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Message ID: 6422     Entry time: Thu Mar 15 08:48:40 2012
Author: Ryan 
Type: Summary 
Category: CDS 
Subject: Summary of Syracuse Visit to 40m Mar 5-9 2012 

JIMS Channels in PEM Model

The PEM model has been modified now to include the JIMS(Joint Information Management System) channel processing. Additionally Jim added test points at the outputs of the BLRMS.

For each seismometer channel, five bands are compared to threshold values to produce boolean results.  Bands with RMS below threshold produce bits with value 1, above threshold results in 0.  These bits are combined to produce one output channel that contains all of the results.

A persistent version of the channel is generated by a new library block that called persist which holds the value at 0 for a number of time steps equal to an EPICS variable setting from the time the boolean first drops to zero. The persist allows excursions shorter than the timestep of a downsampled timeseries to be seen reliably.

The EPICS variables for the thresholds are of the form (in order of increasing frequency):
The EPICS variables for the persist step size are of the form:

The JIMS Channels are being recorded and written to frames:

The two JIMS channels at 2048:
[C1:PEM-JIMS_CH1_DQ] Persistent version of JIMS channel. When bit drops to zero indicating something bad (BLRMS threshold exceeded) happens the bit stays at zero  for >= the value of the persist EPICS variable.
[C1:PEM-JIMS_CH2_DQ] Non-persistent version of JIMS channel.

And all of the BLRMS channels at 256:
Names are of the form:

For additional details about the JIMS Channels and the implementation, please see the previous elog entries by Jim.



I have a working aLIGO Conlog/EPICS Log installed and running on megatron.

Please see this wiki page for the details of use:

I also edited this page with restart instructions for megatron:

Please see Ryan's previous elog entries for installation details.

Future Work

  • Determine useful thresholds for each band
  • Generate MEDM Screens for JIMS Channels
  • Add a decimation option to channels
  • Add EPICS Strings in PEM model to describe bits in JIMS Channels
  • Add additional JIMS Channels: Testing additional characterization methods
  • Implement a State Log on Megatron: Will Provide a 1Hz index into JIMS Channels
  • Generate a single web page that allows access to aLIGO Conlog/EPICS Log and State Log


ELOG V3.1.3-