I'd like to re-measure the transfer function from driving MC2 position to the MC_L_DQ channel (for feedforward purposes). Swept sine would be one option, but I can't get the "Envelope" feature of DTT to work, the excitation amplitude isn't getting scaled as specified in the envelope, and so I'm unable to make the measurement near 1 Hz (which is where the FF is effective). I see some scattered mentions of such an issue in past elogs but no mention of a fix (I also feel like I have gotten the envelope function to work for some other loop measurement templates). So then I thought I'd try broadband noise injection, since that seems to have been the approach followed in the past. Again, the noise injection needs to be shaped around ~1 Hz to avoid knocking the IMC out of lock, but I can't get Foton to do shaped noise injections because it doesn't inherit the sample rate when launched from inside DTT/awggui - this is not a new issue, does anyone know the fix?
Note that we are using the gds2.15 install of foton, but the pre-packaged foton that comes with the SL7 installation doesn't work either.
The envelope feature for swept-sine wasn't working because i specified the frequency grid in the wrong order apparently. Eric von Reis has been notified to include a sorting algorithm in future DTT so that this can be in arbitrary order. fixing that allows me to run a swept sine with enveloped excitation amplitude and hence get the TF I want, but still no shaped noise injections via foton 😢