1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
|
#!/usr/bin/env python
#
# Copyright 2009 Free Software Foundation, Inc.
#
# This file is part of GNU Radio
#
# GNU Radio is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3, or (at your option)
# any later version.
#
# GNU Radio is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with GNU Radio; see the file COPYING. If not, write to
# the Free Software Foundation, Inc., 51 Franklin Street,
# Boston, MA 02110-1301, USA.
#
from gnuradio import gr, blks2
import os
import scipy, pylab
from scipy import fftpack
from pylab import mlab
import time
#print os.getpid()
#raw_input()
class pfb_top_block(gr.top_block):
def __init__(self):
gr.top_block.__init__(self)
self._N = 10000000 # number of samples to use
self._fs = 10000 # initial sampling rate
self._decim = 20 # Decimation rate
# Generate the prototype filter taps for the decimators with a 200 Hz bandwidth
self._taps = gr.firdes.low_pass_2(1, self._fs, 200, 150,
attenuation_dB=120, window=gr.firdes.WIN_BLACKMAN_hARRIS)
# Calculate the number of taps per channel for our own information
tpc = scipy.ceil(float(len(self._taps)) / float(self._decim))
print "Number of taps: ", len(self._taps)
print "Number of filters: ", self._decim
print "Taps per channel: ", tpc
# Build the input signal source
# We create a list of freqs, and a sine wave is generated and added to the source
# for each one of these frequencies.
self.signals = list()
self.add = gr.add_cc()
freqs = [10, 20, 2040]
for i in xrange(len(freqs)):
self.signals.append(gr.sig_source_c(self._fs, gr.GR_SIN_WAVE, freqs[i], 1))
self.connect(self.signals[i], (self.add,i))
self.head = gr.head(gr.sizeof_gr_complex, self._N)
# Construct a PFB decimator filter
self.pfb = blks2.pfb_decimator_ccf(self._decim, self._taps, 0)
# Construct a standard FIR decimating filter
self.dec = gr.fir_filter_ccf(self._decim, self._taps)
self.snk_i = gr.vector_sink_c()
# Connect the blocks
self.connect(self.add, self.head, self.pfb)
self.connect(self.add, self.snk_i)
# Create the sink for the decimated siganl
self.snk = gr.vector_sink_c()
self.connect(self.pfb, self.snk)
def main():
tb = pfb_top_block()
tstart = time.time()
tb.run()
tend = time.time()
print "Run time: %f" % (tend - tstart)
if 1:
fig1 = pylab.figure(1, figsize=(16,9))
fig2 = pylab.figure(2, figsize=(16,9))
Ns = 10000
Ne = 10000
fftlen = 8192
winfunc = scipy.blackman
fs = tb._fs
# Plot the input to the decimator
d = tb.snk_i.data()[Ns:Ns+Ne]
sp1_f = fig1.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*scipy.log10(abs(fftpack.fftshift(X)))
f_in = scipy.arange(-fs/2.0, fs/2.0, fs/float(X_in.size))
p1_f = sp1_f.plot(f_in, X_in, "b")
sp1_f.set_xlim([min(f_in), max(f_in)+1])
sp1_f.set_ylim([-200.0, 50.0])
sp1_f.set_title("Input Signal", weight="bold")
sp1_f.set_xlabel("Frequency (Hz)")
sp1_f.set_ylabel("Power (dBW)")
Ts = 1.0/fs
Tmax = len(d)*Ts
t_in = scipy.arange(0, Tmax, Ts)
x_in = scipy.array(d)
sp1_t = fig1.add_subplot(2, 1, 2)
p1_t = sp1_t.plot(t_in, x_in.real, "b")
p1_t = sp1_t.plot(t_in, x_in.imag, "r")
sp1_t.set_ylim([-tb._decim*1.1, tb._decim*1.1])
sp1_t.set_xlabel("Time (s)")
sp1_t.set_ylabel("Amplitude")
# Plot the output of the decimator
fs_o = tb._fs / tb._decim
sp2_f = fig2.add_subplot(2, 1, 1)
d = tb.snk.data()[Ns:Ns+Ne]
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*scipy.log10(abs(fftpack.fftshift(X)))
f_o = scipy.arange(-fs_o/2.0, fs_o/2.0, fs_o/float(X_o.size))
p2_f = sp2_f.plot(f_o, X_o, "b")
sp2_f.set_xlim([min(f_o), max(f_o)+1])
sp2_f.set_ylim([-200.0, 50.0])
sp2_f.set_title("PFB Decimated Signal", weight="bold")
sp2_f.set_xlabel("Frequency (Hz)")
sp2_f.set_ylabel("Power (dBW)")
Ts_o = 1.0/fs_o
Tmax_o = len(d)*Ts_o
x_o = scipy.array(d)
t_o = scipy.arange(0, Tmax_o, Ts_o)
sp2_t = fig2.add_subplot(2, 1, 2)
p2_t = sp2_t.plot(t_o, x_o.real, "b-o")
p2_t = sp2_t.plot(t_o, x_o.imag, "r-o")
sp2_t.set_ylim([-2.5, 2.5])
sp2_t.set_xlabel("Time (s)")
sp2_t.set_ylabel("Amplitude")
pylab.show()
if __name__ == "__main__":
try:
main()
except KeyboardInterrupt:
pass
|
