2 # Copyright 2008 Free Software Foundation, Inc.
4 # This file is part of GNU Radio
6 # GNU Radio is free software; you can redistribute it and/or modify
7 # it under the terms of the GNU General Public License as published by
8 # the Free Software Foundation; either version 3, or (at your option)
11 # GNU Radio is distributed in the hope that it will be useful,
12 # but WITHOUT ANY WARRANTY; without even the implied warranty of
13 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 # GNU General Public License for more details.
16 # You should have received a copy of the GNU General Public License
17 # along with GNU Radio; see the file COPYING. If not, write to
18 # the Free Software Foundation, Inc., 51 Franklin Street,
19 # Boston, MA 02110-1301, USA.
22 from gnuradio import gr, window
23 from stream_to_vector_decimator import stream_to_vector_decimator
26 class _logpwrfft_base(gr.hier_block2):
28 Create a log10(abs(fft)) stream chain, with real or complex input.
31 def __init__(self, sample_rate, fft_size, ref_scale, frame_rate, avg_alpha, average):
33 Create an log10(abs(fft)) stream chain.
34 Provide access to the setting the filter and sample rate.
35 @param sample_rate Incoming stream sample rate
36 @param fft_size Number of FFT bins
37 @param ref_scale Sets 0 dB value input amplitude
38 @param frame_rate Output frame rate
39 @param avg_alpha FFT averaging (over time) constant [0.0-1.0]
40 @param average Whether to average [True, False]
42 gr.hier_block2.__init__(self, self._name,
43 gr.io_signature(1, 1, self._item_size), # Input signature
44 gr.io_signature(1, 1, gr.sizeof_float*fft_size)) # Output signature
46 self._sd = stream_to_vector_decimator(item_size=self._item_size,
47 sample_rate=sample_rate,
51 fft_window = window.blackmanharris(fft_size)
52 fft = self._fft_block[0](fft_size, True, fft_window)
53 window_power = sum(map(lambda x: x*x, fft_window))
55 c2mag = gr.complex_to_mag(fft_size)
56 self._avg = gr.single_pole_iir_filter_ff(1.0, fft_size)
57 self._log = gr.nlog10_ff(20, fft_size,
58 -10*math.log10(fft_size) # Adjust for number of bins
59 -10*math.log10(window_power/fft_size) # Adjust for windowing loss
60 -20*math.log10(ref_scale/2)) # Adjust for reference scale
61 self.connect(self, self._sd, fft, c2mag, self._avg, self._log, self)
62 self.set_average(average)
63 self.set_avg_alpha(avg_alpha)
65 def set_sample_rate(self, sample_rate):
67 Set the new sampling rate
68 @param sample_rate the new rate
70 self._sd.set_sample_rate(sample_rate)
72 def set_average(self, average):
74 Set the averaging filter on/off.
75 @param average true to set averaging on
77 self._average = average
79 self._avg.set_taps(self._avg_alpha)
81 self._avg.set_taps(1.0)
83 def set_avg_alpha(self, avg_alpha):
85 Set the average alpha and set the taps if average was on.
86 @param avg_alpha the new iir filter tap
88 self._avg_alpha = avg_alpha
89 self.set_average(self._average)
92 class logpwrfft_f(_logpwrfft_base):
94 Create an fft block chain, with real input.
97 _item_size = gr.sizeof_float
98 _fft_block = (gr.fft_vfc, )
100 class logpwrfft_c(_logpwrfft_base):
102 Create an fft block chain, with complex input.
104 _name = "logpwrfft_c"
105 _item_size = gr.sizeof_gr_complex
106 _fft_block = (gr.fft_vcc, )