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absGlitch: An Absolute Threshold- based Glitch Monitor
R. Rahkola, R. Schofield LSC Meeting, March 20- 23, 2002

LIGO - G020047 - 00- Z absGlitch Monitor


Why "absGlitch"?
It's based on Masahiro Ito's glitchMon monitor. However, rather than using `3 s` thresholds, we give thresholds in units of ADC counts. This makes absGlitch more sensitive to gradual changes in noise. absGlitch produces and serves histograms of glitch amplitudes:
ь For a single "Log Interval" ь For the entire duration of the monitor

absGlitch can be used by the Burst group to veto events.

LIGO - G020047 - 00- Z absGlitch Monitor

LSC Meeting, March 20-23, 2002

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How do you set thresholds?
q absGlitch has a variety of output: ь Log file output ь Data file output (triggers) ь Trigger manager output q You can use the log file output to re-write your

configuration file. q Successful iterations of absGlitch on offline data provides all the info you need to set reasonable thresholds.

LIGO - G020047 - 00- Z absGlitch Monitor

LSC Meeting, March 20-23, 2002

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Input and Output
Configuration File:
ь "Header" section sets global parameters ь "Channel" section sets parameters for individual channels
o Threshold level o Whether the Operating State Condition needs to be satisfied first o Filter parameters

Data File:
ь Labels for all fields are at the beginning of each file ь Event timestamps are given both in GPS and UTC ь Precisely overlaps GDS_trigger metadata information

Log File:
ь "Header" section repeats the configuration file... ("Now what configuration file did I
use to produce this output?")

ь Prints the histogram data available for each channel every Log_I nterval seconds (i.e.
number of triggers at each amplitude level, dead time due to eac h level, etc.)
LSC Meeting, March 20-23, 2002

LIGO - G020047 - 00- Z absGlitch Monitor

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More Info Please...
Check out: http://www. ligo-wa.caltech.edu/~rrahkola/absGlitch/, or the
documents associated with your local distribution of GDS (post-LSC mtg)

LIGO - G020047 - 00- Z absGlitch Monitor

LSC Meeting, March 20-23, 2002

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