User talk:Steven J. Koch/Notebook/Kochlab/2009/07/29/Feedback tweaking, noise, FTC

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Andy Maloney 00:22, 30 July 2009 (EDT): Is the noise mechanical in origin? There may be ways of pin pointing where the noise is coming from if is is mechanical in nature. Also, do you think it could be coming from the QPD? I know there are some funky grounding issues associated with supplying power to it. I would like to help track down the noise issues so maybe I can get caught up with what is going on and help.

Steve Koch 01:13, 30 July 2009 (EDT): I think there's definitely substantial mechanical noise, and for sure at some point the acoustical noise in that room is going to come into play. We'll need to do systematic studies and I'd love if you helped Ant or Larry with those. Thanks! It's going to be tedious and frustrating--so, possibly if we can get some unzipping data before or during the improvements, it may make the need for reducing the noise more obvious. My guess is that the "noise" I'm seeing now is not coming from the QPD electronics, although that's possible. There are jumps in the sum signal, which I have been thinking are due to the power controller. But that could be a grounding issue. I'll see if I can post a picture of the data from today so we can get some bearings.