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authorMatthias P. Braendli <matthias.braendli@mpb.li>2018-12-04 10:18:33 +0100
committerMatthias P. Braendli <matthias.braendli@mpb.li>2018-12-04 10:18:33 +0100
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+# -*- coding: utf-8 -*-
+#
+# Automatic Gain Control
+#
+# http://www.opendigitalradio.org
+# Licence: The MIT License, see notice at the end of this file
+
+import datetime
+import os
+import logging
+import time
+import numpy as np
+import matplotlib
+matplotlib.use('agg')
+import matplotlib.pyplot as plt
+
+import src.Adapt as Adapt
+import src.Measure as Measure
+
+class Agc:
+ """The goal of the automatic gain control is to set the
+ RX gain to a value at which all received amplitudes can
+ be detected. This means that the maximum possible amplitude
+ should be quantized at the highest possible digital value.
+
+ A problem we have to face, is that the estimation of the
+ maximum amplitude by applying the max() function is very
+ unstable. This is due to the maximum’s rareness. Therefore
+ we estimate a far more robust value, such as the median,
+ and then approximate the maximum amplitude from it.
+
+ Given this, we tune the RX gain in such a way, that the
+ received signal fulfills our desired property, of having
+ all amplitudes properly quantized."""
+
+ def __init__(self, measure, adapt, c):
+ assert isinstance(measure, Measure.Measure)
+ assert isinstance(adapt, Adapt.Adapt)
+ self.measure = measure
+ self.adapt = adapt
+ self.min_rxgain = c.RAGC_min_rxgain
+ self.rxgain = self.min_rxgain
+ self.peak_to_median = 1./c.RAGC_rx_median_target
+
+ def run(self):
+ self.adapt.set_rxgain(self.rxgain)
+
+ for i in range(2):
+ # Measure
+ txframe_aligned, tx_ts, rxframe_aligned, rx_ts, rx_median= \
+ self.measure.get_samples()
+
+ # Estimate Maximum
+ rx_peak = self.peak_to_median * rx_median
+ correction_factor = 20*np.log10(1/rx_peak)
+ self.rxgain = self.rxgain + correction_factor
+
+ assert self.min_rxgain <= self.rxgain, ("Desired RX Gain is {} which is smaller than the minimum of {}".format(
+ self.rxgain, self.min_rxgain))
+
+ logging.info("RX Median {:1.4f}, estimated peak {:1.4f}, correction factor {:1.4f}, new RX gain {:1.4f}".format(
+ rx_median, rx_peak, correction_factor, self.rxgain
+ ))
+
+ self.adapt.set_rxgain(self.rxgain)
+ time.sleep(0.5)
+
+ def plot_estimates(self):
+ """Plots the estimate of for Max, Median, Mean for different
+ number of samples."""
+ if self.c.plot_location is None:
+ return
+
+ self.adapt.set_rxgain(self.min_rxgain)
+ time.sleep(1)
+
+ dt = datetime.datetime.now().isoformat()
+ fig_path = self.c.plot_location + "/" + dt + "_agc.png"
+ fig, axs = plt.subplots(2, 2, figsize=(3*6,1*6))
+ axs = axs.ravel()
+
+ for j in range(5):
+ txframe_aligned, tx_ts, rxframe_aligned, rx_ts, rx_median =\
+ self.measure.get_samples()
+
+ rxframe_aligned_abs = np.abs(rxframe_aligned)
+
+ x = np.arange(100, rxframe_aligned_abs.shape[0], dtype=int)
+ rx_max_until = []
+ rx_median_until = []
+ rx_mean_until = []
+ for i in x:
+ rx_max_until.append(np.max(rxframe_aligned_abs[:i]))
+ rx_median_until.append(np.median(rxframe_aligned_abs[:i]))
+ rx_mean_until.append(np.mean(rxframe_aligned_abs[:i]))
+
+ axs[0].plot(x,
+ rx_max_until,
+ label="Run {}".format(j+1),
+ color=matplotlib.colors.hsv_to_rgb((1./(j+1.),0.8,0.7)),
+ linestyle="-", linewidth=0.25)
+ axs[0].set_xlabel("Samples")
+ axs[0].set_ylabel("Amplitude")
+ axs[0].set_title("Estimation for Maximum RX Amplitude")
+ axs[0].legend()
+
+ axs[1].plot(x,
+ rx_median_until,
+ label="Run {}".format(j+1),
+ color=matplotlib.colors.hsv_to_rgb((1./(j+1.),0.9,0.7)),
+ linestyle="-", linewidth=0.25)
+ axs[1].set_xlabel("Samples")
+ axs[1].set_ylabel("Amplitude")
+ axs[1].set_title("Estimation for Median RX Amplitude")
+ axs[1].legend()
+ ylim_1 = axs[1].get_ylim()
+
+ axs[2].plot(x,
+ rx_mean_until,
+ label="Run {}".format(j+1),
+ color=matplotlib.colors.hsv_to_rgb((1./(j+1.),0.9,0.7)),
+ linestyle="-", linewidth=0.25)
+ axs[2].set_xlabel("Samples")
+ axs[2].set_ylabel("Amplitude")
+ axs[2].set_title("Estimation for Mean RX Amplitude")
+ ylim_2 = axs[2].get_ylim()
+ axs[2].legend()
+
+ axs[1].set_ylim(min(ylim_1[0], ylim_2[0]),
+ max(ylim_1[1], ylim_2[1]))
+
+ fig.tight_layout()
+ fig.savefig(fig_path)
+
+ axs[3].hist(rxframe_aligned_abs, bins=60)
+ axs[3].set_xlabel("Amplitude")
+ axs[3].set_ylabel("Frequency")
+ axs[3].set_title("Histogram of Amplitudes")
+ axs[3].legend()
+
+ fig.tight_layout()
+ fig.savefig(fig_path)
+ plt.close(fig)
+
+
+# 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.