To tune the demodulation phase of any R signal, you have to inject a line and typically minimize the line in the Q spectrum and maximize in the I spectrum.

The attached script help in this operation. If you set up the I and Q channel names and the frequency of the line you are injecting, it shows a StripTool like chart showing in real time the ratio of Q over I at the line frequency. You can then move the demodulation phase to bring the ratio to zero. Since what is plotted is the transfer function, it has a sign, so you can rely on the zero crossing.

This script can be easily modified to carry out different tasks, for example

• tuning the longitudinal offset of a cavity (using the transmited power)
• tuning the angular offsets of the IMC, injecting a jitter line and changing the ASC offsets
• ....