[Kamiizumi, Aoumi, YamaT]

This is a series work of following posts.
klog#24725 (IY), klog#24726 (IX), klog#24919 (EY), klog#25011 (EX),
klog#24916 (BS), klog#26129 (SR3), klog#26230 (SRM),
klog#25009 (PR2), klog#25886 (PR3), and klog#26205 (PRM).
 

Abstract

Because of the Dolphin trouble, DAC noise measurement for SR2 was postponed in klog#26384. So this work is just a re-try work for the first time in 4 months.
For all actuators, 1 or 2 stages of de-whitening filters are enough to avoid being limited by DAC nose.
We competed the DAC noise measurements for Type-A, Type-B and Type-Bp.
 

Details

We measured the DAC noise for TM and IM coil actuators at AI output and at the monitor port of satellite boxes, which is same procedure as measurements for other suspensions.

TM (Fig.1-4)
DAC channel for H2 coil has too loud DAC (or AI) noise below 1kHz. But this noise can be mitigated by 1 stage of de-whitening filter and 1 stage of de-whitening filter for TM is always enabled. So it seems to be negligible in practical use.

IMV (Fig.5-7)
Two stages of de-whitening filters are always enabled for vertical coils and there is no improvement by enabling the 3rd stage. So two stages seem to be enough for mitigating the DAC noise. For all 3 vertical coils, 0.2Hz peak can be seen at the monitor port of the satellite box. Because this peak couldn't be found on the AI output, it may be caused by the reflection from coils, cross-talk with OSEM sensor signals on the satellite box, and so on.

IMH (Fig.8-10)
Two stages of de-whitening filters are always enabled for vertical coils and there is no improvement by enabling the 3rd stage. So two stages seem to be enough for mitigating the DAC noise. There was no strange behavior on DAC noise.