1.  Program Name: 
       LockLoss

   2.  Authors:
       David Chin <dwchin@umich.edu>
       Keith Riles <kriles@umich.edu>
       University of Michigan

   3.  Purpose:
       Watch for acquisition and loss of lock. Based on thresholds
       in normalized transmitted light through the ends of the X 
       and Y arms.

   4.  Outputs:
                       
       A. Log and status web page
         
         Base directory: $GDSAPACHE/monitor_reports/LockLoss_XX
            browsable as http://server/gds/monitor_reports/LockLoss_XX
          
         where XX is one of {H1, H2, L1},
               server is one of blue.ligo-wa.caltech.edu
                                london.ligo-la.caltech.edu   
                              
         Let the base directory path or URL be assigned to BASEDIR.
         Log file:  $BASEDIR/LockLoss_Log.txt
         Status file: $BASEDIR/LockLoss_Uptime.html
         
       B. Graphical output
       
         i) Time series data (DMTviewer)

           LockLoss produces several time series of data of the 
           lock state of the interferometer.  The time series also
           includes different values based on the value of particular
           sets of bits in the State Vector.  These time series data
           are viewable using the DMTviewer.
         
           There are time series of different durations, the most useful
           (and most used) one being the 12 hour time series.
         
         
         ii) Lock segment histogram (DMTviewer)
         
           LockLoss also produces a histogram of lock stretches.  Again,
           these are viewable using DMTviewer.
         
         iii) Trends (Data Viewer)
         
           Minute trends of the same time series data are generated,
           as well.  Data Viewer is used to plot these in almost real time.
         
           Trend channel names are:
         
             XX:DMT-LOCKLOSS_XarmLOCK
             XX:DMT-LOCKLOSS_YarmLOCK
             XX:DMT-LOCKLOSS_BOTHarmsLOCK
             XX:DMT-LOCKLOSS_StateVEC

           The XarmLOCK, YarmLOCK, and BOTHarmsLOCK trends are
           self-descriptive.  The StateVEC trend is a trend of
           the StateVector data as displayed in the Control Room.
         
      C. Alarms
      
         LockLoss generates one alarm:
        
            Lock_lost
            
         (See http://server/gds/Alarms/)
            
      D. Meta-db triggers
         
         Triggers are generated in the meta-database.  The triggers are:
         
           Trigger type:  "Lock transition"
           Trigger subtypes:
           
             i)    X_arm_lock_acquired
             ii)   X_arm_lock_lost
             iii)  Y_arm_lock_acquired
             iv)   Y_arm_lock_lost
             v)    Both_arms_lock_acquired
             vi)   Both_arms_lock_lost

   5.  Usage Notes:
       Not meant to be run stand-alone by general users.

       
$Id: lockloss_desc.html,v 1.4 2003/09/15 00:51:07 dwchin Exp $