am-am am-pm diagram in syncmeasurement.ipynb

1 files changed, 42 insertions, 0 deletions

diff --git a/src/dab_util.py b/src/dab_util.py
new file mode 100644
index 0000000..2ad2af6
--- /dev/null
+++ b/src/dab_util.py
@@ -0,0 +1,42 @@
+import numpy as np
+import scipy
+import matplotlib.pyplot as plt
+
+c = {
+        "bw":1536000
+        }
+
+def calc_fft(signal, fft_size = 1024, sampling_rate = 1, plot = False):
+    """returns one numpy array for the frequencies and one for the corresponding fft"""
+    signal_spectrum = np.fft.fftshift(np.fft.fft(signal, fft_size))
+    freqs = np.fft.fftshift(np.fft.fftfreq(fft_size, d=1./sampling_rate))
+    if plot == True:
+        plot_freq_spec(freqs, signal_spectrum)
+    return freqs, signal_spectrum
+
+def plot_freq_spec(freq, spec = None):
+    plt.figure(figsize=(10,5))
+    if spec == None:
+        plt.plot(freq)
+    else:
+        plt.plot(freq, np.abs(spec))
+
+def freq_to_fft_sample(freq, fft_size, sampling_rate):
+    freq_ratio = 1.0 * fft_size / sampling_rate
+    return int(freq * freq_ratio + fft_size / 2)
+
+def crop_signal(signal, n_window = 1000, n_zeros = 1000, debug = False):
+    #signal = signal[-10:-1]
+    mag = abs(signal)
+    window = np.ones(n_window) / float(n_window)
+    mag = scipy.signal.convolve(window, mag)
+    mag = scipy.signal.convolve(window, mag)
+    thr = 0.05 * np.max(mag)
+    idx_start = np.argmax(mag > thr)
+    idx_end = mag.shape[0] - np.argmax(np.flipud(mag > thr))
+    if debug:
+        plt.plot(mag < thr)
+        plt.plot((idx_start,idx_start), (0,0.1), color='g', linewidth=2)
+        plt.plot((idx_end,idx_end), (0,0.1), color='r', linewidth=2)
+    signal = signal[idx_start - n_zeros: idx_end + n_zeros]
+    return signal