def __init__(self):
gr.top_block.__init__(self)
##################################################
# Variables
##################################################
self.signal_freq = signal_freq = 5000
self.samp_rate = samp_rate = 48000
self.bw = bw = 200
##################################################
# Blocks
##################################################
self.gr_probe_ref = gr.probe_signal_f()
self.gr_probe_mag = gr.probe_signal_f()
self.gr_probe_arg = gr.probe_signal_f()
self.gr_nlog10_ff_ref = gr.nlog10_ff(1, 1, 0)
self.gr_nlog10_ff_0 = gr.nlog10_ff(1, 1, 0)
self.gr_divide_xx_0 = gr.divide_cc(1)
self.gr_complex_to_mag_ref = gr.complex_to_mag(1)
self.gr_complex_to_mag_0 = gr.complex_to_mag(1)
self.gr_complex_to_arg_0 = gr.complex_to_arg(1)
self.band_pass_filter_0_0 = gr.fir_filter_fcc(
1,
firdes.complex_band_pass(
1, samp_rate, signal_freq - bw / 2, signal_freq + bw / 2, 100, firdes.WIN_BLACKMAN, 6.76
),
)
self.band_pass_filter_0 = gr.fir_filter_fcc(
1,
firdes.complex_band_pass(
1, samp_rate, signal_freq - bw / 2, signal_freq + bw / 2, 100, firdes.WIN_BLACKMAN, 6.76
),
)
self.audio_source_0 = audio.source(samp_rate, "", True)
##################################################
# Connections
##################################################
self.connect((self.band_pass_filter_0_0, 0), (self.gr_complex_to_mag_0, 0))
self.connect((self.gr_complex_to_mag_0, 0), (self.gr_nlog10_ff_0, 0))
self.connect((self.gr_divide_xx_0, 0), (self.gr_complex_to_arg_0, 0))
self.connect((self.band_pass_filter_0_0, 0), (self.gr_divide_xx_0, 0))
self.connect((self.band_pass_filter_0, 0), (self.gr_divide_xx_0, 1))
self.connect((self.audio_source_0, 1), (self.band_pass_filter_0_0, 0))
self.connect((self.audio_source_0, 0), (self.band_pass_filter_0, 0))
self.connect((self.gr_nlog10_ff_0, 0), (self.gr_probe_mag, 0))
self.connect((self.gr_complex_to_arg_0, 0), (self.gr_probe_arg, 0))
self.connect((self.band_pass_filter_0, 0), (self.gr_complex_to_mag_ref, 0))
self.connect((self.gr_complex_to_mag_ref, 0), (self.gr_nlog10_ff_ref, 0))
self.connect((self.gr_nlog10_ff_ref, 0), (self.gr_probe_ref, 0))
def __init__(self, demod_rate, audio_decimation):
"""
Hierarchical block for demodulating a broadcast FM signal.
The input is the downconverted complex baseband signal
(gr_complex). The output is two streams of the demodulated
audio (float) 0=Left, 1=Right.
@param demod_rate: input sample rate of complex baseband input.
@type demod_rate: float
@param audio_decimation: how much to decimate demod_rate to get to audio.
@type audio_decimation: integer
"""
gr.hier_block2.__init__(
self,
"wfm_rcv_fmdet",
gr.io_signature(1, 1, gr.sizeof_gr_complex), # Input signature
gr.io_signature(2, 2, gr.sizeof_float)) # Output signature
lowfreq = -125e3 / demod_rate
highfreq = 125e3 / demod_rate
audio_rate = demod_rate / audio_decimation
# We assign to self so that outsiders can grab the demodulator
# if they need to. E.g., to plot its output.
#
# input: complex; output: float
self.fm_demod = gr.fmdet_cf(demod_rate, lowfreq, highfreq, 0.05)
# input: float; output: float
self.deemph_Left = fm_deemph(audio_rate)
self.deemph_Right = fm_deemph(audio_rate)
# compute FIR filter taps for audio filter
width_of_transition_band = audio_rate / 32
audio_coeffs = gr.firdes.low_pass(
1.0, # gain
demod_rate, # sampling rate
15000,
width_of_transition_band,
gr.firdes.WIN_HAMMING)
# input: float; output: float
self.audio_filter = gr.fir_filter_fff(audio_decimation, audio_coeffs)
if 1:
# Pick off the stereo carrier/2 with this filter. It
# attenuated 10 dB so apply 10 dB gain We pick off the
# negative frequency half because we want to base band by
# it!
## NOTE THIS WAS HACKED TO OFFSET INSERTION LOSS DUE TO
## DEEMPHASIS
stereo_carrier_filter_coeffs = gr.firdes.complex_band_pass(
10.0, demod_rate, -19020, -18980, width_of_transition_band,
gr.firdes.WIN_HAMMING)
#print "len stereo carrier filter = ",len(stereo_carrier_filter_coeffs)
#print "stereo carrier filter ", stereo_carrier_filter_coeffs
#print "width of transition band = ",width_of_transition_band, " audio rate = ", audio_rate
# Pick off the double side band suppressed carrier
# Left-Right audio. It is attenuated 10 dB so apply 10 dB
# gain
stereo_dsbsc_filter_coeffs = gr.firdes.complex_band_pass(
20.0, demod_rate, 38000 - 15000 / 2, 38000 + 15000 / 2,
width_of_transition_band, gr.firdes.WIN_HAMMING)
#print "len stereo dsbsc filter = ",len(stereo_dsbsc_filter_coeffs)
#print "stereo dsbsc filter ", stereo_dsbsc_filter_coeffs
# construct overlap add filter system from coefficients
# for stereo carrier
self.stereo_carrier_filter = gr.fir_filter_fcc(
audio_decimation, stereo_carrier_filter_coeffs)
# carrier is twice the picked off carrier so arrange to do
# a commplex multiply
self.stereo_carrier_generator = gr.multiply_cc()
# Pick off the rds signal
stereo_rds_filter_coeffs = gr.firdes.complex_band_pass(
30.0, demod_rate, 57000 - 1500, 57000 + 1500,
width_of_transition_band, gr.firdes.WIN_HAMMING)
#print "len stereo dsbsc filter = ",len(stereo_dsbsc_filter_coeffs)
#print "stereo dsbsc filter ", stereo_dsbsc_filter_coeffs
# construct overlap add filter system from coefficients for stereo carrier
self.rds_signal_filter = gr.fir_filter_fcc(
audio_decimation, stereo_rds_filter_coeffs)
self.rds_carrier_generator = gr.multiply_cc()
self.rds_signal_generator = gr.multiply_cc()
self_rds_signal_processor = gr.null_sink(gr.sizeof_gr_complex)
loop_bw = 2 * math.pi / 100.0
max_freq = -2.0 * math.pi * 18990 / audio_rate
min_freq = -2.0 * math.pi * 19010 / audio_rate
self.stereo_carrier_pll_recovery = gr.pll_refout_cc(
loop_bw, max_freq, min_freq)
#self.stereo_carrier_pll_recovery.squelch_enable(False)
##pll_refout does not have squelch yet, so disabled for
#now
# set up mixer (multiplier) to get the L-R signal at
# baseband
self.stereo_basebander = gr.multiply_cc()
# pick off the real component of the basebanded L-R
# signal. The imaginary SHOULD be zero
self.LmR_real = gr.complex_to_real()
self.Make_Left = gr.add_ff()
self.Make_Right = gr.sub_ff()
self.stereo_dsbsc_filter = gr.fir_filter_fcc(
audio_decimation, stereo_dsbsc_filter_coeffs)
if 1:
# send the real signal to complex filter to pick off the
# carrier and then to one side of a multiplier
self.connect(self, self.fm_demod, self.stereo_carrier_filter,
self.stereo_carrier_pll_recovery,
(self.stereo_carrier_generator, 0))
# send the already filtered carrier to the otherside of the carrier
# the resulting signal from this multiplier is the carrier
# with correct phase but at -38000 Hz.
self.connect(self.stereo_carrier_pll_recovery,
(self.stereo_carrier_generator, 1))
# send the new carrier to one side of the mixer (multiplier)
self.connect(self.stereo_carrier_generator,
(self.stereo_basebander, 0))
# send the demphasized audio to the DSBSC pick off filter, the complex
# DSBSC signal at +38000 Hz is sent to the other side of the mixer/multiplier
# the result is BASEBANDED DSBSC with phase zero!
self.connect(self.fm_demod, self.stereo_dsbsc_filter,
(self.stereo_basebander, 1))
# Pick off the real part since the imaginary is
# theoretically zero and then to one side of a summer
self.connect(self.stereo_basebander, self.LmR_real,
(self.Make_Left, 0))
#take the same real part of the DSBSC baseband signal and
#send it to negative side of a subtracter
self.connect(self.LmR_real, (self.Make_Right, 1))
# Make rds carrier by taking the squared pilot tone and
# multiplying by pilot tone
self.connect(self.stereo_basebander,
(self.rds_carrier_generator, 0))
self.connect(self.stereo_carrier_pll_recovery,
(self.rds_carrier_generator, 1))
# take signal, filter off rds, send into mixer 0 channel
self.connect(self.fm_demod, self.rds_signal_filter,
(self.rds_signal_generator, 0))
# take rds_carrier_generator output and send into mixer 1
# channel
self.connect(self.rds_carrier_generator,
(self.rds_signal_generator, 1))
# send basebanded rds signal and send into "processor"
# which for now is a null sink
self.connect(self.rds_signal_generator, self_rds_signal_processor)
if 1:
# pick off the audio, L+R that is what we used to have and
# send it to the summer
self.connect(self.fm_demod, self.audio_filter, (self.Make_Left, 1))
# take the picked off L+R audio and send it to the PLUS
# side of the subtractor
self.connect(self.audio_filter, (self.Make_Right, 0))
# The result of Make_Left gets (L+R) + (L-R) and results in 2*L
# The result of Make_Right gets (L+R) - (L-R) and results in 2*R
self.connect(self.Make_Left, self.deemph_Left, (self, 0))
self.connect(self.Make_Right, self.deemph_Right, (self, 1))
def __init__ (self, fg, demod_rate, audio_decimation):
"""
Hierarchical block for demodulating a broadcast FM signal.
The input is the downconverted complex baseband signal (gr_complex).
The output is two streams of the demodulated audio (float) 0=Left, 1=Right.
@param fg: flow graph.
@type fg: flow graph
@param demod_rate: input sample rate of complex baseband input.
@type demod_rate: float
@param audio_decimation: how much to decimate demod_rate to get to audio.
@type audio_decimation: integer
"""
bandwidth = 200e3
audio_rate = demod_rate / audio_decimation
# We assign to self so that outsiders can grab the demodulator
# if they need to. E.g., to plot its output.
#
# input: complex; output: float
alpha = 0.25*bandwidth * math.pi / demod_rate
beta = alpha * alpha / 4.0
max_freq = 2.0*math.pi*100e3/demod_rate
self.fm_demod = gr.pll_freqdet_cf (alpha,beta,max_freq,-max_freq)
# input: float; output: float
self.deemph_Left = fm_deemph (fg, audio_rate)
self.deemph_Right = fm_deemph (fg, audio_rate)
# compute FIR filter taps for audio filter
width_of_transition_band = audio_rate / 32
audio_coeffs = gr.firdes.low_pass (1.0 , # gain
demod_rate, # sampling rate
15000 ,
width_of_transition_band,
gr.firdes.WIN_HAMMING)
# input: float; output: float
self.audio_filter = gr.fir_filter_fff (audio_decimation, audio_coeffs)
if 1:
# Pick off the stereo carrier/2 with this filter. It attenuated 10 dB so apply 10 dB gain
# We pick off the negative frequency half because we want to base band by it!
## NOTE THIS WAS HACKED TO OFFSET INSERTION LOSS DUE TO DEEMPHASIS
stereo_carrier_filter_coeffs = gr.firdes.complex_band_pass(10.0,
demod_rate,
-19020,
-18980,
width_of_transition_band,
gr.firdes.WIN_HAMMING)
#print "len stereo carrier filter = ",len(stereo_carrier_filter_coeffs)
#print "stereo carrier filter ", stereo_carrier_filter_coeffs
#print "width of transition band = ",width_of_transition_band, " audio rate = ", audio_rate
# Pick off the double side band suppressed carrier Left-Right audio. It is attenuated 10 dB so apply 10 dB gain
stereo_dsbsc_filter_coeffs = gr.firdes.complex_band_pass(20.0,
demod_rate,
38000-15000/2,
38000+15000/2,
width_of_transition_band,
gr.firdes.WIN_HAMMING)
#print "len stereo dsbsc filter = ",len(stereo_dsbsc_filter_coeffs)
#print "stereo dsbsc filter ", stereo_dsbsc_filter_coeffs
# construct overlap add filter system from coefficients for stereo carrier
self.stereo_carrier_filter = gr.fir_filter_fcc(audio_decimation, stereo_carrier_filter_coeffs)
# carrier is twice the picked off carrier so arrange to do a commplex multiply
self.stereo_carrier_generator = gr.multiply_cc();
# Pick off the rds signal
stereo_rds_filter_coeffs = gr.firdes.complex_band_pass(30.0,
demod_rate,
57000 - 1500,
57000 + 1500,
width_of_transition_band,
gr.firdes.WIN_HAMMING)
#print "len stereo dsbsc filter = ",len(stereo_dsbsc_filter_coeffs)
#print "stereo dsbsc filter ", stereo_dsbsc_filter_coeffs
# construct overlap add filter system from coefficients for stereo carrier
self.stereo_carrier_filter = gr.fir_filter_fcc(audio_decimation, stereo_carrier_filter_coeffs)
self.rds_signal_filter = gr.fir_filter_fcc(audio_decimation, stereo_rds_filter_coeffs)
self.rds_carrier_generator = gr.multiply_cc();
self.rds_signal_generator = gr.multiply_cc();
self_rds_signal_processor = gr.null_sink(gr.sizeof_gr_complex);
alpha = 5 * 0.25 * math.pi / (audio_rate)
beta = alpha * alpha / 4.0
max_freq = -2.0*math.pi*18990/audio_rate;
min_freq = -2.0*math.pi*19010/audio_rate;
self.stereo_carrier_pll_recovery = gr.pll_refout_cc(alpha,beta,max_freq,min_freq);
#self.stereo_carrier_pll_recovery.squelch_enable(False) #pll_refout does not have squelch yet, so disabled for now
# set up mixer (multiplier) to get the L-R signal at baseband
self.stereo_basebander = gr.multiply_cc();
# pick off the real component of the basebanded L-R signal. The imaginary SHOULD be zero
self.LmR_real = gr.complex_to_real();
self.Make_Left = gr.add_ff();
self.Make_Right = gr.sub_ff();
self.stereo_dsbsc_filter = gr.fir_filter_fcc(audio_decimation, stereo_dsbsc_filter_coeffs)
if 1:
# send the real signal to complex filter to pick off the carrier and then to one side of a multiplier
fg.connect (self.fm_demod,self.stereo_carrier_filter,self.stereo_carrier_pll_recovery, (self.stereo_carrier_generator,0))
# send the already filtered carrier to the otherside of the carrier
fg.connect (self.stereo_carrier_pll_recovery, (self.stereo_carrier_generator,1))
# the resulting signal from this multiplier is the carrier with correct phase but at -38000 Hz.
# send the new carrier to one side of the mixer (multiplier)
fg.connect (self.stereo_carrier_generator, (self.stereo_basebander,0))
# send the demphasized audio to the DSBSC pick off filter, the complex
# DSBSC signal at +38000 Hz is sent to the other side of the mixer/multiplier
fg.connect (self.fm_demod,self.stereo_dsbsc_filter, (self.stereo_basebander,1))
# the result is BASEBANDED DSBSC with phase zero!
# Pick off the real part since the imaginary is theoretically zero and then to one side of a summer
fg.connect (self.stereo_basebander, self.LmR_real, (self.Make_Left,0))
#take the same real part of the DSBSC baseband signal and send it to negative side of a subtracter
fg.connect (self.LmR_real,(self.Make_Right,1))
# Make rds carrier by taking the squared pilot tone and multiplying by pilot tone
fg.connect (self.stereo_basebander,(self.rds_carrier_generator,0))
fg.connect (self.stereo_carrier_pll_recovery,(self.rds_carrier_generator,1))
# take signal, filter off rds, send into mixer 0 channel
fg.connect (self.fm_demod,self.rds_signal_filter,(self.rds_signal_generator,0))
# take rds_carrier_generator output and send into mixer 1 channel
fg.connect (self.rds_carrier_generator,(self.rds_signal_generator,1))
# send basebanded rds signal and send into "processor" which for now is a null sink
fg.connect (self.rds_signal_generator,self_rds_signal_processor)
if 1:
# pick off the audio, L+R that is what we used to have and send it to the summer
fg.connect(self.fm_demod, self.audio_filter, (self.Make_Left, 1))
# take the picked off L+R audio and send it to the PLUS side of the subtractor
fg.connect(self.audio_filter,(self.Make_Right, 0))
# The result of Make_Left gets (L+R) + (L-R) and results in 2*L
# The result of Make_Right gets (L+R) - (L-R) and results in 2*R
# kludge the signals into a stereo channel
kludge = gr.kludge_copy(gr.sizeof_float)
fg.connect(self.Make_Left , self.deemph_Left, (kludge, 0))
fg.connect(self.Make_Right, self.deemph_Right, (kludge, 1))
#send it to the audio system
gr.hier_block.__init__(self,
fg,
self.fm_demod, # head of the pipeline
kludge) # tail of the pipeline
else:
fg.connect (self.fm_demod, self.audio_filter)
gr.hier_block.__init__(self,
fg,
self.fm_demod, # head of the pipeline
self.audio_filter) # tail of the pipeline
def __init__(self): grc_wxgui.top_block_gui.__init__(self, title="Audio Fft 2") ################################################## # Variables ################################################## self.samp_rate = samp_rate = 48000 ################################################## # Blocks ################################################## self.wxgui_numbersink2_0_0 = numbersink2.number_sink_f( self.GetWin(), unit="deg", minval=-90, maxval=90, factor=90/3.14159, decimal_places=10, ref_level=0, sample_rate=samp_rate, number_rate=15, average=False, avg_alpha=None, label="Angle", peak_hold=False, show_gauge=True, ) self.Add(self.wxgui_numbersink2_0_0.win) self.wxgui_numbersink2_0 = numbersink2.number_sink_f( self.GetWin(), unit="mag", minval=-100, maxval=0, factor=20, decimal_places=10, ref_level=0, sample_rate=samp_rate, number_rate=15, average=False, avg_alpha=None, label="Magnitude", peak_hold=False, show_gauge=True, ) self.Add(self.wxgui_numbersink2_0.win) self.wxgui_fftsink2_0_0 = fftsink2.fft_sink_c( self.GetWin(), baseband_freq=0, y_per_div=10, y_divs=10, ref_level=0, ref_scale=2.0, sample_rate=samp_rate, fft_size=1024, fft_rate=15, average=False, avg_alpha=None, title="Reflect", peak_hold=False, win=window.hamming, ) self.Add(self.wxgui_fftsink2_0_0.win) self.wxgui_fftsink2_0 = fftsink2.fft_sink_c( self.GetWin(), baseband_freq=0, y_per_div=10, y_divs=10, ref_level=0, ref_scale=2.0, sample_rate=samp_rate, fft_size=1024, fft_rate=15, average=False, avg_alpha=None, title="Reference", peak_hold=False, win=window.hamming, ) self.Add(self.wxgui_fftsink2_0.win) self.gr_nlog10_ff_0 = gr.nlog10_ff(1, 1, 0) self.gr_divide_xx_0 = gr.divide_cc(1) self.gr_complex_to_mag_0 = gr.complex_to_mag(1) self.gr_complex_to_arg_0 = gr.complex_to_arg(1) self.band_pass_filter_0_0 = gr.fir_filter_fcc(1, firdes.complex_band_pass( 1, samp_rate, 4.8e3, 5.2e3, 100, firdes.WIN_HAMMING, 6.76)) self.band_pass_filter_0 = gr.fir_filter_fcc(1, firdes.complex_band_pass( 1, samp_rate, 4.8e3, 5.2e3, 100, firdes.WIN_HAMMING, 6.76)) self.audio_source_0 = audio.source(samp_rate, "", True) ################################################## # Connections ################################################## self.connect((self.audio_source_0, 0), (self.band_pass_filter_0, 0)) self.connect((self.band_pass_filter_0, 0), (self.wxgui_fftsink2_0, 0)) self.connect((self.audio_source_0, 1), (self.band_pass_filter_0_0, 0)) self.connect((self.band_pass_filter_0_0, 0), (self.wxgui_fftsink2_0_0, 0)) self.connect((self.band_pass_filter_0, 0), (self.gr_divide_xx_0, 0)) self.connect((self.band_pass_filter_0_0, 0), (self.gr_divide_xx_0, 1)) self.connect((self.gr_divide_xx_0, 0), (self.gr_complex_to_arg_0, 0)) self.connect((self.gr_complex_to_arg_0, 0), (self.wxgui_numbersink2_0_0, 0)) self.connect((self.gr_complex_to_mag_0, 0), (self.gr_nlog10_ff_0, 0)) self.connect((self.gr_nlog10_ff_0, 0), (self.wxgui_numbersink2_0, 0)) self.connect((self.band_pass_filter_0_0, 0), (self.gr_complex_to_mag_0, 0))
def __init__ (self, demod_rate, audio_decimation):
"""
Hierarchical block for demodulating a broadcast FM signal.
The input is the downconverted complex baseband signal
(gr_complex). The output is two streams of the demodulated
audio (float) 0=Left, 1=Right.
Args:
demod_rate: input sample rate of complex baseband input. (float)
audio_decimation: how much to decimate demod_rate to get to audio. (integer)
"""
gr.hier_block2.__init__(self, "wfm_rcv_fmdet",
gr.io_signature(1, 1, gr.sizeof_gr_complex), # Input signature
gr.io_signature(2, 2, gr.sizeof_float)) # Output signature
lowfreq = -125e3/demod_rate
highfreq = 125e3/demod_rate
audio_rate = demod_rate / audio_decimation
# We assign to self so that outsiders can grab the demodulator
# if they need to. E.g., to plot its output.
#
# input: complex; output: float
self.fm_demod = gr.fmdet_cf (demod_rate, lowfreq, highfreq, 0.05)
# input: float; output: float
self.deemph_Left = fm_deemph (audio_rate)
self.deemph_Right = fm_deemph (audio_rate)
# compute FIR filter taps for audio filter
width_of_transition_band = audio_rate / 32
audio_coeffs = gr.firdes.low_pass (1.0 , # gain
demod_rate, # sampling rate
15000 ,
width_of_transition_band,
gr.firdes.WIN_HAMMING)
# input: float; output: float
self.audio_filter = gr.fir_filter_fff (audio_decimation, audio_coeffs)
if 1:
# Pick off the stereo carrier/2 with this filter. It
# attenuated 10 dB so apply 10 dB gain We pick off the
# negative frequency half because we want to base band by
# it!
## NOTE THIS WAS HACKED TO OFFSET INSERTION LOSS DUE TO
## DEEMPHASIS
stereo_carrier_filter_coeffs = gr.firdes.complex_band_pass(10.0,
demod_rate,
-19020,
-18980,
width_of_transition_band,
gr.firdes.WIN_HAMMING)
#print "len stereo carrier filter = ",len(stereo_carrier_filter_coeffs)
#print "stereo carrier filter ", stereo_carrier_filter_coeffs
#print "width of transition band = ",width_of_transition_band, " audio rate = ", audio_rate
# Pick off the double side band suppressed carrier
# Left-Right audio. It is attenuated 10 dB so apply 10 dB
# gain
stereo_dsbsc_filter_coeffs = gr.firdes.complex_band_pass(20.0,
demod_rate,
38000-15000/2,
38000+15000/2,
width_of_transition_band,
gr.firdes.WIN_HAMMING)
#print "len stereo dsbsc filter = ",len(stereo_dsbsc_filter_coeffs)
#print "stereo dsbsc filter ", stereo_dsbsc_filter_coeffs
# construct overlap add filter system from coefficients
# for stereo carrier
self.stereo_carrier_filter = gr.fir_filter_fcc(audio_decimation,
stereo_carrier_filter_coeffs)
# carrier is twice the picked off carrier so arrange to do
# a commplex multiply
self.stereo_carrier_generator = gr.multiply_cc();
# Pick off the rds signal
stereo_rds_filter_coeffs = gr.firdes.complex_band_pass(30.0,
demod_rate,
57000 - 1500,
57000 + 1500,
width_of_transition_band,
gr.firdes.WIN_HAMMING)
#print "len stereo dsbsc filter = ",len(stereo_dsbsc_filter_coeffs)
#print "stereo dsbsc filter ", stereo_dsbsc_filter_coeffs
# construct overlap add filter system from coefficients for stereo carrier
self.rds_signal_filter = gr.fir_filter_fcc(audio_decimation,
stereo_rds_filter_coeffs)
self.rds_carrier_generator = gr.multiply_cc();
self.rds_signal_generator = gr.multiply_cc();
self_rds_signal_processor = gr.null_sink(gr.sizeof_gr_complex);
loop_bw = 2*math.pi/100.0
max_freq = -2.0*math.pi*18990/audio_rate;
min_freq = -2.0*math.pi*19010/audio_rate;
self.stereo_carrier_pll_recovery = gr.pll_refout_cc(loop_bw,
max_freq,
min_freq);
#self.stereo_carrier_pll_recovery.squelch_enable(False)
##pll_refout does not have squelch yet, so disabled for
#now
# set up mixer (multiplier) to get the L-R signal at
# baseband
self.stereo_basebander = gr.multiply_cc();
# pick off the real component of the basebanded L-R
# signal. The imaginary SHOULD be zero
self.LmR_real = gr.complex_to_real();
self.Make_Left = gr.add_ff();
self.Make_Right = gr.sub_ff();
self.stereo_dsbsc_filter = gr.fir_filter_fcc(audio_decimation,
stereo_dsbsc_filter_coeffs)
if 1:
# send the real signal to complex filter to pick off the
# carrier and then to one side of a multiplier
self.connect (self, self.fm_demod, self.stereo_carrier_filter,
self.stereo_carrier_pll_recovery,
(self.stereo_carrier_generator,0))
# send the already filtered carrier to the otherside of the carrier
# the resulting signal from this multiplier is the carrier
# with correct phase but at -38000 Hz.
self.connect (self.stereo_carrier_pll_recovery, (self.stereo_carrier_generator,1))
# send the new carrier to one side of the mixer (multiplier)
self.connect (self.stereo_carrier_generator, (self.stereo_basebander,0))
# send the demphasized audio to the DSBSC pick off filter, the complex
# DSBSC signal at +38000 Hz is sent to the other side of the mixer/multiplier
# the result is BASEBANDED DSBSC with phase zero!
self.connect (self.fm_demod,self.stereo_dsbsc_filter, (self.stereo_basebander,1))
# Pick off the real part since the imaginary is
# theoretically zero and then to one side of a summer
self.connect (self.stereo_basebander, self.LmR_real, (self.Make_Left,0))
#take the same real part of the DSBSC baseband signal and
#send it to negative side of a subtracter
self.connect (self.LmR_real,(self.Make_Right,1))
# Make rds carrier by taking the squared pilot tone and
# multiplying by pilot tone
self.connect (self.stereo_basebander,(self.rds_carrier_generator,0))
self.connect (self.stereo_carrier_pll_recovery,(self.rds_carrier_generator,1))
# take signal, filter off rds, send into mixer 0 channel
self.connect (self.fm_demod,self.rds_signal_filter,(self.rds_signal_generator,0))
# take rds_carrier_generator output and send into mixer 1
# channel
self.connect (self.rds_carrier_generator,(self.rds_signal_generator,1))
# send basebanded rds signal and send into "processor"
# which for now is a null sink
self.connect (self.rds_signal_generator,self_rds_signal_processor)
if 1:
# pick off the audio, L+R that is what we used to have and
# send it to the summer
self.connect(self.fm_demod, self.audio_filter, (self.Make_Left, 1))
# take the picked off L+R audio and send it to the PLUS
# side of the subtractor
self.connect(self.audio_filter,(self.Make_Right, 0))
# The result of Make_Left gets (L+R) + (L-R) and results in 2*L
# The result of Make_Right gets (L+R) - (L-R) and results in 2*R
self.connect(self.Make_Left , self.deemph_Left, (self, 0))
self.connect(self.Make_Right, self.deemph_Right, (self, 1))
