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do the processing in the base band

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Ahmet Inan 2024-04-15 10:24:25 +02:00
parent 8beb5ccdc5
commit b8441694a6
2 changed files with 48 additions and 8 deletions
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27
app/src/main/java/xdsopl/robot36/ComplexDelay.java Normal file
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@ -0,0 +1,27 @@
/*
Complex digital delay line
Copyright 2024 Ahmet Inan <xdsopl@gmail.com>
*/
package xdsopl.robot36;
public class ComplexDelay {
public final int length;
private final Delay real;
private final Delay imag;
private final Complex temp;
ComplexDelay(int length) {
this.length = length;
this.real = new Delay(length);
this.imag = new Delay(length);
this.temp = new Complex();
}
Complex push(Complex input) {
temp.real = real.push(input.real);
temp.imag = imag.push(input.imag);
return temp;
}
}

29
app/src/main/java/xdsopl/robot36/MainActivity.java
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@ -37,11 +37,14 @@ public class MainActivity extends AppCompatActivity {
private float[] recordBuffer; private float[] recordBuffer;
private AudioRecord audioRecord; private AudioRecord audioRecord;
private TextView status; private TextView status;
private Delay powerDelay; private ComplexDelay powerDelay;
private SimpleMovingAverage powerAvg; private SimpleMovingAverage powerAvg;
private ComplexMovingAverage syncAvg; private ComplexMovingAverage syncAvg;
private Phasor osc_1200; private ComplexMovingAverage baseBandLowPass;
private Complex sad; private Phasor syncPulseOscillator;
private Phasor baseBandOscillator;
private Complex baseBand;
private Complex syncPulse;
private int tint; private int tint;
private int curLine; private int curLine;
@ -63,8 +66,9 @@ public class MainActivity extends AppCompatActivity {
private void processSamples() { private void processSamples() {
for (float v : recordBuffer) { for (float v : recordBuffer) {
sad = syncAvg.avg(sad.set(powerDelay.push(v)).mul(osc_1200.rotate())); baseBand = baseBandLowPass.avg(baseBand.set(v).mul(baseBandOscillator.rotate()));
float level = sad.norm() / powerAvg.avg(v * v); syncPulse = syncAvg.avg(powerDelay.push(baseBand).mul(syncPulseOscillator.rotate()));
float level = syncPulse.norm() / powerAvg.avg(baseBand.norm());
int x = Math.min((int) (scopeWidth * level), scopeWidth); int x = Math.min((int) (scopeWidth * level), scopeWidth);
for (int i = 0; i < x; ++i) for (int i = 0; i < x; ++i)
scopePixels[scopeWidth * curLine + i] = tint; scopePixels[scopeWidth * curLine + i] = tint;
@ -82,12 +86,21 @@ public class MainActivity extends AppCompatActivity {
double powerWindowSeconds = 0.5; double powerWindowSeconds = 0.5;
int powerWindowSamples = (int) Math.round(powerWindowSeconds * sampleRate) | 1; int powerWindowSamples = (int) Math.round(powerWindowSeconds * sampleRate) | 1;
powerAvg = new SimpleMovingAverage(powerWindowSamples); powerAvg = new SimpleMovingAverage(powerWindowSamples);
powerDelay = new Delay((powerWindowSamples - 1) / 2); powerDelay = new ComplexDelay((powerWindowSamples - 1) / 2);
double syncPulseSeconds = 0.009; double syncPulseSeconds = 0.009;
int syncPulseSamples = (int) Math.round(syncPulseSeconds * sampleRate); int syncPulseSamples = (int) Math.round(syncPulseSeconds * sampleRate);
syncAvg = new ComplexMovingAverage(syncPulseSamples); syncAvg = new ComplexMovingAverage(syncPulseSamples);
osc_1200 = new Phasor(-1200, sampleRate); float lowestFrequency = 1100;
sad = new Complex(); float highestFrequency = 2300;
float cutoffFrequency = (highestFrequency - lowestFrequency) / 2;
int lowPassSamples = (int) Math.round(0.443 * sampleRate / cutoffFrequency) | 1;
baseBandLowPass = new ComplexMovingAverage(lowPassSamples);
float centerFrequency = (lowestFrequency + highestFrequency) / 2;
baseBandOscillator = new Phasor(-centerFrequency, sampleRate);
float syncPulseFrequency = 1200;
syncPulseOscillator = new Phasor(-(syncPulseFrequency - centerFrequency), sampleRate);
baseBand = new Complex();
syncPulse = new Complex();
} }
private void initAudioRecord() { private void initAudioRecord() {