[time-nuts] Phase measurement performance assessment of 8405A vector voltmeter

[Erik Kaashoek]

The input to the 8405A inputs comes from a two channel DDS set to output 
two 10MHz signals 0.01 or 0.001 Hz apart to create a rotating phase with 
100 or 1000 seconds period. The output of the DDS has been assessed and 
its phase linearity over time is better then 1e-12
The  +/- 0.5 V phase output is sampled at 0.1 s interval with a 6.5 
digit multimeter. The +/- 0.5 V is translated to +/- 50 ns and input to 
Timelab.
The linear residue of a full rotation is calculated and appears to have 
a 3e-9 magnitude non linearity
Is this to be expected?
The ADEV @ 1 s of the 1000 s rotation is about 1e-11. Is this expected?
Can these values be used in a comparison with other phase measurement 
devices?
Erik.