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Extracted Demodulator.normalizeFrequency()

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This commit is contained in:
Marek Ossowski 2025-08-21 00:34:25 +02:00
parent 8173f147d8
commit 4779d67180
1 changed files with 11 additions and 5 deletions
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16
app/src/main/java/xdsopl/robot36/Demodulator.java
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@ -13,6 +13,8 @@ public class Demodulator {
private final SchmittTrigger syncPulseTrigger;
private final Phasor baseBandOscillator;
private final Delay syncPulseValueDelay;
private final double scanLineBandwidth;
private final double centerFrequency;
private final float syncPulseFrequencyValue;
private final float syncPulseFrequencyTolerance;
private final int syncPulse5msMinSamples;
@ -38,7 +40,7 @@ public class Demodulator {
public static final double whiteFrequency = 2300;
Demodulator(int sampleRate) {
double scanLineBandwidth = whiteFrequency - blackFrequency;
scanLineBandwidth = whiteFrequency - blackFrequency;
frequencyModulation = new FrequencyModulation(scanLineBandwidth, sampleRate);
double syncPulse5msSeconds = 0.005;
double syncPulse9msSeconds = 0.009;
@ -65,19 +67,23 @@ public class Demodulator {
Kaiser kaiser = new Kaiser();
for (int i = 0; i < baseBandLowPass.length; ++i)
baseBandLowPass.taps[i] = (float) (kaiser.window(2.0, i, baseBandLowPass.length) * Filter.lowPass(cutoffFrequency, sampleRate, i, baseBandLowPass.length));
double centerFrequency = (lowestFrequency + highestFrequency) / 2;
centerFrequency = (lowestFrequency + highestFrequency) / 2;
baseBandOscillator = new Phasor(-centerFrequency, sampleRate);
syncPulseFrequencyValue = (float) ((syncPulseFrequency - centerFrequency) * 2 / scanLineBandwidth); //converts to range from -1 to 1
syncPulseFrequencyValue = (float) normalizeFrequency(syncPulseFrequency);
syncPulseFrequencyTolerance = (float) (50 * 2 / scanLineBandwidth);
double syncPorchFrequency = 1500;
double syncHighFrequency = (syncPulseFrequency + syncPorchFrequency) / 2;
double syncLowFrequency = (syncPulseFrequency + syncHighFrequency) / 2;
double syncLowValue = (syncLowFrequency - centerFrequency) * 2 / scanLineBandwidth;
double syncHighValue = (syncHighFrequency - centerFrequency) * 2 / scanLineBandwidth;
double syncLowValue = normalizeFrequency(syncLowFrequency);
double syncHighValue = normalizeFrequency(syncHighFrequency);
syncPulseTrigger = new SchmittTrigger((float) syncLowValue, (float) syncHighValue);
baseBand = new Complex();
}
private double normalizeFrequency(double frequency) {
return (frequency - centerFrequency) * 2 / scanLineBandwidth;
}
/**
* @return true if sync pulse detected
*/