J. Kissel, K. Venkateswara

Krishna and I completed the installation of the H1 EX Beam Rotation sensor today by inserting the analysis laptop's output (via a USB DAC NI-6343). The tilt signal channel, H1:ISI-GND_BRS_ETMX_RY_OUT_DQ (fs = 256 [Hz]) is filtered to produce a calibrated tilt signal in [nrad]. Pictures and data to come!

Raw data is output with a very-low frequency high-pass to limit the range of what goes into the ADC
2 zeros @ 0 [Hz], 2 poles @ 1 [mHz]

Once in the aLIGO DAQ, there are two calibration filters,
FM1
Rotation sensor gain calibration
Filter File: /opt/rtcds/userapps/release/isi/h1/filterfiles/H1ISIETMX.txt
Filter Bank: (FM1) H1:ISI-GND_BRS_ETMX_RY_Name00
Filter Name: "ct2nrad"
3.5e-6 [rad/pixel] * 1 [pixels/V_sing] * 1/2 [V_sing / V_diff] * 40/2^16 [V_diff/ct] * 1e9 [nrad/rad] =  1.0681 [nrad/ct]

FM2
Rotation sensor pendulum response inversion
Filter File: /opt/rtcds/userapps/release/isi/h1/filterfiles/H1ISIETMX.txt
Filter Bank: (FM1) H1:ISI-GND_BRS_ETMX_RY_Name00
Filter Name: "ct2nrad"
2 complex zeros at 8.8 [mHz], with a Q of 100
2 poles at 0.001 [Hz] to roll off inversion
Normalized to 1 at high frequency
zpk([4.4e-05+i*0.00879989;4.4e-05-i*0.00879989],[0.001;0.001],1,"n")gain(77.4401)