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Alarm Intensity Filtering Processor

IP.com Disclosure Number: IPCOM000106808D
Original Publication Date: 1993-Dec-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 4 page(s) / 79K

Publishing Venue

IBM

Related People

Abel, M: AUTHOR [+3]

Abstract

An efficient method for limiting alarm information shared between systems is disclosed. The intensity or frequency of alarm arrivals is used as a filter to minimize the amount of data transmitted. Approximation of alarm arrival rates is used to minimize the system resources required for processing.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 53% of the total text.

Alarm Intensity Filtering Processor

      An efficient method for limiting alarm information shared
between systems is disclosed.  The intensity or frequency of alarm
arrivals is used as a filter to minimize the amount of data
transmitted.  Approximation of alarm arrival rates is used to
minimize the system resources required for processing.

Let

o   w = filter window size (seconds)

o   n = filter window threshold (events)

o   d = decay constant

o   r = trigger threshold

o   f = filter level

o   i = time (in seconds) between equidistant events

o   m = decay factor for equidistant events

o   r = single event decay requirement

      The user input parameters for the filter are w and n. If the
intensity filter is set to trigger after 15 events received over 60
seconds, then w (the filter window size) is 60 (seconds), and n (the
number of events to trigger this filter) is 15.

The other variables are calculated from w and n.

      The novelty of this approach and the resultant conservation of
system resources is the result of the fact that the intensity filter
does not measure the number of events received over the past w
seconds precisely.  The filter is instead an approximation that
conserves memory.  It may take more or less than n events to trigger
the filter.  The interpretation of the user's specification of w and
n is as follows:

      "If no events have been received previously, and a stream of
equally spaced alarms arrives over a time period filling precisely w
seconds, the filter is 'just barely' triggered."

      "Just barely" means that if the counters were cleared and the
the series of alarms repeated, moving any alarm farther from the
first alarm in the series would cause the filter to not be triggered.

      Consider an alarm that is "just barely" triggered with equally
spaced events.  Determine the time between each event,

   i = w / (n-1)
represented in seconds.  Define f as the present filter "level";
i.e., the approximate number of events presently in the intensity
filter.  Every time a new alarm comes in for this intensity filter,

   f = f * exp(d * elapsed_time) + 1

      Here elapsed_time represents the number of seconds that have
passed since the last event arrived in this filter.  For now, d is a
negative floating point number representing a decay constant derived
from w and n. A method for determining the best choice for d is
described later.

      For the st...