Hi have set up the arm transmssion QPD monitor for storing the test mass resonant mode signals from 14.8-15.8kHz in 2kSa/sec channels: 
H1:SUS-ETMX_PI_DOWNCONV_DOWNCONV1_DEMOD_I_OUT_DQ 
H1:SUS-ETMX_PI_DOWNCONV_DOWNCONV2_DEMOD_I_OUT_DQ 
H1:SUS-ETMX_PI_DOWNCONV_DOWNCONV3_DEMOD_I_OUT_DQ 
H1:SUS-ETMX_PI_DOWNCONV_DOWNCONV4_DEMOD_I_OUT_DQ 
represent ETMX QPD A segments 1-4 downconverted such the 0Hz represents 14.8kHz and 1kHz represents 15.8kHz.