We have been called by the operator for two unlocks for which the PSTAB was suspected. From the analysis we made, PSTAB is not responsible:

# 16H05MN33S_UTC, see plot 1

we see HF_CORR drifting up to the point where it saturates. Before the saturation the PSTAB makes the job and the error signal is kept to zero as expected. We clearly see that at 33,3 sec the IMC faces some issue wrt its alignment. This induces some more demand to the PSTAB which gave up at some point.

The alignement issue is connected to an unexpected opening of the BPC loop (Probelm with the card?)

# 16H14MN00S_UTC, see plot 2 and 3 (zoom)

SSFS_CORR oscillates at 10 kHz for some reason that we do not explain. This oscillation is also visible also on the IMC_REF error signals. This shake the IMC and induces a 2f counterpart on the IMC transmission. At the end PSTAB tries to manage this extra noise, but seems to be not part of the culprits.

# from 16H43MN20SEC to 16H43MN37SEC UTC, (roughly), we switched OFF and ON the PSTAB to check whether it could unlock the ITF. It did not.