Further investigation to study in which state the IMMT1 trans QPDs gets noisy. Fig. 1 is the spectrogram of K1:IMC-IMMT1_TRANS_QPDA2_DC_PIT_OUT_DQ, and Fig. 2 is K1:GRD-LSC_LOCK_STATE_N.

Fig. 3 shows some analysis of the behavior.

• The 20-30 Hz, 117 Hz, and 163 Hz bumps excite when the guardian state is ENGAGE_PRMI_3F.
• The 60 Hz, 120Hz, ... power-line-like peaks disapper after ISS.