Virgo Logbook

The first plot and its zoom shows the coherency between the B1s_PD1_Audio channel and some longitudinal photodiode Audio channels

according the LNFS 56MHz modulation depth: green 11dB, red 8dB, purple 5dB and blue 2dB :

all these Audio channels have a some coherency with the B1s_PD1_Audio channel
on SDB2_B1p_PD1_Audio, one can see that the coherency with B1s_PD1_Audio decrease with the 56MHz modulation depth lowering, to be close to zero with the lowest 56MHz modulation depth
for the others channels, the coherency with B1s_PD1_Audio decrease only when the 56MHz modulation depth decreases to 8dB and remains at the same level even if the 56MHz modulation depth decreases to lower values

The last plot and its zoom are related to the B4_PD1_56MHz magnitude and its correlation with the B4_PD1_Audio and B1s_PD1_Audio channels

the channel B4_PD1_56MHz_raw_mag is equal to the magnitude of the B4 beam demodulated at 56MHz before the demodulation noises mitigation
the B4_PD1_56MHz_mag is the magnitude after the demodulation noises mitigation
There is some coherency between the B4_PD1_Audio channel and the B1p_PD1_Audio one (blue rectangle)
there is no coherency between the B4_PD1_56MHz magnitude and the B1p_PD1_Audio channel (green rectangle)
there is some coherency between the B4_PD1_Audio channel and the B4_PD1_56MHz magnitude after the demodulation noises mitigation (red rectangle)
- This coherency remains at the same level regardless of the modulation depth of 56MHz.