KAGRA Logbook

Reports 1-1 of 1

MIF (ITF Control)

masayuki.nakano - 18:00 Monday 27 January 2020 (12661)

RF45 demod phase

[Aso, Nakano]

We checked the demod phase of the RF45 analog signal, and supprisingly it was almost 90 deg rotated. So, we controled the CARM DoF by RF45Q, and it might cause the unstability of the PRFPMI. I did not close the CARM loop with the current demod phase, due to the earthquake, and the k1lsc0 trouble. I will try it tomorrow.

Comments to this report:

takahiro.yamamoto - 11:24 Tuesday 28 January 2020 (12668)

I discussed the mystery of current setting of demod. phase with Nakano-kun.

We may need some modifications on analog part
because DAC output range is not enough for changing from 0deg. to 360deg.

- Current setting of demod. phase is 8.362 Volts (see fig1)
- We can set demod. phase as between 0V and 5V (see fig2)
- We can do as between -5V and 5V by removing saturation block from k1alspll.
- We need to set as between 0V to 12V for changing from 0deg. to 360deg.

Images attached to this comment

yutaro.enomoto - 13:37 Tuesday 28 January 2020 (12671)

Hi all,

My original thought was the following:
- as the DAC output is finally output by a Dsub-BNC converter, it will be useful if the output range (seen in MEDM) is from -5 to +5 V.
- as the analog phase shifter only receives positive voltage, it is safer to set limits.
- though it is not very useful, I thought it is fine if we can shift the phase by 90 deg. at max.