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Diffstat (limited to 'dpd/src')
| -rw-r--r-- | dpd/src/MER.py | 133 |
1 files changed, 133 insertions, 0 deletions
diff --git a/dpd/src/MER.py b/dpd/src/MER.py new file mode 100644 index 0000000..54ef6c6 --- /dev/null +++ b/dpd/src/MER.py @@ -0,0 +1,133 @@ +# -*- coding: utf-8 -*- +# +# Modulation Error Rate +# +# http://www.opendigitalradio.org +# Licence: The MIT License, see notice at the end of this file + +import datetime +import os +import logging +try: + logging_path = os.path.dirname(logging.getLoggerClass().root.handlers[0].baseFilename) +except: + logging_path = "/tmp/" + +import src.const +import numpy as np +import matplotlib +matplotlib.use('agg') +import matplotlib.pyplot as plt + +class MER: + def __init__(self, sample_rate): + self.c = src.const.const(sample_rate) + + def _calc_spectrum(self, tx): + fft = np.fft.fftshift(np.fft.fft(tx)) + return np.delete(fft[self.c.FFT_start:self.c.FFT_end], + self.c.FFT_delete) + + def _split_in_carrier(self, x, y): + if 0.5 < np.mean((np.abs(np.abs(x) - np.abs(y)) / + np.abs(np.abs(x) + np.abs(y)))): + # Constellation points are axis aligned on the Im/Re plane + x1 = x[(y < x) & (y > -x)] + y1 = y[(y < x) & (y > -x)] + + x2 = x[(y > x) & (y > -x)] + y2 = y[(y > x) & (y > -x)] + + x3 = x[(y > x) & (y < -x)] + y3 = y[(y > x) & (y < -x)] + + x4 = x[(y < x) & (y < -x)] + y4 = y[(y < x) & (y < -x)] + else: + # Constellation points are on the diagonal or Im/Re plane + x1 = x[(+x > 0) & (+y > 0)] + y1 = y[(+x > 0) & (+y > 0)] + + x2 = x[(-x > 0) & (+y > 0)] + y2 = y[(-x > 0) & (+y > 0)] + + x3 = x[(-x > 0) & (-y > 0)] + y3 = y[(-x > 0) & (-y > 0)] + + x4 = x[(+x > 0) & (-y > 0)] + y4 = y[(+x > 0) & (-y > 0)] + return (x1, y1), (x2, y2), (x3, y3), (x4, y4) + + def _calc_mer_for_isolated_constellation_point(self, x, y): + """Calculate MER for one constellation point""" + x_mean = np.mean(x) + y_mean = np.mean(y) + + U_RMS = np.sqrt(x_mean ** 2 + y_mean ** 2) + U_ERR = np.mean(np.sqrt((x - x_mean) ** 2 + (y - y_mean) ** 2)) + MER = 20 * np.log10(U_ERR / U_RMS) + + return x_mean, y_mean, U_RMS, U_ERR, MER + + def calc_mer(self, tx, debug=False): + assert tx.shape[0] == self.c.T_U,\ + "Wrong input length" + + spectrum = self._calc_spectrum(tx) + + dt = datetime.datetime.now().isoformat() + fig_path = logging_path + "/" + dt + "_MER.pdf" + + MERs = [] + for i, (x, y) in enumerate(self._split_in_carrier( + np.real(spectrum), + np.imag(spectrum))): + x_mean, y_mean, U_RMS, U_ERR, MER =\ + self._calc_mer_for_isolated_constellation_point(x, y) + MERs.append(MER) + + tau = np.linspace(0, 2 * np.pi, num=100) + x_err = U_ERR * np.sin(tau) + x_mean + y_err = U_ERR * np.cos(tau) + y_mean + + if debug: + ax = plt.subplot(221 + i) + ax.scatter(x, y, s=0.2, color='black') + ax.plot(x_mean, y_mean, 'p', color='red') + ax.plot(x_err, y_err, linewidth=2, color='blue') + ax.text(0.1, 0.1, "MER {:.1f}dB".format(MER), transform=ax.transAxes) + ax.set_xlabel("Real") + ax.set_ylabel("Imag") + ylim = ax.get_ylim() + ax.set_ylim(ylim[0] - (ylim[1] - ylim[0]) * 0.1, ylim[1]) + + if debug: + plt.tight_layout() + plt.savefig(fig_path) + plt.show() + plt.clf() + + MER_res = 20 * np.log10(np.mean([10 ** (MER / 20) for MER in MERs])) + return MER_res + +# 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. |