org.android.activityminer.logic.filter
Class GravitationFilter

java.lang.Object
  org.android.activityminer.logic.filter.GravitationFilter

public class GravitationFilter
extends Object

Adaption of the original android 2.3.7 gravity filter reference implementation from API-Level 10 source. (Quelle: https://github.com/android/platform_frameworks_base/blob/gingerbread-release/services/sensorservice/GravitySensor.cpp).

Field Summary

private ButterworthLowPassFilter.BWFilter	bwFilter The filter for coefficient calculation
private ButterworthLowPassFilter.CascadedBiquadIIRBWFilter[]	cbqFilter The filters for gravitation component in the three axis values.
static double	DEFAULT_CORNER_FREQUENCY The default corner frequency for the butterworth filter
(package private) long	lastDt The last time differences

Constructor Summary

GravitationFilter(double fc)
Constructor

GravitationFilter(double fc, int order)
Constructor

Method Summary

double[]	filter(double[] currentSample, double[] a, long dt) The filter method.
double[]	init(double[] currentSample, double[] a) Initialization with the previous x value.
double[]	init(double[] currentSample, double[] a, long dt) Initialization with the previous x value.
static boolean	validateCutOffFreq(double fc, long samplerate) Cut-Off frequency validation.

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_CORNER_FREQUENCY

public static final double DEFAULT_CORNER_FREQUENCY

The default corner frequency for the butterworth filter

See Also:

Constant Field Values

cbqFilter

private final ButterworthLowPassFilter.CascadedBiquadIIRBWFilter[] cbqFilter

The filters for gravitation component in the three axis values.

bwFilter

private final ButterworthLowPassFilter.BWFilter bwFilter

The filter for coefficient calculation

lastDt

long lastDt

The last time differences

Constructor Detail

GravitationFilter

public GravitationFilter(double fc)

Constructor

Parameters:

fc - the corner frequency

GravitationFilter

public GravitationFilter(double fc,
                         int order)

Constructor

Parameters:

fc - the corner frequency

order - the filter order

Method Detail

init

public final double[] init(double[] currentSample,
                           double[] a)

Initialization with the previous x value.

Parameters:

currentSample - the current sample to store values in

a - the current raw acceleration values

Returns:

the current sample

init

public final double[] init(double[] currentSample,
                           double[] a,
                           long dt)

Initialization with the previous x value.

Parameters:

currentSample - the current sample to store values in

a - the current raw acceleration values

dt - the current time delta between samples in milliseconds

Returns:

the current sample

filter

public double[] filter(double[] currentSample,
                       double[] a,
                       long dt)

The filter method.

Parameters:

currentSample - the current sample to store values in

a - the current raw acceleration values

dt - the current time delta between samples in milliseconds

Returns:

the current sample

validateCutOffFreq

public static boolean validateCutOffFreq(double fc,
                                         long samplerate)

Cut-Off frequency validation.

Parameters:

fc - the cut-off frequency

samplerate - the current maximum sample rate

Returns:

true if valid, false otherwise