SEI System Real-Time Band-Limited RMS Filter (ISI Performance Matrix, Matrices)

Document #:

LIGO-T1100613-v3

Document type:

T - Technical notes

Abstract:

We describe the implementation of a digital real-time band-limited RMS monitor (BLRMS). The necessary C code, matlab scripts, simulink parts, and medm screens are also documented. We characterize the accuracy of the monitor by feeding in a uniform power signal in a particular frequency band and measuring the output of the filter to compare to the real value. We also provide instructions to normalize the output of the filter to the Advanced LIGO requirement for a particular instrument.
Note: This is based on filters developed by Daw et. al. described in P040015

Files in Document:

• blrms.pdf (375.7 kB)

Other Files:

• blrms_all.zip (471.0 kB)
• contains the time constants for the filters (sos_coefs_output.txt, 6.2 kB)

Topics:

• Data and Computing
• Data Analysis

Authors:

• Christopher Kucharczyk
• Brian Lantz

Keywords:

band-limited rms monitor blrms filter

Notes and Changes:

updated the document for the an updated version of BLRMSFILTER.c

Related Documents:

• LIGO-P040015: Long Term Study of the Seismic Environment at LIGO

Referenced by:

• LIGO-E1200686-v2: aLIGO HAM-ISI, "Common Documentation" (List of all DCC trees, wikis, and general documentation)
• LIGO-E1300815: SEI Controls Document Hub
• LIGO-T2200025-v2: Update to the BLRMS Code: Custom BLRMS, Transposed Direct Form 2, and Reduced DC Order