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EleonoraCapocasa - 11:41, Tuesday 14 July 2020 (2117)Get code to link to this report
Multiple Anti Aliasing channel failure

Yuhang, Eleonora

We report three additional failures of Anti Aliasing (AA) channels.

Symptom: ADC channel reads large, almost constant offset (order of ~1000 counts). The offeset is still present if we disconnect cables towards AA board -> it is not coming from the BNC2Dsub converter. The offset is reduced when we switched off AA board and disappear when we disconnect AA from ADC. 

This time the broken channels are:

- Ch.10 of AA0 used for INPUT YAW OPLEV (We realized it while charachterizing input oplev on 13/07)

- Ch.16 of AA0 used for END L SUM  OPLEV (not currently used, we know it is broken since several months)

- Ch.14 of AA1 board, used for  WFS2 Q3 (We realized it while charachterizing demodulators on 10/07)

For the moment I rearranged the model to used spare Anti Aliasing channels  for INPUT YAW OPLEV (chan 9-12 of AA0 moved to chan 25-28 of AA1).

We shoud understand the origin of such problem and solve it. According to Miyakawa-san It might be due to a ground-connection issue in the design of KAGRA Bnc2Dsub converter JGW-D1604781 https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=47