for some reason the DAC noise estimate is too high, it can't really be so large compared to the real DARM curve (see the noise budget curves from LLO - there are other noise sources besides DAC noise)

some possibilities:

1. maybe the DAC noise calibration into meters is wrong? I can't tell from the code where this came from. It would be good to put a comment in there.
2. perhaps most of this noise is actually angular noise. The ASC control signals are adjusted by tuning the digital coefficients (before MASTER_OUT) so that the angle to length coupling is minimized. I think something like this has to be done to remove the angular noise from the DAC noise estimate.
3. internal saturation of the DAC noise monitor?

I hve modified the code to plot nicer and also to remove some divide by zero problems. There is also still some warnings about other divide by zero - those should probably be fixed by examining how better to handle it when the coherence goes to zero.