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<== Date ==> <== Thread ==>

Subject: Re: AlarmHandler - filtering vs. HYST
From: Steve Lewis <SALewis@llnl.gov>
To: "Brian McAllister" <mcallister@mit.edu>
Cc: Terry Carlino <carlino@jlab.org>, tech-talk@aps.anl.gov
Date: Fri, 14 Apr 2006 12:44:56 -0700
At 3:03 PM -0400 2006/04/14, Brian McAllister wrote:

> Steve Lewis wrote: >> Try this (one of the best features of ALH): use >> $ALARMCOUNTFILTER count seconds

This will help you, but (IMO) the best solution for any alarm hovering
around a transition value is almost always to set HYST appropriately in the
record.

...snip...


I did not mean to imply HYST=0. In fact, I always set it appropriately for electronic noise and digitization artifacts. The filter is most useful for occasional, random excursions. And, yes, NOACKT is usually the right choice for these types of signals.





Based on personal experience I can state that any significant number of
"nuisance" alarms will lead to users becoming less reactive to real alarms.

We were having enough issues with operators silencing ALH "forever" (so
they wouldn't be annoyed by "false" alarms) that I modified ALH to put a
black border around the button on the screen so you could tell it was
silenced without opening the alarm window.


Agreed: sufficient false positives will always result in defeat of the system. I like your visual fix as well.
References:
Re: AlarmHandler - filtering vs. HYST Brian McAllister

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