From d65b9c1fd4481b3cca6f1d62b11e8bb87ee27e1f Mon Sep 17 00:00:00 2001
From: Jono Targett <jono.targett@gmail.com>
Date: Sat, 25 May 2024 15:43:00 +0930
Subject: [PATCH] Added a version of selcald that actually works

---
 scripts/selcal-detect.py | 116 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 116 insertions(+)
 create mode 100755 scripts/selcal-detect.py

diff --git a/scripts/selcal-detect.py b/scripts/selcal-detect.py
new file mode 100755
index 0000000..d12b29b
--- /dev/null
+++ b/scripts/selcal-detect.py
@@ -0,0 +1,116 @@
+#! /usr/bin/env python3
+
+import csv
+import sys
+import numpy as np
+from scipy import signal
+import matplotlib.pyplot as plt
+from scipy.io import wavfile
+from scipy.signal import butter, lfilter
+from math import log10
+import pyqtgraph as pg
+from PyQt5 import QtWidgets
+
+tones = {}
+with open('tones.csv', newline='') as csvfile:
+    reader = csv.DictReader(csvfile)
+    for row in reader:
+        tones[row['designator']] = float(row['frequency'])
+
+
+# Shamelessly lifted from
+# https://scipy.github.io/old-wiki/pages/Cookbook/ButterworthBandpass
+def butter_bandpass(lowcut, highcut, fs, order=5):
+    nyq = 0.5 * fs
+    low = lowcut / nyq
+    high = highcut / nyq
+    b, a = butter(order, [low, high], btype='band')
+    return b, a
+
+def butter_bandpass_filter(data, lowcut, highcut, fs, order=5):
+    b, a = butter_bandpass(lowcut, highcut, fs, order=order)
+    y = lfilter(b, a, data)
+    return y
+
+# tone synthesis
+def note(freq, cycles, amp=32767.0, rate=44100):
+    len = cycles * (1.0/rate)
+    t = np.linspace(0, len, int(len * rate))
+    if freq == 0:
+        data = np.zeros(int(len * rate))
+    else:
+        data = np.sin(2 * np.pi * freq * t) * amp
+    return data.astype(int)
+
+def decimate_from_sample_rate(sample_rate):
+    if sample_rate == 44100:
+        return 4  # rate = 11025, Fmax = 5512.5 Hz
+    elif sample_rate == 48000:
+        return 5  # rate = 9600, Fmax = 4800 Hz
+    elif sample_rate == 22050:
+        return 2  # rate = 11025, Fmax = 5512.5 Hz
+    elif sample_rate == 11025:
+        return 1  # rate = 11025, Fmax = 5512.5 Hz
+    else:
+        raise ValueError("Sample rate not supported")
+
+
+# analyze wav file
+if __name__ == '__main__':
+    FLT_LEN = 2000  # Samples
+
+    file_name = sys.argv[1]
+    sample_rate, data = wavfile.read(file_name)
+
+    print(f"{file_name}: {len(data)} samples @ {sample_rate} Hz")
+
+    decimate = decimate_from_sample_rate(sample_rate)
+    if decimate > 1:
+        data = signal.decimate(data, decimate)
+        sample_rate = sample_rate / decimate
+
+    print(f'Length after decimation: {len(data)} samples')
+
+    data = butter_bandpass_filter(data, 270, 1700, sample_rate, order=8)
+
+    pure_signals = {tone:note(freq, FLT_LEN, rate=sample_rate) for tone,freq in tones.items()}
+    correlations = {tone:np.abs(signal.correlate(data, pure, mode='same')) for tone,pure in pure_signals.items()}
+
+
+    app = QtWidgets.QApplication([])
+    win = pg.GraphicsLayoutWidget(show=True, title="SELCAL Tone Correlation")
+
+    plot = win.addPlot(title=file_name)
+    plot.addLegend()
+
+    color_map = pg.colormap.get('CET-C6s')
+    colors = color_map.getLookupTable(nPts=len(tones))
+
+    for (tone, correlation), color in zip(correlations.items(), colors):
+        plot.plot(correlation, pen=pg.mkPen(color=color), fillLevel=0, name=tone)
+
+    plot.setLabel('left', 'Signal Correlation')
+    plot.setLabel('bottom', 'Time (samples)')
+
+    plot.showGrid(x=True, y=True)
+
+    app.exec_()
+
+    # matplotlib is too slow
+    '''
+    fig, ax = plt.subplots()
+
+    # Step 4: Plot the data
+    for tone,correlation in correlations.items():
+        ax.plot(correlation, label=tone)
+
+    # Step 5: Customize the plot
+    ax.set_title('Multiple Lines Sharing the Same X Data')
+    ax.set_xlabel('Time (samples)')
+    ax.set_ylabel('Signal Correlation')
+    ax.legend()  # Add a legend
+    ax.grid(True)  # Add a grid
+
+    # Step 6: Display the plot
+    plt.show()
+    '''
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