feat: added the Noise Detection enhancement to the Auto-Scale feature

Author: AsCress

app/src/main/java/io/pslab/activity/OscilloscopeActivity.java

@@ -26,6 +26,7 @@
 import android.widget.LinearLayout;
 import android.widget.RelativeLayout;
 import android.widget.TextView;
+import android.widget.Toast;
 
 import androidx.annotation.IdRes;
 import androidx.annotation.NonNull;
@@ -1170,7 +1171,7 @@ protected void onPostExecute(Void aVoid) {
     public void autoScale() {
         double minY = Double.MAX_VALUE;
         double maxY = Double.MIN_VALUE;
-        double maxPeriod = Double.MIN_VALUE;
+        double maxPeriod = -1 * Double.MIN_VALUE;
         double yRange;
         double yPadding;
         double[] voltage = new double[512];
@@ -1203,14 +1204,14 @@ public void autoScale() {
         }
         yRange = maxY - minY;
         yPadding = yRange * 0.1;
-        if ((maxPeriod * 5) < maxTimebase) {
-            xAxisScale = maxPeriod * 5;
+        if (maxPeriod > 0) {
+            xAxisScale = Math.min((maxPeriod * 5), maxTimebase);
+            yAxisScale = maxY + yPadding;
+            samples = 512;
+            timeGap = (2 * xAxisScale * 1000.0) / samples;
         } else {
-            xAxisScale = maxTimebase;
+            Toast.makeText(this, getString(R.string.auto_scale_error), Toast.LENGTH_SHORT).show();
         }
-        yAxisScale = maxY + yPadding;
-        samples = 512;
-        timeGap = (2 * xAxisScale * 1000.0) / samples;
     }
 
     public class XYPlotTask extends AsyncTask<String, Void, Void> {

app/src/main/java/io/pslab/communication/AnalyticsClass.java

@@ -10,6 +10,7 @@
 import org.apache.commons.math3.transform.DftNormalization;
 import org.apache.commons.math3.transform.FastFourierTransformer;
 import org.apache.commons.math3.transform.TransformType;
+
 import io.pslab.filters.BandstopFilter;
 import io.pslab.filters.Lfilter;
 
@@ -330,7 +331,12 @@ public double findFrequency(double[] voltage, double samplingInterval) {
                 index = i;
             }
         }
-        return frequency[index];
+        double noiseThreshold = 0.1;
+        if (max >= noiseThreshold) {
+            return frequency[index];
+        } else {
+            return -1;
+        }
     }
 
     public ArrayList<double[]> amplitudeSpectrum(double[] voltage, int samplingInterval, int nHarmonics) {

app/src/main/res/values/strings.xml

@@ -1056,6 +1056,7 @@
     <string name="limit_average">Average</string>
     <string name="no_playback_data">No data to display</string>
     <string name="privacy_policy">Privacy Policy</string>
+    <string name="auto_scale_error">No input found</string>
     <string name="auto_scale">Auto</string>
     <string name="control_stop">Stop</string>
     <string name="control_run">Run</string>