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.
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" 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A much shorter overview of LIGO, in Science Magazine, but from 1992 so a little out of date: http://www.ligo.caltech.edu/docs/P/P920010-00.pdf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)