== Active Noise Cancellation ==

Active noise cancellation in this context is the process of independently measuring a noise source (seismic or acoustic noise), and then subtracting that noise from the LIGO control channels.  

[[attachment:ProjectProposal.pdf]]

[[attachment:JulyProgressReport.pdf]]

[[attachment:AugustProgressReport.pdf]]

=== Reading: ===

 * Poster Presented on Active Noise Cancellation at March 2009 LVC meeting:  WienerFilteringPoster

 * A fairly easy to read paper overviewing how LIGO works:  "LIGO: The Laser Interferometer Gravitational Wave Observatory" [[attachment:P070082-v2.pdf]]
 * A much shorter overview of LIGO, in Science Magazine, but from 1992 so a little out of date: http://www.ligo.caltech.edu/docs/P/P920010-00.pdf

Both of the following two books are good references on the basics of Wiener Filtering and Adaptive Filtering:

 * Haykin, S.  "Adaptive Filter Theory" 2002  (chapters on Wiener Filtering, and LMS Algorithm for Adaptive Filtering)

 * Farhang-Boroujeny, B. "Adaptive Filters: Theory and Applications" 1998 (chapters on Wiener Filtering, and LMS Algorithm for Adaptive Filtering)

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=== Previous SURFs on this topic ===
[[Adaptive_Filter]]

[[Gravity_Gradients]]