1 files changed, 98 insertions, 0 deletions
diff --git a/python/dpd/phase_align.py b/python/dpd/phase_align.py
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+++ b/python/dpd/phase_align.py
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+# -*- coding: utf-8 -*-
+#
+# DPD Computation Engine, phase-align a signal against a reference.
+#
+# http://www.opendigitalradio.org
+# Licence: The MIT License, see notice at the end of this file
+import datetime
+import os
+import logging
+import numpy as np
+import matplotlib.pyplot as plt
+
+
+def phase_align(sig, ref_sig, plot=False):
+    """Do phase alignment for sig relative to the reference signal
+    ref_sig.
+
+    Returns the aligned signal"""
+
+    angle_diff = (np.angle(sig) - np.angle(ref_sig)) % (2. * np.pi)
+
+    real_diffs = np.cos(angle_diff)
+    imag_diffs = np.sin(angle_diff)
+
+    if plot and self.c.plot_location is not None:
+        dt = datetime.datetime.now().isoformat()
+        fig_path = self.c.plot_location + "/" + dt + "_phase_align.png"
+
+        plt.subplot(511)
+        plt.hist(angle_diff, bins=60, label="Angle Diff")
+        plt.xlabel("Angle")
+        plt.ylabel("Count")
+        plt.legend(loc=4)
+
+        plt.subplot(512)
+        plt.hist(real_diffs, bins=60, label="Real Diff")
+        plt.xlabel("Real Part")
+        plt.ylabel("Count")
+        plt.legend(loc=4)
+
+        plt.subplot(513)
+        plt.hist(imag_diffs, bins=60, label="Imaginary Diff")
+        plt.xlabel("Imaginary Part")
+        plt.ylabel("Count")
+        plt.legend(loc=4)
+
+        plt.subplot(514)
+        plt.plot(np.angle(ref_sig[:128]), label="ref_sig")
+        plt.plot(np.angle(sig[:128]), label="sig")
+        plt.xlabel("Angle")
+        plt.ylabel("Sample")
+        plt.legend(loc=4)
+
+    real_diff = np.median(real_diffs)
+    imag_diff = np.median(imag_diffs)
+
+    angle = np.angle(real_diff + 1j * imag_diff)
+
+    logging.debug(
+        "Compensating phase by {} rad, {} degree. real median {}, imag median {}".format(
+        angle, angle*180./np.pi, real_diff, imag_diff
+    ))
+    sig = sig * np.exp(1j * -angle)
+
+    if logging.getLogger().getEffectiveLevel() == logging.DEBUG and plot:
+        plt.subplot(515)
+        plt.plot(np.angle(ref_sig[:128]), label="ref_sig")
+        plt.plot(np.angle(sig[:128]), label="sig")
+        plt.xlabel("Angle")
+        plt.ylabel("Sample")
+        plt.legend(loc=4)
+        plt.tight_layout()
+        plt.savefig(fig_path)
+        plt.close()
+
+    return sig
+
+# The MIT License (MIT)
+#
+# Copyright (c) 2017 Andreas Steger
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.