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#!/usr/bin/env python
#
# Copyright 2011-2013 Free Software Foundation, Inc.
#
# This file is part of GNU Radio
#
# SPDX-License-Identifier: GPL-3.0-or-later
#
#
from gnuradio import gr, digital, filter
from gnuradio import blocks
from gnuradio import channels
from gnuradio import eng_notation
from gnuradio.eng_arg import eng_float, intx
from argparse import ArgumentParser
import sys
import numpy
try:
from matplotlib import pyplot
except ImportError:
print("Error: could not import pyplot (http://matplotlib.sourceforge.net/)")
sys.exit(1)
class example_costas(gr.top_block):
def __init__(self, N, sps, rolloff, ntaps, bw, noise, foffset, toffset, poffset):
gr.top_block.__init__(self)
rrc_taps = filter.firdes.root_raised_cosine(
sps, sps, 1.0, rolloff, ntaps)
data = 2.0 * numpy.random.randint(0, 2, N) - 1.0
data = numpy.exp(1j * poffset) * data
self.src = blocks.vector_source_c(data.tolist(), False)
self.rrc = filter.interp_fir_filter_ccf(sps, rrc_taps)
self.chn = channels.channel_model(noise, foffset, toffset)
self.cst = digital.costas_loop_cc(bw, 2)
self.vsnk_src = blocks.vector_sink_c()
self.vsnk_cst = blocks.vector_sink_c()
self.vsnk_frq = blocks.vector_sink_f()
self.connect(self.src, self.rrc, self.chn, self.cst, self.vsnk_cst)
self.connect(self.rrc, self.vsnk_src)
self.connect((self.cst, 1), self.vsnk_frq)
def main():
parser = ArgumentParser(conflict_handler="resolve")
parser.add_argument("-N", "--nsamples", type=int, default=2000,
help="Set the number of samples to process [default=%(default)r]")
parser.add_argument("-S", "--sps", type=int, default=4,
help="Set the samples per symbol [default=%(default)r]")
parser.add_argument("-r", "--rolloff", type=eng_float, default=0.35,
help="Set the rolloff factor [default=%(default)r]")
parser.add_argument("-W", "--bandwidth", type=eng_float, default=2 * numpy.pi / 100.0,
help="Set the loop bandwidth [default=%(default)r]")
parser.add_argument("-n", "--ntaps", type=int, default=45,
help="Set the number of taps in the filters [default=%(default)r]")
parser.add_argument("--noise", type=eng_float, default=0.0,
help="Set the simulation noise voltage [default=%(default)r]")
parser.add_argument("-f", "--foffset", type=eng_float, default=0.0,
help="Set the simulation's normalized frequency offset (in Hz) [default=%(default)r]")
parser.add_argument("-t", "--toffset", type=eng_float, default=1.0,
help="Set the simulation's timing offset [default=%(default)r]")
parser.add_argument("-p", "--poffset", type=eng_float, default=0.707,
help="Set the simulation's phase offset [default=%(default)r]")
args = parser.parse_args()
# Adjust N for the interpolation by sps
args.nsamples = args.nsamples // args.sps
# Set up the program-under-test
put = example_costas(args.nsamples, args.sps, args.rolloff,
args.ntaps, args.bandwidth, args.noise,
args.foffset, args.toffset, args.poffset)
put.run()
data_src = numpy.array(put.vsnk_src.data())
# Convert the FLL's LO frequency from rads/sec to Hz
data_frq = numpy.array(put.vsnk_frq.data()) / (2.0 * numpy.pi)
# adjust this to align with the data.
data_cst = numpy.array(3 * [0, ] + list(put.vsnk_cst.data()))
# Plot the Costas loop's LO frequency
f1 = pyplot.figure(1, figsize=(12, 10), facecolor='w')
s1 = f1.add_subplot(2, 2, 1)
s1.plot(data_frq)
s1.set_title("Costas LO")
s1.set_xlabel("Samples")
s1.set_ylabel("Frequency (normalized Hz)")
# Plot the IQ symbols
s3 = f1.add_subplot(2, 2, 2)
s3.plot(data_src.real, data_src.imag, "o")
s3.plot(data_cst.real, data_cst.imag, "rx")
s3.set_title("IQ")
s3.set_xlabel("Real part")
s3.set_ylabel("Imag part")
s3.set_xlim([-2, 2])
s3.set_ylim([-2, 2])
# Plot the symbols in time
s4 = f1.add_subplot(2, 2, 3)
s4.set_position([0.125, 0.05, 0.775, 0.4])
s4.plot(data_src.real, "o-")
s4.plot(data_cst.real, "rx-")
s4.set_title("Symbols")
s4.set_xlabel("Samples")
s4.set_ylabel("Real Part of Signals")
pyplot.show()
if __name__ == "__main__":
try:
main()
except KeyboardInterrupt:
pass
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