Virgo Logbook

AdV-DAQ (Data Acquisition and Global Control)

masserot - 16:05 Thursday 22 August 2019 (46741)

EOM Demodulation VGA gain set to LowGain

This morning the setup on the EOM digital demodulation for the 6MHz, 8MHz, 22MHz and the 56MHz has been updated by ajusting the VGA gain to use the LowGain mode instead of HighMode mode.

Configuration file: /virgoData//VirgoOnline/LNFS_dbox_rack.cfg

#DBOX_DEMOD_CHANNEL DAQ_EOM_Out0 0 0x84 1.0 0.0 V "NC" # HighGain
DBOX_DEMOD_CHANNEL DAQ_EOM_Out0 0 0x1C 1.0 0.0 V "NC" # LowGain

#DBOX_DEMOD_CHANNEL DAQ_EOM_Out1 1 0x88 1.0 0.0 V "NC" # HighGain
DBOX_DEMOD_CHANNEL DAQ_EOM_Out1 1 0x39 1.0 0.0 V "NC" # LowGain

#DBOX_DEMOD_CHANNEL DAQ_EOM_Out2 2 0x88 1.0 0.0 V "NC" # HighGain
DBOX_DEMOD_CHANNEL DAQ_EOM_Out2 2 0x1C 1.0 0.0 V "NC" # LowGain

#DBOX_DEMOD_CHANNEL DAQ_EOM_Out3 3 0x84 1.0 0.0 V "NC" # HighGain
DBOX_DEMOD_CHANNEL DAQ_EOM_Out3 3 0x1C 1.0 0.0 V "NC" # LowGain

The operation was done between 2019-08-22-08h25m55-UTC and 2019-08-22-09h23m16-UTC.

Comments to this report:

Paoletti - 12:14 Friday 23 August 2019 (46750)

Using the data of the temporary installation for the RAM noise measurement on 8MHz and 56MHz, we can see that the coherence between these signals (ENV_RAM_8MHz_moni) and the ones available reading the EOM output monitor (DAQ_EOM_8MHz_raw_mag) is near zero.

This confirms that the ADC that monitors the EOM outputs probably has its own noise and is unable to read the real RAM. This result was seen also before, while measuring the 56MHz RAM coupling with DARM.

(someone could argue that we don't know who is right and who is not, the proof is that ENV_RAM_56MHz show a coeherence with LSC_DARM while DAQ_EOM_56MHz_raw_mag does not)

Valid data are:

for the 8MHz August 22 at 11:55 UTC + 1200S
for the 56MHz August 22 at 12:50 UTC + 1500S

This stretch of data is AFTER the VGA gain setting to LowGain (August 22), while the test of the 56MHz coupling with DARM has been done in HighGain (July 31)

Attached: FFTs and Coherence of 8MHz and 56MHz

Images attached to this comment

paoletti - 15:56 Friday 23 August 2019 (46753)

Sorry for the mistake, the performed "VGA gain setting" action should have no effect on the interested channels named DAQ_EOM_xxMHz; conclusion of the entry are anyhow valid.