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MIF (General)
takafumi.ushiba - 14:32 Monday 02 June 2025 (34024) Print this report
Modification of the state requesting OBSERVATION to VIS guardians

Before the modification, OBSERVATION state to all VIS guardians are requested at ENGAGE_SUS_LINES state in LSC_LOCK guardian.
Since dewhitening filters for Type-C suspensions are engaged between LOCK_ACQUISITION state and OBSERVATION state, these dewhitening filters were not turned on at OBSERVATION_WITHOUT_LINES state, which is used for CAL measurement.
This is not good situration because calibration was done in the different configuration from the OBERVATION state, so I modified the guardian.

Modification was done for following two states.
Since final configuration is same as before, no change happened in OBSERVATION state.

ENGAGE_WHITENING_FILTERS:

Requests of OBSERVATION state to all VIS guardian, except for ETMX guardian, are done in this state.

ENGAGE_SUS_LINES:

Request of OBSERVATION state to only ETMX guardian is done in this state.

Comments to this report:
takahiro.yamamoto - 20:14 Friday 06 June 2025 (34098) Print this report
Though this update has no problem in lockloss-relock cycles, it makes non-uniqueness in each state with state transition between OBSERVATION and OBSERVATION_WITHOUT_LINES. Detailed state transition map is shown in Fig.1.

Requesting OBSERVATION to VIS guardians except ETMX was moved from ENGAGE_SUS_LINES to ENGAGE_WHITENING_FILTERS. But requesting LOW_NOISE to VIS guardians was still in DISENGAGE_SUS_LINES. For this reason, states of VIS guardians depend on the transition history of LSC_LOCK guardian. For removing this problem, we need to remove LOW_NOISE requests to VIS guardians except ETMX from DISENGAGE_SUS_LINES.

It probably occurrs only when we did the calibration measurements. So it's not so an urgent bug. But it's better to fix it until next calibration measurements in order to reduce human mistakes in the updates of calibration.

On today's calibration work (klog#34090), we requested OBSERVATION to VIS guardians manually for going back to OBSERVATION without guardian modification. A same issue should be occur in the morning calibration measurements (I haven't found a repot yet). It's better to check there is no wrong acceptance of SDF during the morning activities or not.
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