org.mbari.siam.utils
Class StaLtaEventDetector

java.lang.Object
  org.mbari.siam.utils.StaLtaEventDetector

public class StaLtaEventDetector
extends java.lang.Object

Detect events based on ratio of moving short-term average ("STA") to moving long-term average ("LTA") of some input data. Detector is in "triggered" state when STA/LTA exceeds specified "trigger ratio". Detector is in "de-triggered" state when STA/LTA is less than specified "de-trigger" ratio. Notify listeners when state transitions between triggered and de-triggered states. Based on seismology algorithm described in "Instrumentation in Earthquake Seismology" by Havskov and Alguacil, p 117 (available at http://www.terraip.co.jp/Seismometers.pdf)

Nested Class Summary

static interface

StaLtaEventDetector.Listener Interface for event listeners

Field Summary

protected float	_deTriggerRatio
protected java.util.Vector	_listeners Event listeners
protected static org.apache.log4j.Logger	_log4j
protected double	_lta
protected java.util.LinkedList	_ltaSamples
protected int	_ltaSampleWidth
protected int	_maxTriggeredSamples Maximum consecutive sample accumulated in un-triggered state
protected int	_nConsecTriggeredSamples
protected long	_nSample
protected java.lang.String	_parameterName
protected boolean	_ready
protected double	_sta
protected java.util.LinkedList	_staSamples
protected int	_staSampleWidth
protected long	_transitionEpochMsec
protected boolean	_triggeredState
protected float	_triggerRatio

Constructor Summary

StaLtaEventDetector(java.lang.String parameterName, int staSampleWidth, int ltaSampleWidth, float triggerRatio, float deTriggerRatio, int maxTriggeredSamples)

Method Summary

void	addListener(StaLtaEventDetector.Listener listener) Add event listener
void	addSample(java.lang.Number newSample, long epochMsecTimestamp) Add next sample, compute moving averages and evaluate state
protected void	checkParameters(int staSampleWidth, int ltaSampleWidth, float triggerRatio, float deTriggerRatio, int maxTriggeredSamples) Check that user-set parameters are valid.
protected void	deTrigger(long epochMsec) Transition to detriggered state
double	getLTA()
long	getNsamples()
protected double	getRunningAverage(java.util.LinkedList samples, java.lang.Number newSample, int width, double prevAverage) Return running average
double	getSTA()
long	getTransitionTime() Return time of last transition, in epoch millsec
protected void	notifyListeners(boolean triggeredState) Notify listeners of state transition
void	reset() Reset; set averages to zero, restart accumulation
void	setParameters(int staSampleWidth, int ltaSampleWidth, float triggerRatio, float deTriggerRatio, int maxTriggeredSamples) Set parameters.
java.lang.String	toString() Return String representation
protected void	trigger(long epochMsec) Transition to triggered state
boolean	triggeredState() Return true if detector is in 'triggered' state, else return false.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

_log4j

protected static org.apache.log4j.Logger _log4j

_parameterName

protected java.lang.String _parameterName

_staSampleWidth

protected int _staSampleWidth

_ltaSampleWidth

protected int _ltaSampleWidth

_nSample

protected long _nSample

_maxTriggeredSamples

protected int _maxTriggeredSamples

Maximum consecutive sample accumulated in un-triggered state

_triggerRatio

protected float _triggerRatio

_deTriggerRatio

protected float _deTriggerRatio

_sta

protected double _sta

_lta

protected double _lta

_staSamples

protected java.util.LinkedList _staSamples

_ltaSamples

protected java.util.LinkedList _ltaSamples

_nConsecTriggeredSamples

protected int _nConsecTriggeredSamples

_triggeredState

protected boolean _triggeredState

_ready

protected boolean _ready

_transitionEpochMsec

protected long _transitionEpochMsec

_listeners

protected java.util.Vector _listeners

Event listeners

Constructor Detail

StaLtaEventDetector

public StaLtaEventDetector(java.lang.String parameterName,
                           int staSampleWidth,
                           int ltaSampleWidth,
                           float triggerRatio,
                           float deTriggerRatio,
                           int maxTriggeredSamples)
                    throws java.lang.Exception

Throws:

java.lang.Exception

Method Detail

toString

public java.lang.String toString()

Return String representation

Overrides:

toString in class java.lang.Object

getLTA

public double getLTA()

getSTA

public double getSTA()

getTransitionTime

public long getTransitionTime()

Return time of last transition, in epoch millsec

getNsamples

public long getNsamples()

reset

public void reset()

Reset; set averages to zero, restart accumulation

triggeredState

public boolean triggeredState()

Return true if detector is in 'triggered' state, else return false.

setParameters

public void setParameters(int staSampleWidth,
                          int ltaSampleWidth,
                          float triggerRatio,
                          float deTriggerRatio,
                          int maxTriggeredSamples)
                   throws java.lang.Exception

Set parameters. If input parameters are invalid, throws Exception without changing current parameters.

Throws:

java.lang.Exception

checkParameters

protected void checkParameters(int staSampleWidth,
                               int ltaSampleWidth,
                               float triggerRatio,
                               float deTriggerRatio,
                               int maxTriggeredSamples)
                        throws java.lang.Exception

Check that user-set parameters are valid.

Throws:

java.lang.Exception

getRunningAverage

protected double getRunningAverage(java.util.LinkedList samples,
                                   java.lang.Number newSample,
                                   int width,
                                   double prevAverage)

Return running average

addSample

public void addSample(java.lang.Number newSample,
                      long epochMsecTimestamp)
               throws java.lang.Exception

Add next sample, compute moving averages and evaluate state

Throws:

java.lang.Exception

trigger

protected void trigger(long epochMsec)

Transition to triggered state

deTrigger

protected void deTrigger(long epochMsec)

Transition to detriggered state

notifyListeners

protected void notifyListeners(boolean triggeredState)

Notify listeners of state transition

addListener

public void addListener(StaLtaEventDetector.Listener listener)

Add event listener