Added kalman filter to reduce noice in geo locations

src/main/java/com/kalmanFilters/Tracker1D.java

@@ -0,0 +1,158 @@
+package com.kalmanFilters;
+
+
+/**
+ * Kalman filter tracking in one dimension.
+ */
+class Tracker1D {
+
+    // Settings
+
+    /**
+     * Time step
+     */
+    private final double mt, mt2, mt2d2, mt3d2, mt4d4;
+
+    /**
+     * Process noise covariance
+     */
+    private final double mQa, mQb, mQc, mQd;
+
+    /**
+     * Estimated state
+     */
+    private double mXa, mXb;
+
+    /**
+     * Estimated covariance
+     */
+    private double mPa, mPb, mPc, mPd;
+
+    /**
+     * Creates a tracker.
+     *
+     * @param timeStep Delta time between predictions. Usefull to calculate speed.
+     * @param processNoise Standard deviation to calculate noise covariance from.
+     */
+    public Tracker1D(double timeStep, double processNoise) {
+
+        // Lookup time step
+        mt = timeStep;
+        mt2 = mt * mt;
+        mt2d2 = mt2 / 2.0;
+        mt3d2 = mt2 * mt / 2.0;
+        mt4d4 = mt2 * mt2 / 4.0;
+
+        // Process noise covariance
+        double n2 = processNoise * processNoise;
+        mQa = n2 * mt4d4;
+        mQb = n2 * mt3d2;
+        mQc = mQb;
+        mQd = n2 * mt2;
+
+        // Estimated covariance
+        mPa = mQa;
+        mPb = mQb;
+        mPc = mQc;
+        mPd = mQd;
+    }
+
+    /**
+     * Reset the filter to the given state.
+     * <p>
+     * Should be called after creation, unless position and velocity are assumed to be both zero.
+     *
+     * @param position
+     * @param velocity
+     * @param noise
+     */
+    public void setState(double position, double velocity, double noise) {
+
+        // State vector
+        mXa = position;
+        mXb = velocity;
+
+        // Covariance
+        double n2 = noise * noise;
+        mPa = n2 * mt4d4;
+        mPb = n2 * mt3d2;
+        mPc = mPb;
+        mPd = n2 * mt2;
+    }
+
+    /**
+     * Update (correct) with the given measurement.
+     *
+     * @param position
+     * @param noise
+     */
+    public void update(double position, double noise) {
+
+        double r = noise * noise;
+
+        //  y   =  z   -   H  . x
+        double y = position - mXa;
+
+        // S = H.P.H' + R
+        double s = mPa + r;
+        double si = 1.0 / s;
+
+        // K = P.H'.S^(-1)
+        double Ka = mPa * si;
+        double Kb = mPc * si;
+
+        // x = x + K.y
+        mXa = mXa + Ka * y;
+        mXb = mXb + Kb * y;
+
+        // P = P - K.(H.P)
+        double Pa = mPa - Ka * mPa;
+        double Pb = mPb - Ka * mPb;
+        double Pc = mPc - Kb * mPa;
+        double Pd = mPd - Kb * mPb;
+
+        mPa = Pa;
+        mPb = Pb;
+        mPc = Pc;
+        mPd = Pd;
+    }
+
+    /**
+     * Predict state.
+     *
+     * @param acceleration Should be 0 unless there's some sort of control input (a gas pedal, for instance).
+     */
+    public void predict(double acceleration) {
+
+        // x = F.x + G.u
+        mXa = mXa + mXb * mt + acceleration * mt2d2;
+        mXb = mXb + acceleration * mt;
+
+        // P = F.P.F' + Q
+        double Pdt = mPd * mt;
+        double FPFtb = mPb + Pdt;
+        double FPFta = mPa + mt * (mPc + FPFtb);
+        double FPFtc = mPc + Pdt;
+        double FPFtd = mPd;
+
+        mPa = FPFta + mQa;
+        mPb = FPFtb + mQb;
+        mPc = FPFtc + mQc;
+        mPd = FPFtd + mQd;
+    }
+
+    /**
+     * @return Estimated position.
+     */
+    public double getPosition() { return mXa; }
+
+    /**
+     * @return Estimated velocity.
+     */
+    public double getVelocity() { return mXb; }
+
+    /**
+     * @return Accuracy
+     */
+    public double getAccuracy() { return Math.sqrt(mPd / mt2); }
+}

src/main/java/com/marianhello/bgloc/Config.java

@@ -63,6 +63,7 @@ public class Config implements Parcelable
     private HashMap httpHeaders;
     private Integer maxLocations;
     private LocationTemplate template;
+    private Boolean applyKalmanFilter;
 
     public Config () {
     }
@@ -95,6 +96,7 @@ public Config(Config config) {
         if (config.template instanceof AbstractLocationTemplate) {
             this.template = ((AbstractLocationTemplate)config.template).clone();
         }
+        this.applyKalmanFilter = config.applyKalmanFilter;
     }
 
     private Config(Parcel in) {
@@ -123,6 +125,7 @@ private Config(Parcel in) {
         Bundle bundle = in.readBundle();
         setHttpHeaders((HashMap<String, String>) bundle.getSerializable("httpHeaders"));
         setTemplate((LocationTemplate) bundle.getSerializable(AbstractLocationTemplate.BUNDLE_KEY));
+        setApplyKalmanFilter((Boolean) in.readValue(null));
     }
 
     public static Config getDefault() {
@@ -151,6 +154,7 @@ public static Config getDefault() {
         config.httpHeaders = null;
         config.maxLocations = 10000;
         config.template = null;
+        config.applyKalmanFilter = true;
 
         return config;
     }
@@ -183,6 +187,7 @@ public void writeToParcel(Parcel out, int flags) {
         out.writeString(getSyncUrl());
         out.writeInt(getSyncThreshold());
         out.writeInt(getMaxLocations());
+        out.writeValue(getApplyKalmanFilter());
         Bundle bundle = new Bundle();
         bundle.putSerializable("httpHeaders", getHttpHeaders());
         bundle.putSerializable(AbstractLocationTemplate.BUNDLE_KEY, (AbstractLocationTemplate) getTemplate());
@@ -520,6 +525,15 @@ public void setTemplate(LocationTemplate template) {
         this.template = template;
     }
 
+    public boolean hasApplyKalmanFilter() {
+        return applyKalmanFilter != null;
+    }
+
+    public void setApplyKalmanFilter(Boolean applyKalmanFilter) { this.applyKalmanFilter = applyKalmanFilter; }
+
+    public Boolean getApplyKalmanFilter() { return applyKalmanFilter; }
+
+
     @Override
     public String toString () {
         return new StringBuffer()
@@ -547,6 +561,7 @@ public String toString () {
                 .append(" httpHeaders=").append(getHttpHeaders().toString())
                 .append(" maxLocations=").append(getMaxLocations())
                 .append(" postTemplate=").append(hasTemplate() ? getTemplate().toString() : null)
+                .append(" applyKalmanFilter=").append(getApplyKalmanFilter())
                 .append("]")
                 .toString();
     }
@@ -639,6 +654,9 @@ public static Config merge(Config config1, Config config2) {
         if (config2.hasTemplate()) {
             merger.setTemplate(config2.getTemplate());
         }
+        if (config2.hasApplyKalmanFilter()) {
+            merger.setApplyKalmanFilter(config2.getApplyKalmanFilter());
+        }
 
         return merger;
     }

src/main/java/com/marianhello/bgloc/data/sqlite/SQLiteConfigurationContract.java

@@ -40,6 +40,7 @@ public static abstract class ConfigurationEntry implements BaseColumns {
         public static final String COLUMN_NAME_HEADERS = "http_headers";
         public static final String COLUMN_NAME_MAX_LOCATIONS = "max_locations";
         public static final String COLUMN_NAME_TEMPLATE = "template";
+        public static final String COLUMN_NAME_APPLY_KALMAN_FILTER = "applyKalmanFilter";
 
         public static final String SQL_CREATE_CONFIG_TABLE =
                 "CREATE TABLE " + ConfigurationEntry.TABLE_NAME + " (" +
@@ -67,7 +68,8 @@ public static abstract class ConfigurationEntry implements BaseColumns {
                         ConfigurationEntry.COLUMN_NAME_SYNC_THRESHOLD + INTEGER_TYPE + COMMA_SEP +
                         ConfigurationEntry.COLUMN_NAME_HEADERS + TEXT_TYPE + COMMA_SEP +
                         ConfigurationEntry.COLUMN_NAME_MAX_LOCATIONS + INTEGER_TYPE + COMMA_SEP +
-                        ConfigurationEntry.COLUMN_NAME_TEMPLATE + TEXT_TYPE +
+                        ConfigurationEntry.COLUMN_NAME_TEMPLATE + TEXT_TYPE + COMMA_SEP +
+                        ConfigurationEntry.COLUMN_NAME_APPLY_KALMAN_FILTER + INTEGER_TYPE +
                         " )";
 
         public static final String SQL_DROP_CONFIG_TABLE =

src/main/java/com/marianhello/bgloc/data/sqlite/SQLiteConfigurationDAO.java

@@ -56,7 +56,8 @@ public Config retrieveConfiguration() throws JSONException {
       ConfigurationEntry.COLUMN_NAME_SYNC_THRESHOLD,
       ConfigurationEntry.COLUMN_NAME_HEADERS,
       ConfigurationEntry.COLUMN_NAME_MAX_LOCATIONS,
-      ConfigurationEntry.COLUMN_NAME_TEMPLATE
+      ConfigurationEntry.COLUMN_NAME_TEMPLATE,
+      ConfigurationEntry.COLUMN_NAME_APPLY_KALMAN_FILTER
     };
 
     String whereClause = null;
@@ -123,7 +124,7 @@ private Config hydrate(Cursor c) throws JSONException {
     config.setHttpHeaders(new JSONObject(c.getString(c.getColumnIndex(ConfigurationEntry.COLUMN_NAME_HEADERS))));
     config.setMaxLocations(c.getInt(c.getColumnIndex(ConfigurationEntry.COLUMN_NAME_MAX_LOCATIONS)));
     config.setTemplate(LocationTemplateFactory.fromJSONString(c.getString(c.getColumnIndex(ConfigurationEntry.COLUMN_NAME_TEMPLATE))));
-
+    config.setApplyKalmanFilter( (c.getInt(c.getColumnIndex(ConfigurationEntry.COLUMN_NAME_APPLY_KALMAN_FILTER)) == 1) ? true : false );
     return config;
   }
 
@@ -154,6 +155,7 @@ private ContentValues getContentValues(Config config) throws NullPointerExceptio
     values.put(ConfigurationEntry.COLUMN_NAME_HEADERS, new JSONObject(config.getHttpHeaders()).toString());
     values.put(ConfigurationEntry.COLUMN_NAME_MAX_LOCATIONS, config.getMaxLocations());
     values.put(ConfigurationEntry.COLUMN_NAME_TEMPLATE, config.hasTemplate() ? config.getTemplate().toString() : null);
+    values.put(ConfigurationEntry.COLUMN_NAME_APPLY_KALMAN_FILTER, (config.getApplyKalmanFilter() == true) ? 1 : 0);
 
     return values;
   }

src/main/java/com/marianhello/bgloc/data/sqlite/SQLiteOpenHelper.java

@@ -82,7 +82,7 @@ public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
                 alterSql.add(SQL_CREATE_CONFIG_TABLE);
             case 11:
                 alterSql.add("ALTER TABLE " + LocationEntry.TABLE_NAME +
-                        " ADD COLUMN " + LocationEntry.COLUMN_NAME_RADIUS + REAL_TYPE);
+                        " ADD COLUMN " + LocationEntry.COLUMN_NAME_STOP_TERMINATE + REAL_TYPE);
                 alterSql.add("ALTER TABLE " + LocationEntry.TABLE_NAME +
                         " ADD COLUMN " + LocationEntry.COLUMN_NAME_HAS_ACCURACY + INTEGER_TYPE);
                 alterSql.add("ALTER TABLE " + LocationEntry.TABLE_NAME +
@@ -140,4 +140,4 @@ public void execAndLogSql(SQLiteDatabase db, String sql) {
             Log.e(TAG, "Error executing sql: " + e.getMessage());
         }
     }
-}
+}