Since last tuesday, new demodulation mezzanines(SN34,SN42) are available in the Injection electronic lab in the DaqBox_SN26.
On wednesday, the cabling with demodulation mezzanine SN34 has been done by the Injection team :
- input0 with the EOM_6MHz monitoring
- input1 with the EOM_8MHz monitoring
- input2 with the EOM _22MHz monitoring
- input4 with the EOM_56MHz monitoring
A new server called EOM_Demod has been setup using the Acl development release on running on the rtpc6.
For each EOM input, the following monitoring channels are computed:
- DAQ_EOM_{freq}_raw_mag: the amplitude of the modulation line
- DAQ_EOM_{freq}_raw_phi: the phase on the line
- DAQ_EOM_{freq}_raw_dFreq{_NS,_100Hz): the frequency shift with the FPGS demodulation frequency
The first plot shows these channels for the EOM_22MHz input , and the last graph (bottom,right) shows the 400MHz sample FFT where one can see that on the EOM_22MHz monitoring the 56MHz line is well visible with an amplitude only lower by a factor 2.
The second plots shows the same things for the EOM_56MHz, the EOM_22MHz is visible too but its amplitude is 300 time lower
22MHz generator
The third plot shows the trend of the EOM_22MHz , it seems that the 22MHz generator is not phase locked on the GPS. To allow this a 100MHz clock is now available as the output on the demodulation mezzzanine SN34
Monitoring of the phase difference between the LNFS and EOM
As the LNSF modulation lines are monitored too , one can build the phase difference between LNSF and the EOM, this channel is available as DAQ_LNFS_EOM_{freq}_dPhi_100Hz.
The plots 4,5,6 shows the trend for the 6,8, and 56MHz.. For each demodulation frequency, the phase difference between the LNSF and the EOM change according the FmodErr tuning
the last plot shows the SSFS 56MHz phase with this 56MHz phase difference.
it could be interesting to propagate the EOM_56MHz_phase to the photodiode servers instead of the LNFS_56MHz_phase
