def __init__(self,
mode,
deviation=75000,
demod_rate=48000,
band_filter=None,
band_filter_transition=None,
tau=75e-6,
no_audio_filter=False, # TODO kludge to support APRS demod looking for tones
**kwargs):
SimpleAudioDemodulator.__init__(self,
mode=mode,
demod_rate=demod_rate,
band_filter=band_filter,
band_filter_transition=band_filter_transition,
**kwargs)
self.__no_audio_filter = no_audio_filter
self.__qdemod = analog.quadrature_demod_cf(demod_rate / (TWO_PI * deviation))
if tau > 0.0:
self.__deemph = fm_emph.fm_deemph(demod_rate, tau)
else:
self.__deemph = None
self.do_connect()
def __init__(
self,
mode,
deviation=75000,
demod_rate=48000,
band_filter=None,
band_filter_transition=None,
tau=75e-6,
no_audio_filter=False, # TODO kludge to support APRS demod looking for tones
**kwargs):
SimpleAudioDemodulator.__init__(
self,
mode=mode,
demod_rate=demod_rate,
band_filter=band_filter,
band_filter_transition=band_filter_transition,
**kwargs)
self.__no_audio_filter = no_audio_filter
self.__qdemod = analog.quadrature_demod_cf(demod_rate /
(TWO_PI * deviation))
if tau > 0.0:
self.__deemph = fm_emph.fm_deemph(demod_rate, tau)
else:
self.__deemph = None
self.do_connect()
def __init__(self, rate, decim, gate=False):
gr.hier_block2.__init__(self, "fm_demod",
gr.io_signature(1, 1, gr.sizeof_gr_complex),
gr.io_signature(1, 1, gr.sizeof_float))
tau = 75.e-6
deviation = 5.e3
k = rate / (2 * pi * deviation)
self.rate = rate
self.quad = analog.quadrature_demod_cf(k)
self.squelch = scanner.standard_squelch_ff(gate=gate)
self.deemph = fm_deemph(rate, tau)
self.nfilts = 32
audio_taps = optfir.band_pass(self.nfilts, self.rate * self.nfilts,
250, 300, 3000, 4000, 0.2, 40)
self.resamp = pfb.arb_resampler_fff(1. / decim, audio_taps)
self.connect(self, self.quad, self.squelch, self.deemph, self.resamp,
self)
def __init__(self, rate, decim, gate=False):
gr.hier_block2.__init__(self,
"fm_demod",
gr.io_signature(1,1,gr.sizeof_gr_complex),
gr.io_signature(1,1,gr.sizeof_float))
tau=75.e-6
deviation = 5.e3
k=rate/(2*pi*deviation)
self.rate = rate
self.quad = analog.quadrature_demod_cf(k)
self.squelch = scanner.standard_squelch_ff(gate=gate)
self.deemph = fm_deemph(rate, tau)
self.nfilts = 32
audio_taps = optfir.band_pass(self.nfilts,
self.rate*self.nfilts,
250,
300,
3000,
4000,
0.2,
40)
self.resamp = pfb.arb_resampler_fff(1./decim, audio_taps)
self.connect(self, self.quad, self.squelch, self.deemph, self.resamp, self)
def connect_audio_stage(self, input_port):
stereo_rate = self.demod_rate
normalizer = TWO_PI / stereo_rate
pilot_tone = 19000
pilot_low = pilot_tone * 0.98
pilot_high = pilot_tone * 1.02
def make_audio_filter():
return grfilter.fir_filter_fff(
stereo_rate // self.__audio_int_rate, # decimation
firdes.low_pass(
1.0,
stereo_rate,
15000,
5000,
firdes.WIN_HAMMING))
stereo_pilot_filter = grfilter.fir_filter_fcc(
1, # decimation
firdes.complex_band_pass(
1.0,
stereo_rate,
pilot_low,
pilot_high,
300)) # TODO magic number from gqrx
stereo_pilot_pll = analog.pll_refout_cc(
loop_bw=0.001,
max_freq=normalizer * pilot_high,
min_freq=normalizer * pilot_low)
stereo_pilot_doubler = blocks.multiply_cc()
stereo_pilot_out = blocks.complex_to_real()
difference_channel_mixer = blocks.multiply_ff()
difference_channel_filter = make_audio_filter()
mono_channel_filter = make_audio_filter()
mixL = blocks.add_ff(1)
mixR = blocks.sub_ff(1)
# connections
self.connect(input_port, mono_channel_filter)
if self.__decode_stereo:
# stereo pilot tone tracker
self.connect(
input_port,
stereo_pilot_filter,
stereo_pilot_pll)
self.connect(stereo_pilot_pll, (stereo_pilot_doubler, 0))
self.connect(stereo_pilot_pll, (stereo_pilot_doubler, 1))
self.connect(stereo_pilot_doubler, stereo_pilot_out)
# pick out stereo left-right difference channel (at stereo_rate)
self.connect(input_port, (difference_channel_mixer, 0))
self.connect(stereo_pilot_out, (difference_channel_mixer, 1))
self.connect(
difference_channel_mixer,
blocks.multiply_const_ff(6), # TODO: Completely empirical fudge factor. This should not be necessary. I believe this is at least partly due to phase error in the pilot signal.
difference_channel_filter)
# recover left/right channels (at self.__audio_int_rate)
self.connect(difference_channel_filter, (mixL, 1))
self.connect(difference_channel_filter, (mixR, 1))
self.connect(mono_channel_filter, (mixL, 0))
self.connect(mono_channel_filter, (mixR, 0))
resamplerL = self._make_resampler((mixL, 0), self.__audio_int_rate)
resamplerR = self._make_resampler((mixR, 0), self.__audio_int_rate)
deemphL = fm_emph.fm_deemph(self.__audio_int_rate, 75e-6)
deemphR = fm_emph.fm_deemph(self.__audio_int_rate, 75e-6)
self.connect(resamplerL, deemphL)
self.connect(resamplerR, deemphR)
self.connect_audio_output(deemphL, deemphR)
else:
resampler = self._make_resampler(mono_channel_filter, self.__audio_int_rate)
deemph = fm_emph.fm_deemph(self.__audio_int_rate, 75e-6)
self.connect(resampler, deemph)
self.connect_audio_output(deemph, deemph)
def connect_audio_stage(self, input_port):
stereo_rate = self.demod_rate
normalizer = TWO_PI / stereo_rate
pilot_tone = 19000
pilot_low = pilot_tone * 0.98
pilot_high = pilot_tone * 1.02
def make_audio_filter():
return grfilter.fir_filter_fff(
stereo_rate // self.__audio_int_rate, # decimation
firdes.low_pass(1.0, stereo_rate, 15000, 5000,
firdes.WIN_HAMMING))
stereo_pilot_filter = grfilter.fir_filter_fcc(
1, # decimation
firdes.complex_band_pass(1.0, stereo_rate, pilot_low, pilot_high,
300)) # TODO magic number from gqrx
stereo_pilot_pll = analog.pll_refout_cc(
loop_bw=0.001,
max_freq=normalizer * pilot_high,
min_freq=normalizer * pilot_low)
stereo_pilot_doubler = blocks.multiply_cc()
stereo_pilot_out = blocks.complex_to_real()
difference_channel_mixer = blocks.multiply_ff()
difference_channel_filter = make_audio_filter()
mono_channel_filter = make_audio_filter()
mixL = blocks.add_ff(1)
mixR = blocks.sub_ff(1)
# connections
self.connect(input_port, mono_channel_filter)
if self.__decode_stereo:
# stereo pilot tone tracker
self.connect(input_port, stereo_pilot_filter, stereo_pilot_pll)
self.connect(stereo_pilot_pll, (stereo_pilot_doubler, 0))
self.connect(stereo_pilot_pll, (stereo_pilot_doubler, 1))
self.connect(stereo_pilot_doubler, stereo_pilot_out)
# pick out stereo left-right difference channel (at stereo_rate)
self.connect(input_port, (difference_channel_mixer, 0))
self.connect(stereo_pilot_out, (difference_channel_mixer, 1))
self.connect(
difference_channel_mixer,
blocks.multiply_const_ff(
6
), # TODO: Completely empirical fudge factor. This should not be necessary. I believe this is at least partly due to phase error in the pilot signal.
difference_channel_filter)
# recover left/right channels (at self.__audio_int_rate)
self.connect(difference_channel_filter, (mixL, 1))
self.connect(difference_channel_filter, (mixR, 1))
self.connect(mono_channel_filter, (mixL, 0))
self.connect(mono_channel_filter, (mixR, 0))
resamplerL = self._make_resampler((mixL, 0), self.__audio_int_rate)
resamplerR = self._make_resampler((mixR, 0), self.__audio_int_rate)
deemphL = fm_emph.fm_deemph(self.__audio_int_rate, 75e-6)
deemphR = fm_emph.fm_deemph(self.__audio_int_rate, 75e-6)
self.connect(resamplerL, deemphL)
self.connect(resamplerR, deemphR)
self.connect_audio_output(deemphL, deemphR)
else:
resampler = self._make_resampler(mono_channel_filter,
self.__audio_int_rate)
deemph = fm_emph.fm_deemph(self.__audio_int_rate, 75e-6)
self.connect(resampler, deemph)
self.connect_audio_output(deemph, deemph)
