We added the following two new DAQ channels into the c1:GCV model. The daq:analog input channels are on card ADC0 and correspond to channels 3 and 4 on the card.
c1:GCV-EXT_REF_OUT_DAQ Sampling rate=2kHz acquiring a 1Hz sine wave from the SRS Function Generator DS345. This is using the Rb 10MHz signal as an external frequency reference.
c1:GCV-PLL_OUT_DAQ Sa.rate=2kHz acquiring the demodulated signal from the PLL servo.
This work is connected to the study of VCO PLL loop noise at frequencies below 0.1Hz. We are trying to measure phase noise in the VCO PLL servo at low frequencies as this noise would result in arm length fluctuations in the green-locking scheme.