Chiara, Jenne.

Today we took some measurements of PRCL with LSC_DIFF on and off for PRM M1. The CPS_DIFF was always ON. A couple of things to take note of:

• To notice that, for PRM, the gain of LSC_DIFF must be with minus sign.
• The LSC filter (see block diagram in 53160), is built in this way:

LSCdiffFiltzpk = zpkgf(0,[0.05,0.05],1,0.005);

LSCboost=zpkgf([0.0878904+i.*0.0817023,0.0878904-i.*0.0817023],[0.0440496+i.*0.111623,0.0440496-i.*0.111623],1,1000);

LSCdiffFiltzpk = 2*LSCdiffFiltzpk*LSCboost;

The plot in attachment 1 shows the ratio between ON and OFF measured conditions (light blue) and expected conditions (black): probably we need a higher gain in the measurements.

Attachment 2 and 3 shows the crossovers between M1 and ISI, and M1 and M3, and the distribution filters. If you can notice something unusual in these plots around 0.7 Hz, the reason is that we did not change the M1 and M3 filters before applying  LSC_DIFF: probbaly, in future, we will change those filters to roll off the M1 filter more steeply.

Last attachment shows the difference between PRCL open loop gain when we apply ISI offloading (red trace) with respect to the PRCL open loop gain withount ISI offloading (blue).

FUTURE WORK:

• Investigate why DARM got worse (alog 53433)
• Increase the LSC offloading gain to try to match the simulations
• Try also SRCL