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detect 5, 9 and 20 ms sync pulses

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This commit is contained in:
Ahmet Inan 2024-04-17 15:27:10 +02:00
parent 6d8ebca9da
commit 1a1f061e1c
2 changed files with 90 additions and 23 deletions
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102
app/src/main/java/xdsopl/robot36/Demodulator.java
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@ -8,7 +8,9 @@ package xdsopl.robot36;
public class Demodulator {
private final SimpleMovingAverage powerAvg;
private final ComplexMovingAverage syncPulseFilter;
private final ComplexMovingAverage syncPulse5msFilter;
private final ComplexMovingAverage syncPulse9msFilter;
private final ComplexMovingAverage syncPulse20msFilter;
private final ComplexMovingAverage scanLineFilter;
private final ComplexMovingAverage baseBandLowPass;
private final FrequencyModulation scanLineDemod;
@ -16,16 +18,31 @@ public class Demodulator {
private final Phasor syncPulseOscillator;
private final Phasor scanLineOscillator;
private final Phasor baseBandOscillator;
private final Delay syncPulseDelay;
private final Delay syncPulse5msDelay;
private final Delay syncPulse9msDelay;
private final Delay syncPulse20msDelay;
private final int syncPulseLowMark;
private final int syncPulseHighMark;
private float syncPulseMaxValue;
private int syncPulseMaxPosition;
private float syncPulse5msMaxValue;
private float syncPulse9msMaxValue;
private float syncPulse20msMaxValue;
private int syncPulse5msMaxPosition;
private int syncPulse9msMaxPosition;
private int syncPulse20msMaxPosition;
private int syncPulseCounter;
private Complex baseBand;
private Complex syncPulse;
private Complex syncPulse5ms;
private Complex syncPulse9ms;
private Complex syncPulse20ms;
private Complex scanLine;
public enum SyncPulseWidth {
FiveMilliSeconds,
NineMilliSeconds,
TwentyMilliSeconds
}
public SyncPulseWidth syncPulseWidth;
public int syncPulseOffset;
Demodulator(int sampleRate) {
@ -39,11 +56,17 @@ public class Demodulator {
float scanLineCutoff = scanLineBandwidth / 2;
int scanLineFilterSamples = (int) Math.round(0.443 * sampleRate / scanLineCutoff) | 1;
scanLineFilter = new ComplexMovingAverage(scanLineFilterSamples);
double syncPulseSeconds = 0.009;
int syncPulseSamples = (int) Math.round(syncPulseSeconds * sampleRate) | 1;
syncPulseLowMark = syncPulseSamples / 2;
syncPulseHighMark = syncPulseSamples * 2;
syncPulseFilter = new ComplexMovingAverage(syncPulseSamples);
double syncPulse5msSeconds = 0.005;
double syncPulse9msSeconds = 0.009;
double syncPulse20msSeconds = 0.020;
int syncPulse5msSamples = (int) Math.round(syncPulse5msSeconds * sampleRate) | 1;
int syncPulse9msSamples = (int) Math.round(syncPulse9msSeconds * sampleRate) | 1;
int syncPulse20msSamples = (int) Math.round(syncPulse20msSeconds * sampleRate) | 1;
syncPulseLowMark = syncPulse5msSamples / 2;
syncPulseHighMark = syncPulse20msSamples * 2;
syncPulse5msFilter = new ComplexMovingAverage(syncPulse5msSamples);
syncPulse9msFilter = new ComplexMovingAverage(syncPulse9msSamples);
syncPulse20msFilter = new ComplexMovingAverage(syncPulse20msSamples);
float lowestFrequency = 1100;
float highestFrequency = 2300;
float cutoffFrequency = (highestFrequency - lowestFrequency) / 2;
@ -55,11 +78,18 @@ public class Demodulator {
syncPulseOscillator = new Phasor(-(syncPulseFrequency - centerFrequency), sampleRate);
float grayFrequency = (blackFrequency + whiteFrequency) / 2;
scanLineOscillator = new Phasor(-(grayFrequency - centerFrequency), sampleRate);
int syncPulseDelaySamples = (powerWindowSamples - 1) / 2;
syncPulseDelay = new Delay(syncPulseDelaySamples);
int syncPulse5msDelaySamples = (powerWindowSamples - 1) / 2 - (syncPulse5msSamples - 1) / 2;
int syncPulse9msDelaySamples = (powerWindowSamples - 1) / 2 - (syncPulse9msSamples - 1) / 2;
int syncPulse20msDelaySamples = (powerWindowSamples - 1) / 2 - (syncPulse20msSamples - 1) / 2;
syncPulse5msDelay = new Delay(syncPulse5msDelaySamples);
syncPulse9msDelay = new Delay(syncPulse9msDelaySamples);
syncPulse20msDelay = new Delay(syncPulse20msDelaySamples);
syncPulseTrigger = new SchmittTrigger(0.17f, 0.19f);
baseBand = new Complex();
syncPulse = new Complex();
syncPulse5ms = new Complex();
syncPulse9ms = new Complex();
syncPulse20ms = new Complex();
scanLine = new Complex();
}
@ -67,28 +97,54 @@ public class Demodulator {
boolean syncPulseDetected = false;
for (int i = 0; i < buffer.length; ++i) {
baseBand = baseBandLowPass.avg(baseBand.set(buffer[i]).mul(baseBandOscillator.rotate()));
syncPulse = syncPulseFilter.avg(syncPulse.set(baseBand).mul(syncPulseOscillator.rotate()));
syncPulse = syncPulse.set(baseBand).mul(syncPulseOscillator.rotate());
syncPulse5ms = syncPulse5msFilter.avg(syncPulse5ms.set(syncPulse));
syncPulse9ms = syncPulse9msFilter.avg(syncPulse9ms.set(syncPulse));
syncPulse20ms = syncPulse20msFilter.avg(syncPulse20ms.set(syncPulse));
scanLine = scanLineFilter.avg(scanLine.set(baseBand).mul(scanLineOscillator.rotate()));
float syncPulseValue = syncPulseDelay.push(syncPulse.norm()) / powerAvg.avg(baseBand.norm());
float averagePower = powerAvg.avg(baseBand.norm());
float syncPulse5msValue = syncPulse5msDelay.push(syncPulse5ms.norm()) / averagePower;
float syncPulse9msValue = syncPulse9msDelay.push(syncPulse9ms.norm()) / averagePower;
float syncPulse20msValue = syncPulse20msDelay.push(syncPulse20ms.norm()) / averagePower;
float scanLineValue = scanLineDemod.demod(scanLine);
float scanLineLevel = Math.min(Math.max(0.5f * (scanLineValue + 1), 0), 1);
if (syncPulseTrigger.latch(syncPulseValue)) {
if (syncPulseMaxValue < syncPulseValue) {
syncPulseMaxValue = syncPulseValue;
syncPulseMaxPosition = syncPulseCounter;
if (syncPulseTrigger.latch(syncPulse5msValue)) {
if (syncPulse5msMaxValue < syncPulse5msValue) {
syncPulse5msMaxValue = syncPulse5msValue;
syncPulse5msMaxPosition = syncPulseCounter;
}
if (syncPulse9msMaxValue < syncPulse9msValue) {
syncPulse9msMaxValue = syncPulse9msValue;
syncPulse9msMaxPosition = syncPulseCounter;
}
if (syncPulse20msMaxValue < syncPulse20msValue) {
syncPulse20msMaxValue = syncPulse20msValue;
syncPulse20msMaxPosition = syncPulseCounter;
}
++syncPulseCounter;
} else if (syncPulseCounter > syncPulseLowMark && syncPulseCounter < syncPulseHighMark) {
int filterDelay = (powerAvg.length - 1) / 2
+ (syncPulseFilter.length - 1) / 2
- (scanLineFilter.length - 1) / 2;
syncPulseOffset = i + syncPulseMaxPosition - syncPulseCounter - filterDelay;
int filterDelay = (powerAvg.length - 1) / 2 - (scanLineFilter.length - 1) / 2;
syncPulseOffset = i - syncPulseCounter - filterDelay;
if (syncPulse20msMaxValue > (9.f / 20.f) * syncPulse9msMaxValue) {
syncPulseOffset += syncPulse20msMaxPosition;
syncPulseWidth = SyncPulseWidth.TwentyMilliSeconds;
} else if (syncPulse9msMaxValue > (5.f / 9.f) * syncPulse5msMaxValue) {
syncPulseOffset += syncPulse9msMaxPosition;
syncPulseWidth = SyncPulseWidth.NineMilliSeconds;
} else {
syncPulseOffset += syncPulse5msMaxPosition;
syncPulseWidth = SyncPulseWidth.FiveMilliSeconds;
}
syncPulseDetected = true;
syncPulseCounter = 0;
syncPulseMaxValue = 0;
syncPulse5msMaxValue = 0;
syncPulse9msMaxValue = 0;
syncPulse20msMaxValue = 0;
} else {
syncPulseCounter = 0;
syncPulseMaxValue = 0;
syncPulse5msMaxValue = 0;
syncPulse9msMaxValue = 0;
syncPulse20msMaxValue = 0;
}
buffer[i] = scanLineLevel;
}

11
app/src/main/java/xdsopl/robot36/MainActivity.java
View file

@ -87,6 +87,17 @@ public class MainActivity extends AppCompatActivity {
}
}
if (syncPulseDetected && syncPulseIndex >= 0) {
switch (demodulator.syncPulseWidth) {
case FiveMilliSeconds:
status.setText("5 ms sync pulse");
break;
case NineMilliSeconds:
status.setText("9 ms sync pulse");
break;
case TwentyMilliSeconds:
status.setText("20 ms sync pulse");
break;
}
processOneLine(syncPulseIndex);
int count = curSample - syncPulseIndex;
curSample = 0;