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chirp_channelize.py
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#!/usr/bin/env python
#
# Copyright 2009,2012,2013 Free Software Foundation, Inc.
#
# This file is part of GNU Radio
#
# SPDX-License-Identifier: GPL-3.0-or-later
#
#
from __future__ import print_function
from __future__ import division
from __future__ import unicode_literals
from gnuradio import gr
from gnuradio import blocks
from gnuradio import filter
import sys, time
import numpy
try:
from gnuradio import analog
except ImportError:
sys.stderr.write("Error: Program requires gr-analog.\n")
sys.exit(1)
try:
import pylab
from pylab import mlab
except ImportError:
sys.stderr.write("Error: Program requires matplotlib (see: matplotlib.sourceforge.net).\n")
sys.exit(1)
class pfb_top_block(gr.top_block):
def __init__(self):
gr.top_block.__init__(self)
self._N = 200000 # number of samples to use
self._fs = 9000 # initial sampling rate
self._M = 9 # Number of channels to channelize
# Create a set of taps for the PFB channelizer
self._taps = filter.firdes.low_pass_2(1, self._fs, 500, 20,
attenuation_dB=10,
window=filter.firdes.WIN_BLACKMAN_hARRIS)
# Calculate the number of taps per channel for our own information
tpc = numpy.ceil(float(len(self._taps)) / float(self._M))
print("Number of taps: ", len(self._taps))
print("Number of channels: ", self._M)
print("Taps per channel: ", tpc)
repeated = True
if(repeated):
self.vco_input = analog.sig_source_f(self._fs, analog.GR_SIN_WAVE, 0.25, 110)
else:
amp = 100
data = numpy.arange(0, amp, amp / float(self._N))
self.vco_input = blocks.vector_source_f(data, False)
# Build a VCO controlled by either the sinusoid or single chirp tone
# Then convert this to a complex signal
self.vco = blocks.vco_f(self._fs, 225, 1)
self.f2c = blocks.float_to_complex()
self.head = blocks.head(gr.sizeof_gr_complex, self._N)
# Construct the channelizer filter
self.pfb = filter.pfb.channelizer_ccf(self._M, self._taps)
# Construct a vector sink for the input signal to the channelizer
self.snk_i = blocks.vector_sink_c()
# Connect the blocks
self.connect(self.vco_input, self.vco, self.f2c)
self.connect(self.f2c, self.head, self.pfb)
self.connect(self.f2c, self.snk_i)
# Create a vector sink for each of M output channels of the filter and connect it
self.snks = list()
for i in range(self._M):
self.snks.append(blocks.vector_sink_c())
self.connect((self.pfb, i), self.snks[i])
def main():
tstart = time.time()
tb = pfb_top_block()
tb.run()
tend = time.time()
print("Run time: %f" % (tend - tstart))
if 1:
fig_in = pylab.figure(1, figsize=(16,9), facecolor="w")
fig1 = pylab.figure(2, figsize=(16,9), facecolor="w")
fig2 = pylab.figure(3, figsize=(16,9), facecolor="w")
fig3 = pylab.figure(4, figsize=(16,9), facecolor="w")
Ns = 650
Ne = 20000
fftlen = 8192
winfunc = numpy.blackman
fs = tb._fs
# Plot the input signal on its own figure
d = tb.snk_i.data()[Ns:Ne]
spin_f = fig_in.add_subplot(2, 1, 1)
X,freq = mlab.psd(d, NFFT=fftlen, noverlap=fftlen / 4, Fs=fs,
window = lambda d: d*winfunc(fftlen),
scale_by_freq=True)
X_in = 10.0*numpy.log10(abs(numpy.fft.fftshift(X)))
f_in = numpy.arange(-fs / 2.0, fs / 2.0, fs / float(X_in.size))
pin_f = spin_f.plot(f_in, X_in, "b")
spin_f.set_xlim([min(f_in), max(f_in)+1])
spin_f.set_ylim([-200.0, 50.0])
spin_f.set_title("Input Signal", weight="bold")
spin_f.set_xlabel("Frequency (Hz)")
spin_f.set_ylabel("Power (dBW)")
Ts = 1.0 / fs
Tmax = len(d)*Ts
t_in = numpy.arange(0, Tmax, Ts)
x_in = numpy.array(d)
spin_t = fig_in.add_subplot(2, 1, 2)
pin_t = spin_t.plot(t_in, x_in.real, "b")
pin_t = spin_t.plot(t_in, x_in.imag, "r")
spin_t.set_xlabel("Time (s)")
spin_t.set_ylabel("Amplitude")
Ncols = int(numpy.floor(numpy.sqrt(tb._M)))
Nrows = int(numpy.floor(tb._M / Ncols))
if(tb._M % Ncols != 0):
Nrows += 1
# Plot each of the channels outputs. Frequencies on Figure 2 and
# time signals on Figure 3
fs_o = tb._fs / tb._M
Ts_o = 1.0 / fs_o
Tmax_o = len(d)*Ts_o
for i in range(len(tb.snks)):
# remove issues with the transients at the beginning
# also remove some corruption at the end of the stream
# this is a bug, probably due to the corner cases
d = tb.snks[i].data()[Ns:Ne]
sp1_f = fig1.add_subplot(Nrows, Ncols, 1+i)
X,freq = mlab.psd(d, NFFT=fftlen, noverlap=fftlen / 4, Fs=fs_o,
window = lambda d: d*winfunc(fftlen),
scale_by_freq=True)
X_o = 10.0*numpy.log10(abs(X))
f_o = freq
p2_f = sp1_f.plot(f_o, X_o, "b")
sp1_f.set_xlim([min(f_o), max(f_o)+1])
sp1_f.set_ylim([-200.0, 50.0])
sp1_f.set_title(("Channel %d" % i), weight="bold")
sp1_f.set_xlabel("Frequency (Hz)")
sp1_f.set_ylabel("Power (dBW)")
x_o = numpy.array(d)
t_o = numpy.arange(0, Tmax_o, Ts_o)
sp2_o = fig2.add_subplot(Nrows, Ncols, 1+i)
p2_o = sp2_o.plot(t_o, x_o.real, "b")
p2_o = sp2_o.plot(t_o, x_o.imag, "r")
sp2_o.set_xlim([min(t_o), max(t_o)+1])
sp2_o.set_ylim([-2, 2])
sp2_o.set_title(("Channel %d" % i), weight="bold")
sp2_o.set_xlabel("Time (s)")
sp2_o.set_ylabel("Amplitude")
sp3 = fig3.add_subplot(1,1,1)
p3 = sp3.plot(t_o, x_o.real)
sp3.set_xlim([min(t_o), max(t_o)+1])
sp3.set_ylim([-2, 2])
sp3.set_title("All Channels")
sp3.set_xlabel("Time (s)")
sp3.set_ylabel("Amplitude")
pylab.show()
if __name__ == "__main__":
try:
main()
except KeyboardInterrupt:
pass