2 # Copyright 2005 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.
23 from gnuradio import gr, optfir
24 from gnuradio.blks2impl.fm_emph import fm_preemph
26 #from gnuradio import ctcss
28 class nbfm_tx(gr.hier_block2):
29 def __init__(self, audio_rate, quad_rate, tau=75e-6, max_dev=5e3):
31 Narrow Band FM Transmitter.
33 Takes a single float input stream of audio samples in the range [-1,+1]
34 and produces a single FM modulated complex baseband output.
36 @param audio_rate: sample rate of audio stream, >= 16k
37 @type audio_rate: integer
38 @param quad_rate: sample rate of output stream
39 @type quad_rate: integer
40 @param tau: preemphasis time constant (default 75e-6)
42 @param max_dev: maximum deviation in Hz (default 5e3)
45 quad_rate must be an integer multiple of audio_rate.
48 gr.hier_block2.__init__(self, "nbfm_tx",
49 gr.io_signature(1, 1, gr.sizeof_float), # Input signature
50 gr.io_signature(1, 1, gr.sizeof_gr_complex)) # Output signature
52 # FIXME audio_rate and quad_rate ought to be exact rationals
53 audio_rate = int(audio_rate)
54 quad_rate = int(quad_rate)
56 if quad_rate % audio_rate != 0:
57 raise ValueError, "quad_rate is not an integer multiple of audio_rate"
60 do_interp = audio_rate != quad_rate
63 interp_factor = quad_rate / audio_rate
64 interp_taps = optfir.low_pass (interp_factor, # gain
66 4500, # passband cutoff
67 7000, # stopband cutoff
68 0.1, # passband ripple dB
69 40) # stopband atten dB
71 #print "len(interp_taps) =", len(interp_taps)
72 self.interpolator = gr.interp_fir_filter_fff (interp_factor, interp_taps)
74 self.preemph = fm_preemph (quad_rate, tau=tau)
76 k = 2 * math.pi * max_dev / quad_rate
77 self.modulator = gr.frequency_modulator_fc (k)
80 self.connect (self, self.interpolator, self.preemph, self.modulator, self)
82 self.connect(self, self.preemph, self.modulator, self)
85 class ctcss_gen_f(gr.hier_block2):
86 def __init__(self, sample_rate, tone_freq):
87 gr.hier_block2.__init__(self, "ctcss_gen_f",
88 gr.io_signature(0, 0, 0), # Input signature
89 gr.io_signature(1, 1, gr.sizeof_float)) # Output signature
91 self.plgen = gr.sig_source_f(sample_rate, gr.GR_SIN_WAVE, tone_freq, 0.1, 0.0)
92 self.connect(self.plgen, self)