diff --git a/app/build.gradle b/app/build.gradle
index 02a2cc2..2de059c 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -51,4 +51,7 @@ dependencies {
implementation "androidx.camera:camera-video:${camerax_version}"
implementation "androidx.camera:camera-view:${camerax_version}"
implementation "androidx.camera:camera-extensions:${camerax_version}"
+
+
+ implementation 'com.jjoe64:graphview:4.2.2'
}
\ No newline at end of file
diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index 3ea0c3b..f940acb 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -6,6 +6,11 @@
+
+
+
+
+
{
+ private AudioRecord recorder;
+ private final int sampleRateInHz = 44100;
+ private final int channelConfig = AudioFormat.CHANNEL_IN_MONO;
+ private final int audioFormat = AudioFormat.ENCODING_PCM_16BIT;
+ private int minPufferGroesseInBytes;
+ private int pufferGroesseInBytes;
+ private RingPuffer ringPuffer = new RingPuffer(10);
+ private float kalibierWert;
+ private DetectionReport detectionReport;
+
+ AufnahmeTask() {
+ minPufferGroesseInBytes = AudioRecord.getMinBufferSize(sampleRateInHz, channelConfig, audioFormat);
+ pufferGroesseInBytes = minPufferGroesseInBytes * 2;
+ if (ActivityCompat.checkSelfPermission(MainActivityForClass, Manifest.permission.RECORD_AUDIO) != PackageManager.PERMISSION_GRANTED) {
+ // TODO: Consider calling
+ // ActivityCompat#requestPermissions
+ // here to request the missing permissions, and then overriding
+ // public void onRequestPermissionsResult(int requestCode, String[] permissions,
+ // int[] grantResults)
+ // to handle the case where the user grants the permission. See the documentation
+ // for ActivityCompat#requestPermissions for more details.
+ ActivityCompat.requestPermissions(MainActivityForClass, new String[]{Manifest.permission.RECORD_AUDIO}, RECHTEANFORDERUNG_MIKROFON);
+ }
+
+ recorder = new AudioRecord(MediaRecorder.AudioSource.MIC, sampleRateInHz, channelConfig, audioFormat, pufferGroesseInBytes);
+
+// textViewMinPufferGroesseInBytes.setText("" + minPufferGroesseInBytes);
+// textViewPufferGroesseInBytes.setText("" + pufferGroesseInBytes);
+// textViewAbtastrate.setText("" + recorder.getSampleRate());
+// textViewAnzahlKanaele.setText("" + recorder.getChannelCount());
+
+ logger.log("Puffergroeße: "+ minPufferGroesseInBytes + " " + pufferGroesseInBytes);
+ logger.log("Recorder (SR, CH): "+ recorder.getSampleRate() + " " + recorder.getChannelCount());
+
+ int anzahlBytesProAbtastwert;
+ String s;
+ switch (recorder.getAudioFormat()) {
+ case AudioFormat.ENCODING_PCM_8BIT:
+ s = "8 Bit PCM ";
+ anzahlBytesProAbtastwert = 1;
+ break;
+ case AudioFormat.ENCODING_PCM_16BIT:
+ s = "16 Bit PCM";
+ anzahlBytesProAbtastwert = 2;
+ break;
+ case AudioFormat.ENCODING_PCM_FLOAT:
+ s = "Float PCM";
+ anzahlBytesProAbtastwert = 4;
+ break;
+ default:
+ throw new IllegalArgumentException();
+ }
+// textViewAudioFormat.setText(s);
+
+ switch (recorder.getChannelConfiguration()) {
+ case AudioFormat.CHANNEL_IN_MONO:
+ s = "Mono";
+ break;
+ case AudioFormat.CHANNEL_IN_STEREO:
+ s = "Stereo";
+ anzahlBytesProAbtastwert *= 2;
+ break;
+ case AudioFormat.CHANNEL_INVALID:
+ s = "ungültig";
+ break;
+ default:
+ throw new IllegalArgumentException();
+ }
+// textViewKanalKonfiguration.setText(s);
+ logger.log("Konfiguration: "+ s);
+
+ int pufferGroesseInAnzahlAbtastwerten = pufferGroesseInBytes / anzahlBytesProAbtastwert;
+ int pufferGroesseInMillisekunden = 1000 * pufferGroesseInAnzahlAbtastwerten / recorder.getSampleRate();
+
+// textViewPufferGroesseInAnzahlAbtastwerte.setText("" + pufferGroesseInAnzahlAbtastwerten);
+// textViewPufferGroesseInMillisekunden.setText("" + pufferGroesseInMillisekunden);
+ }
+
+ @Override
+ protected Void doInBackground(Long... params) {
+ recorder.startRecording();
+ short[] puffer = new short[pufferGroesseInBytes / 2];
+ long lastTime = System.currentTimeMillis();
+ float verarbeitungsrate = 0;
+ final int maxZaehlerZeitMessung = 10;
+ int zaehlerZeitMessung = 0;
+ int anzahlVerarbeitet = 0;
+ GleitenderMittelwert gleitenderMittelwert = new GleitenderMittelwert(0.3f);
+
+ //Kalibrierung
+ try {
+ Thread.sleep(3000);
+ } catch (InterruptedException e) {
+ e.printStackTrace();
+ }
+ int i = 0;
+ for (i = 0; i < 20; i++) {
+ int n = recorder.read(puffer, 0, puffer.length);
+ Verarbeitungsergebnis kalibrierErgebnis = verarbeiten(puffer, n);
+ kalibierWert += kalibrierErgebnis.maxAmp;
+ try {
+ Thread.sleep(50);
+ } catch (InterruptedException e) {
+ e.printStackTrace();
+ }
+ }
+ kalibierWert = kalibierWert/i;
+
+// Complex[] zeitSignal = new Complex[puffer.length];
+// for (int j = 0; j < puffer.length; j++) {
+// zeitSignal[j] = new Complex(puffer[j], 0);
+// }
+// Complex[] spektrum = FFT.fft(zeitSignal);
+ double[] spektrum = calculateFFT(puffer);
+ DataPoint AddPoint;
+// LineGraphSeries series = new LineGraphSeries(new DataPoint[]{});
+// for (i = 0; i < spektrum.length; i++) {
+// AddPoint = new DataPoint(i, spektrum[i]);
+// series.appendData(AddPoint, true, spektrum.length);
+// }
+// graph.addSeries(series);
+ // logger.log(spektrum.toString());
+
+ for (; ; ) {
+ if (aufnahmeTask.isCancelled()) {
+ break;
+ } else {
+ int n = recorder.read(puffer, 0, puffer.length);
+ Verarbeitungsergebnis ergebnis = verarbeiten(puffer, n);
+ anzahlVerarbeitet += n;
+
+ spektrum = calculateFFT(puffer);
+ LineGraphSeries newseries = new LineGraphSeries(new DataPoint[]{});
+ for (i = 0; i < spektrum.length; i++) {
+ AddPoint = new DataPoint(i, spektrum[i]);
+ newseries.appendData(AddPoint, true, spektrum.length);
+ }
+ graph.removeAllSeries();
+ graph.addSeries(newseries);
+ zaehlerZeitMessung++;
+ if (zaehlerZeitMessung == maxZaehlerZeitMessung) {
+ long time = System.currentTimeMillis();
+ long deltaTime = time - lastTime;
+ verarbeitungsrate = 1000.0f * anzahlVerarbeitet / deltaTime;
+ verarbeitungsrate = gleitenderMittelwert.mittel(verarbeitungsrate);
+ zaehlerZeitMessung = 0;
+ anzahlVerarbeitet = 0;
+ lastTime = time;
+ }
+
+
+ ergebnis.verarbeitungsrate = (int) verarbeitungsrate;
+ publishProgress(ergebnis);
+
+ try {
+ Thread.sleep(100);
+ } catch (InterruptedException e) {
+ e.printStackTrace();
+ }
+ }
+ }
+ recorder.release();
+ return null;
+ }
+
+ private Verarbeitungsergebnis verarbeiten(short[] daten, int n) {
+ String status;
+ short maxAmp = -1;
+ if (n == AudioRecord.ERROR_INVALID_OPERATION) {
+ status = "ERROR_INVALID_OPERATION";
+ } else if (n == AudioRecord.ERROR_BAD_VALUE) {
+ status = "ERROR_BAD_VALUE";
+ } else {
+ status = "OK";
+ short max = 0;
+ for (int i = 0; i < n; i++) {
+ if (daten[i] > max) {
+ max = daten[i];
+ //max = 20 * log10(abs(daten[i]) / 32768);
+ }
+ }
+
+ ringPuffer.hinzufuegen(max);
+ maxAmp = ringPuffer.maximum();
+ if (maxAmp <= Schwellwert_Alarm+kalibierWert) {
+ armed = true;
+ }
+ }
+
+ return new Verarbeitungsergebnis(status, maxAmp, 0);
+ }
+
+ @Override
+ protected void onProgressUpdate(Verarbeitungsergebnis... progress) {
+ super.onProgressUpdate(progress);
+// textViewMaxAmp.setText("" + progress[0].maxAmp);
+// textViewVerarbeitungsrate.setText("" + progress[0].verarbeitungsrate);
+ float maxAmpPrint = round(20*log10(abs(progress[0].maxAmp/1.0)));
+ float kalibierWertPrint = round(20*log10(abs(kalibierWert)));
+ logger.overwriteLastlog("VR, Max, Kal:" + progress[0].verarbeitungsrate + ", " + maxAmpPrint
+ + " dB, " + kalibierWertPrint + " dB");
+
+ if (progress[0].maxAmp >= Schwellwert_Alarm+kalibierWert && armed == true) {
+ armed = false;
+ detectionReport = new DetectionReport("Mic1", "Audio", maxAmpPrint);
+ logger.log("");
+ logger.log("Alarm!");
+ logger.log(detectionReport.toString());
+ logger.log("");
+ }
+ }
+ }
+
+ private double[] calculateFFT(short[] zeitsignal)
+ {
+ byte signal[] = new byte[zeitsignal.length];
+ // loops through all the values of a Short
+ for (int i = 0; i < zeitsignal.length-1; i++) {
+ signal[i] = (byte) (zeitsignal[i]);
+ signal[i+1] = (byte) (zeitsignal[i] >> 8);
+ }
+
+ final int mNumberOfFFTPoints =1024;
+ double mMaxFFTSample;
+
+ double temp;
+ Complex[] y;
+ Complex[] complexSignal = new Complex[mNumberOfFFTPoints];
+ double[] absSignal = new double[mNumberOfFFTPoints/2];
+
+ for(int i = 0; i < mNumberOfFFTPoints; i++){
+ temp = (double)((signal[2*i] & 0xFF) | (signal[2*i+1] << 8)) / 32768.0F;
+ complexSignal[i] = new Complex(temp,0.0);
+ }
+
+ y = FFT.fft(complexSignal);
+
+ mMaxFFTSample = 0.0;
+ // mPeakPos = 0;
+ for(int i = 0; i < (mNumberOfFFTPoints/2); i++)
+ {
+ absSignal[i] = y[i].abs();
+// absSignal[i] = Math.sqrt(Math.pow(y[i].re(), 2) + Math.pow(y[i].im(), 2));
+// if(absSignal[i] > mMaxFFTSample)
+// {
+// mMaxFFTSample = absSignal[i];
+// // mPeakPos = i;
+// }
+ }
+
+ return absSignal;
+
+ }
+
+ class Verarbeitungsergebnis {
+ String status;
+ short maxAmp;
+ int verarbeitungsrate;
+ Verarbeitungsergebnis(String status, short maxAmp, int verarbeitungsrate) {
+ this.status = status;
+ this.maxAmp = maxAmp;
+ this.verarbeitungsrate = verarbeitungsrate;
+ }
+ }
+
+ class RingPuffer {
+ private short[] puffer;
+ private final int laenge;
+ private int anzahlEnthaltenerDaten;
+ private int position;
+
+ public RingPuffer(int n) {
+ laenge = n;
+ anzahlEnthaltenerDaten = 0;
+ position = 0;
+ puffer = new short[laenge];
+ }
+
+ public void hinzufuegen(short wert) {
+ puffer[position] = wert;
+ position++;
+ if (position >= laenge) {
+ position = 0;
+ }
+ if (anzahlEnthaltenerDaten < laenge) {
+ anzahlEnthaltenerDaten++;
+ }
+ }
+
+ public void hinzufuegen(short[] daten) {
+ for (short d : daten) {
+ puffer[position] = d;
+ position++;
+ if (position >= laenge) {
+ position = 0;
+ }
+ }
+ if (anzahlEnthaltenerDaten < laenge) {
+ anzahlEnthaltenerDaten += daten.length;
+ if (anzahlEnthaltenerDaten >= laenge) {
+ anzahlEnthaltenerDaten = laenge;
+ }
+ }
+ }
+
+ public short maximum() {
+ short max = 0;
+ for (int i = 0; i < anzahlEnthaltenerDaten; i++) {
+ if (puffer[i] > max) {
+ max = puffer[i];
+ }
+ }
+ return max;
+ }
+
+ public float mittelwert() {
+ float summe = 0;
+ for (int i = 0; i < anzahlEnthaltenerDaten; i++) {
+ summe += puffer[i];
+ }
+ return summe / anzahlEnthaltenerDaten;
+ }
+ }
+
+ class GleitenderMittelwert {
+ private final float wichtungNeuerWert;
+ private final float wichtungAlterWert;
+ private float mittelwert = 0;
+ private boolean istMittelwertGesetzt = false;
+
+ GleitenderMittelwert(float wichtungNeuerWert) {
+ this.wichtungNeuerWert = wichtungNeuerWert;
+ this.wichtungAlterWert = 1 - this.wichtungNeuerWert;
+ }
+
+ float MittelwertPuffer(short[] puffer) {
+
+ for (int i = 0; i < puffer.length; i++) {
+ mittelwert = Math.abs(puffer[i]);
+ }
+ mittelwert = mittelwert/puffer.length;
+
+ return mittelwert;
+ }
+
+ float mittel(float wert) {
+ if (istMittelwertGesetzt) {
+ mittelwert = wert * wichtungNeuerWert + mittelwert * wichtungAlterWert;
+ } else {
+ mittelwert = wert;
+ istMittelwertGesetzt = true;
+ }
+ return mittelwert;
+ }
+ }
+}
diff --git a/app/src/main/java/com/example/ueberwachungssystem/Signalverarbeitung/Complex.java b/app/src/main/java/com/example/ueberwachungssystem/Signalverarbeitung/Complex.java
new file mode 100644
index 0000000..26a3c28
--- /dev/null
+++ b/app/src/main/java/com/example/ueberwachungssystem/Signalverarbeitung/Complex.java
@@ -0,0 +1,148 @@
+package com.example.ueberwachungssystem.Signalverarbeitung;
+
+import java.util.Objects;
+
+public class Complex {
+ private final double re; // the real part
+ private final double im; // the imaginary part
+
+ // create a new object with the given real and imaginary parts
+ public Complex(double real, double imag) {
+ re = real;
+ im = imag;
+ }
+
+ // return a string representation of the invoking com.example.ueberwachungssystem.Signalverarbeitung.Complex object
+ public String toString() {
+ if (im == 0) return re + "";
+ if (re == 0) return im + "i";
+ if (im < 0) return re + " - " + (-im) + "i";
+ return re + " + " + im + "i";
+ }
+
+ // return abs/modulus/magnitude
+ public double abs() {
+ return Math.hypot(re, im);
+ }
+
+ // return angle/phase/argument, normalized to be between -pi and pi
+ public double phase() {
+ return Math.atan2(im, re);
+ }
+
+ // return a new com.example.ueberwachungssystem.Signalverarbeitung.Complex object whose value is (this + b)
+ public Complex plus(Complex b) {
+ Complex a = this; // invoking object
+ double real = a.re + b.re;
+ double imag = a.im + b.im;
+ return new Complex(real, imag);
+ }
+
+ // return a new com.example.ueberwachungssystem.Signalverarbeitung.Complex object whose value is (this - b)
+ public Complex minus(Complex b) {
+ Complex a = this;
+ double real = a.re - b.re;
+ double imag = a.im - b.im;
+ return new Complex(real, imag);
+ }
+
+ // return a new com.example.ueberwachungssystem.Signalverarbeitung.Complex object whose value is (this * b)
+ public Complex times(Complex b) {
+ Complex a = this;
+ double real = a.re * b.re - a.im * b.im;
+ double imag = a.re * b.im + a.im * b.re;
+ return new Complex(real, imag);
+ }
+
+ // return a new object whose value is (this * alpha)
+ public Complex scale(double alpha) {
+ return new Complex(alpha * re, alpha * im);
+ }
+
+ // return a new com.example.ueberwachungssystem.Signalverarbeitung.Complex object whose value is the conjugate of this
+ public Complex conjugate() {
+ return new Complex(re, -im);
+ }
+
+ // return a new com.example.ueberwachungssystem.Signalverarbeitung.Complex object whose value is the reciprocal of this
+ public Complex reciprocal() {
+ double scale = re * re + im * im;
+ return new Complex(re / scale, -im / scale);
+ }
+
+ // return the real or imaginary part
+ public double re() {
+ return re;
+ }
+
+ public double im() {
+ return im;
+ }
+
+ // return a / b
+ public Complex divides(Complex b) {
+ Complex a = this;
+ return a.times(b.reciprocal());
+ }
+
+ // return a new com.example.ueberwachungssystem.Signalverarbeitung.Complex object whose value is the complex exponential of this
+ public Complex exp() {
+ return new Complex(Math.exp(re) * Math.cos(im), Math.exp(re) * Math.sin(im));
+ }
+
+ // return a new com.example.ueberwachungssystem.Signalverarbeitung.Complex object whose value is the complex sine of this
+ public Complex sin() {
+ return new Complex(Math.sin(re) * Math.cosh(im), Math.cos(re) * Math.sinh(im));
+ }
+
+ // return a new com.example.ueberwachungssystem.Signalverarbeitung.Complex object whose value is the complex cosine of this
+ public Complex cos() {
+ return new Complex(Math.cos(re) * Math.cosh(im), -Math.sin(re) * Math.sinh(im));
+ }
+
+ // return a new com.example.ueberwachungssystem.Signalverarbeitung.Complex object whose value is the complex tangent of this
+ public Complex tan() {
+ return sin().divides(cos());
+ }
+
+ // a static version of plus
+ public static Complex plus(Complex a, Complex b) {
+ double real = a.re + b.re;
+ double imag = a.im + b.im;
+ Complex sum = new Complex(real, imag);
+ return sum;
+ }
+
+ // See Section 3.3.
+ public boolean equals(Object x) {
+ if (x == null) return false;
+ if (this.getClass() != x.getClass()) return false;
+ Complex that = (Complex) x;
+ return (this.re == that.re) && (this.im == that.im);
+ }
+
+ // See Section 3.3.
+ public int hashCode() {
+ return Objects.hash(re, im);
+ }
+
+ // sample client for testing
+ public static void main(String[] args) {
+ Complex a = new Complex(5.0, 6.0);
+ Complex b = new Complex(-3.0, 4.0);
+
+ System.out.println("a = " + a);
+ System.out.println("b = " + b);
+ System.out.println("Re(a) = " + a.re());
+ System.out.println("Im(a) = " + a.im());
+ System.out.println("b + a = " + b.plus(a));
+ System.out.println("a - b = " + a.minus(b));
+ System.out.println("a * b = " + a.times(b));
+ System.out.println("b * a = " + b.times(a));
+ System.out.println("a / b = " + a.divides(b));
+ System.out.println("(a / b) * b = " + a.divides(b).times(b));
+ System.out.println("conj(a) = " + a.conjugate());
+ System.out.println("|a| = " + a.abs());
+ System.out.println("tan(a) = " + a.tan());
+ }
+}
\ No newline at end of file
diff --git a/app/src/main/java/com/example/ueberwachungssystem/Signalverarbeitung/FFT.java b/app/src/main/java/com/example/ueberwachungssystem/Signalverarbeitung/FFT.java
new file mode 100644
index 0000000..2543310
--- /dev/null
+++ b/app/src/main/java/com/example/ueberwachungssystem/Signalverarbeitung/FFT.java
@@ -0,0 +1,248 @@
+package com.example.ueberwachungssystem.Signalverarbeitung;
+// Source: https://introcs.cs.princeton.edu/java/97data/FFT.java.html
+
+import android.util.Log;
+
+/******************************************************************************
+ * Compilation: javac FFT.java
+ * Execution: java FFT n
+ * Dependencies: com.example.ueberwachungssystem.Signalverarbeitung.Complex.java
+ *
+ * Compute the FFT and inverse FFT of a length n complex sequence
+ * using the radix 2 Cooley-Tukey algorithm.
+ * Bare bones implementation that runs in O(n log n) time and O(n)
+ * space. Our goal is to optimize the clarity of the code, rather
+ * than performance.
+ *
+ * This implementation uses the primitive root of unity w = e^(-2 pi i / n).
+ * Some resources use w = e^(2 pi i / n).
+ *
+ * Reference: https://www.cs.princeton.edu/~wayne/kleinberg-tardos/pdf/05DivideAndConquerII.pdf
+ *
+ * Limitations
+ * -----------
+ * - assumes n is a power of 2
+ *
+ * - not the most memory efficient algorithm (because it uses
+ * an object type for representing complex numbers and because
+ * it re-allocates memory for the subarray, instead of doing
+ * in-place or reusing a single temporary array)
+ *
+ * For an in-place radix 2 Cooley-Tukey FFT, see
+ * https://introcs.cs.princeton.edu/java/97data/InplaceFFT.java.html
+ *
+ ******************************************************************************/
+
+public class FFT {
+
+ // compute the FFT of x[], assuming its length n is a power of 2
+ public static Complex[] fft(Complex[] x) {
+ int n = x.length;
+
+ // base case
+ if (n == 1) return new Complex[]{x[0]};
+
+ // radix 2 Cooley-Tukey FFT
+ if (n % 2 != 0) {
+ throw new IllegalArgumentException("n is not a power of 2");
+ }
+
+ // compute FFT of even terms
+ Complex[] even = new Complex[n / 2];
+ for (int k = 0; k < n / 2; k++) {
+ even[k] = x[2 * k];
+ }
+ Complex[] evenFFT = fft(even);
+
+ // compute FFT of odd terms
+ Complex[] odd = even; // reuse the array (to avoid n log n space)
+ for (int k = 0; k < n / 2; k++) {
+ odd[k] = x[2 * k + 1];
+ }
+ Complex[] oddFFT = fft(odd);
+
+ // combine
+ Complex[] y = new Complex[n];
+ for (int k = 0; k < n / 2; k++) {
+ double kth = -2 * k * Math.PI / n;
+ Complex wk = new Complex(Math.cos(kth), Math.sin(kth));
+ y[k] = evenFFT[k].plus(wk.times(oddFFT[k]));
+ y[k + n / 2] = evenFFT[k].minus(wk.times(oddFFT[k]));
+ }
+ return y;
+ }
+
+
+ // compute the inverse FFT of x[], assuming its length n is a power of 2
+ public static Complex[] ifft(Complex[] x) {
+ int n = x.length;
+ Complex[] y = new Complex[n];
+
+ // take conjugate
+ for (int i = 0; i < n; i++) {
+ y[i] = x[i].conjugate();
+ }
+
+ // compute forward FFT
+ y = fft(y);
+
+ // take conjugate again
+ for (int i = 0; i < n; i++) {
+ y[i] = y[i].conjugate();
+ }
+
+ // divide by n
+ for (int i = 0; i < n; i++) {
+ y[i] = y[i].scale(1.0 / n);
+ }
+
+ return y;
+
+ }
+
+ // compute the circular convolution of x and y
+ public static Complex[] cconvolve(Complex[] x, Complex[] y) {
+
+ // should probably pad x and y with 0s so that they have same length
+ // and are powers of 2
+ if (x.length != y.length) {
+ throw new IllegalArgumentException("Dimensions don't agree");
+ }
+
+ int n = x.length;
+
+ // compute FFT of each sequence
+ Complex[] a = fft(x);
+ Complex[] b = fft(y);
+
+ // point-wise multiply
+ Complex[] c = new Complex[n];
+ for (int i = 0; i < n; i++) {
+ c[i] = a[i].times(b[i]);
+ }
+
+ // compute inverse FFT
+ return ifft(c);
+ }
+
+
+ // compute the linear convolution of x and y
+ public static Complex[] convolve(Complex[] x, Complex[] y) {
+ Complex ZERO = new Complex(0, 0);
+
+ Complex[] a = new Complex[2 * x.length];
+ for (int i = 0; i < x.length; i++) a[i] = x[i];
+ for (int i = x.length; i < 2 * x.length; i++) a[i] = ZERO;
+
+ Complex[] b = new Complex[2 * y.length];
+ for (int i = 0; i < y.length; i++) b[i] = y[i];
+ for (int i = y.length; i < 2 * y.length; i++) b[i] = ZERO;
+
+ return cconvolve(a, b);
+ }
+
+ // compute the DFT of x[] via brute force (n^2 time)
+ public static Complex[] dft(Complex[] x) {
+ int n = x.length;
+ Complex ZERO = new Complex(0, 0);
+ Complex[] y = new Complex[n];
+ for (int k = 0; k < n; k++) {
+ y[k] = ZERO;
+ for (int j = 0; j < n; j++) {
+ int power = (k * j) % n;
+ double kth = -2 * power * Math.PI / n;
+ Complex wkj = new Complex(Math.cos(kth), Math.sin(kth));
+ y[k] = y[k].plus(x[j].times(wkj));
+ }
+ }
+ return y;
+ }
+
+ // display an array of com.example.ueberwachungssystem.Signalverarbeitung.Complex numbers to standard output
+ public static void show(Complex[] x, String title) {
+ System.out.println(title);
+ System.out.println("-------------------");
+ for (int i = 0; i < x.length; i++) {
+ System.out.println(x[i]);
+ }
+ System.out.println();
+ }
+
+ /***************************************************************************
+ * Test client and sample execution
+ *
+ * % java FFT 4
+ * x
+ * -------------------
+ * -0.03480425839330703
+ * 0.07910192950176387
+ * 0.7233322451735928
+ * 0.1659819820667019
+ *
+ * y = fft(x)
+ * -------------------
+ * 0.9336118983487516
+ * -0.7581365035668999 + 0.08688005256493803i
+ * 0.44344407521182005
+ * -0.7581365035668999 - 0.08688005256493803i
+ *
+ * z = ifft(y)
+ * -------------------
+ * -0.03480425839330703
+ * 0.07910192950176387 + 2.6599344570851287E-18i
+ * 0.7233322451735928
+ * 0.1659819820667019 - 2.6599344570851287E-18i
+ *
+ * c = cconvolve(x, x)
+ * -------------------
+ * 0.5506798633981853
+ * 0.23461407150576394 - 4.033186818023279E-18i
+ * -0.016542951108772352
+ * 0.10288019294318276 + 4.033186818023279E-18i
+ *
+ * d = convolve(x, x)
+ * -------------------
+ * 0.001211336402308083 - 3.122502256758253E-17i
+ * -0.005506167987577068 - 5.058885073636224E-17i
+ * -0.044092969479563274 + 2.1934338938072244E-18i
+ * 0.10288019294318276 - 3.6147323062478115E-17i
+ * 0.5494685269958772 + 3.122502256758253E-17i
+ * 0.240120239493341 + 4.655566391833896E-17i
+ * 0.02755001837079092 - 2.1934338938072244E-18i
+ * 4.01805098805014E-17i
+ *
+ ***************************************************************************/
+
+ public static void main(String[] args) {
+ int n = Integer.parseInt(args[0]);
+ Complex[] x = new Complex[n];
+
+ // original data
+ for (int i = 0; i < n; i++) {
+ x[i] = new Complex(i, 0);
+ }
+ show(x, "x");
+
+ // FFT of original data
+ Complex[] y = fft(x);
+ show(y, "y = fft(x)");
+
+ // FFT of original data
+ Complex[] y2 = dft(x);
+ show(y2, "y2 = dft(x)");
+
+ // take inverse FFT
+ Complex[] z = ifft(y);
+ show(z, "z = ifft(y)");
+
+ // circular convolution of x with itself
+ Complex[] c = cconvolve(x, x);
+ show(c, "c = cconvolve(x, x)");
+
+ // linear convolution of x with itself
+ Complex[] d = convolve(x, x);
+ show(d, "d = convolve(x, x)");
+ }
+}
+
+
diff --git a/app/src/main/java/com/example/ueberwachungssystem/logger/Logger.java b/app/src/main/java/com/example/ueberwachungssystem/logger/Logger.java
new file mode 100644
index 0000000..07af51a
--- /dev/null
+++ b/app/src/main/java/com/example/ueberwachungssystem/logger/Logger.java
@@ -0,0 +1,61 @@
+package com.example.ueberwachungssystem.logger;
+
+import android.util.Log;
+import android.widget.TextView;
+
+import java.io.PrintWriter;
+import java.io.StringWriter;
+
+public class Logger {
+ private TextView textView;
+ private StringBuffer sb = new StringBuffer();
+ private String tag;
+ private int lengthOfLastLog = 0;
+ private boolean overwrite = false;
+
+ public Logger(String tag, TextView textView, String logInitText) {
+ this.tag = tag;
+ this.textView = textView;
+ sb.append(logInitText);
+ }
+
+ public void log(String s) {
+ overwrite = false;
+ Log.d(tag, s);
+ sb.append(s).append("\n");
+ if (textView != null) {
+ textView.setText(sb.toString());
+ }
+ }
+
+ public void overwriteLastlog(String s) {
+ Log.d(tag, s);
+ lengthOfLastLog = s.length();
+ if (overwrite)
+ {
+ sb.setLength(sb.length() - (lengthOfLastLog + 1));
+ }
+ sb.append(s).append("\n");
+ overwrite = true;
+ if (textView != null) {
+ textView.setText(sb.toString());
+ }
+ }
+
+ public void log(Exception e) {
+ StringWriter sw = new StringWriter();
+ e.printStackTrace(new PrintWriter(sw));
+ log(sw.toString());
+ }
+
+ public void clearLog() {
+ sb.setLength(0);
+ if (textView != null) {
+ textView.setText("");
+ }
+ }
+
+ public String getLoggedText() {
+ return sb.toString();
+ }
+}
diff --git a/gradle.properties b/gradle.properties
index 3e927b1..92b9117 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -18,4 +18,5 @@ android.useAndroidX=true
# Enables namespacing of each library's R class so that its R class includes only the
# resources declared in the library itself and none from the library's dependencies,
# thereby reducing the size of the R class for that library
-android.nonTransitiveRClass=true
\ No newline at end of file
+android.nonTransitiveRClass=true
+android.enableJetifier=true
\ No newline at end of file