009D service monitor; and
- Rhode & Schwarz SML01 signal generator.
So, to make a two way comparison or three sources, there are C(3,2)=3 difference combinations, and a fourth test to document the instrument noise floor (connect the same source to both inputs).
TinyPFA and Timelab were used to make the measurements.
The GPSDO reference used was a Trimble Thunderbolt GPSDO which is locked.
The plot above shows the noise floor, and the comparison of each of the reference sources.
This was an excellent combination for performing the tests.