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.blksimpl.fm_emph import fm_preemph
26 #from gnuradio import ctcss
28 class nbfm_tx(gr.hier_block):
29 def __init__(self, fg, 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.
37 @param audio_rate: sample rate of audio stream, >= 16k
38 @type audio_rate: integer
39 @param quad_rate: sample rate of output stream
40 @type quad_rate: integer
41 @param tau: preemphasis time constant (default 75e-6)
43 @param max_dev: maximum deviation in Hz (default 5e3)
46 quad_rate must be an integer multiple of audio_rate.
49 # FIXME audio_rate and quad_rate ought to be exact rationals
50 audio_rate = int(audio_rate)
51 quad_rate = int(quad_rate)
53 if quad_rate % audio_rate != 0:
54 raise ValueError, "quad_rate is not an integer multiple of audio_rate"
57 do_interp = audio_rate != quad_rate
60 interp_factor = quad_rate / audio_rate
61 interp_taps = optfir.low_pass (interp_factor, # gain
63 4500, # passband cutoff
64 7000, # stopband cutoff
65 0.1, # passband ripple dB
66 40) # stopband atten dB
68 #print "len(interp_taps) =", len(interp_taps)
69 self.interpolator = gr.interp_fir_filter_fff (interp_factor, interp_taps)
71 self.preemph = fm_preemph (fg, quad_rate, tau=tau)
73 k = 2 * math.pi * max_dev / quad_rate
74 self.modulator = gr.frequency_modulator_fc (k)
77 fg.connect (self.interpolator, self.preemph, self.modulator)
78 gr.hier_block.__init__(self, fg, self.interpolator, self.modulator)
80 fg.connect(self.preemph, self.modulator)
81 gr.hier_block.__init__(self, fg, self.preemph, self.modulator)
84 #class ctcss_gen_f(gr.sig_source_f):
85 # def __init__(self, sample_rate, tone_freq):
86 # gr.sig_source_f.__init__(self, sample_rate, gr.SIN_WAVE, tone_freq, 0.1, 0.0)
88 # def set_tone (self, tone):
89 # gr.sig_source_f.set_frequency(self,tone)
91 class ctcss_gen_f(gr.hier_block):
92 def __init__(self, fg, sample_rate, tone_freq):
93 self.plgen = gr.sig_source_f(sample_rate, gr.GR_SIN_WAVE, tone_freq, 0.1, 0.0)
95 gr.hier_block.__init__(self, fg, self.plgen, self.plgen)