The CARM common mode servo gain configuration was not optimized and it has 10 times more servo noise. That limited the sensitivity and the binary range was improved up to 390 kpc.
- Before the input gain was -20 dB (20 dB attenuator between the CMS and the IQ demod) and the output gain was 30 dB. This means we had 10 times larger servo noise. So, I increased input gain to 0 dB (removing attenuator) and reduce the output gain to 10 dB.
- I put two HPF reported by Akutsu san in klog12959. However, I asked Yamat-sensei to remove one of them due to the phase delay.
- Still, we have unknown low frequency noise at I/Q demod board. We will continue to investigate it.
- The lock stability is amazingly good even without ASC. It is an advantage of underground, I guess.