I closed the WFS loops and measured the transfer function from IN2 to IN1 testpoints on the WFS1_PIT filterbank.
We looked at the filter shape consisting of
1) Integrator: zpk([0.8],,0.8,"n")
The combined filter shape (along with an added pendulum filter, zpk([ ],0.8,1,"n") ) is given below
The OL Transfer function measured for WFS1_PIT loop is
The blue reference is a measurement without the third "45 deg" filter in the list above. Without it the UGF is around 1.5Hz and increasing the gain results in additional noise from the servo bump seen in the earlier elog . With it the UGF is around 3Hz.
The supression of the error signal is shown here
The other WFS loops are expected to have a similar behaviour with the exception of the MC2 QPD channels. I will measure their OLTF shortly and then proceed with the inclusion of the QPD sensors into the WFS system.