diff options
Diffstat (limited to 'gr-analog/python/analog/fm_demod.py')
| -rw-r--r-- | gr-analog/python/analog/fm_demod.py | 59 |
1 files changed, 32 insertions, 27 deletions
diff --git a/gr-analog/python/analog/fm_demod.py b/gr-analog/python/analog/fm_demod.py index 1976a076ca..cf99b768d1 100644 --- a/gr-analog/python/analog/fm_demod.py +++ b/gr-analog/python/analog/fm_demod.py @@ -28,6 +28,7 @@ try: except ImportError: import analog_swig as analog + class fm_demod_cf(gr.hier_block2): """ Generalized FM demodulation block with deemphasis and audio @@ -36,7 +37,7 @@ class fm_demod_cf(gr.hier_block2): This block demodulates a band-limited, complex down-converted FM channel into the the original baseband signal, optionally applying deemphasis. Low pass filtering is done on the resultant signal. It - produces an output float strem in the range of [-1.0, +1.0]. + produces an output float stream in the range of [-1.0, +1.0]. Args: channel_rate: incoming sample rate of the FM baseband (integer) @@ -49,27 +50,30 @@ class fm_demod_cf(gr.hier_block2): """ def __init__(self, channel_rate, audio_decim, deviation, audio_pass, audio_stop, gain=1.0, tau=75e-6): - gr.hier_block2.__init__(self, "fm_demod_cf", - gr.io_signature(1, 1, gr.sizeof_gr_complex), # Input signature - gr.io_signature(1, 1, gr.sizeof_float)) # Output signature - - k = channel_rate/(2*pi*deviation) - QUAD = analog.quadrature_demod_cf(k) - - audio_taps = filter.optfir.low_pass(gain, # Filter gain - channel_rate, # Sample rate - audio_pass, # Audio passband - audio_stop, # Audio stopband - 0.1, # Passband ripple - 60) # Stopband attenuation - LPF = filter.fir_filter_fff(audio_decim, audio_taps) - - if tau is not None: - DEEMPH = fm_deemph(channel_rate, tau) - self.connect(self, QUAD, DEEMPH, LPF, self) + gr.hier_block2.__init__(self, "fm_demod_cf", + gr.io_signature(1, 1, gr.sizeof_gr_complex), # Input signature + gr.io_signature(1, 1, gr.sizeof_float)) # Output signature + + k = channel_rate/(2*pi*deviation) + QUAD = analog.quadrature_demod_cf(k) + + audio_taps = filter.optfir.low_pass( + gain, # Filter gain + channel_rate, # Sample rate + audio_pass, # Audio passband + audio_stop, # Audio stopband + 0.1, # Passband ripple + 60 # Stopband attenuation + ) + LPF = filter.fir_filter_fff(audio_decim, audio_taps) + + if tau is not None: + DEEMPH = fm_deemph(channel_rate, tau) + self.connect(self, QUAD, DEEMPH, LPF, self) else: self.connect(self, QUAD, LPF, self) + class demod_20k0f3e_cf(fm_demod_cf): """ NBFM demodulation block, 20 KHz channels @@ -84,9 +88,10 @@ class demod_20k0f3e_cf(fm_demod_cf): """ def __init__(self, channel_rate, audio_decim): fm_demod_cf.__init__(self, channel_rate, audio_decim, - 5000, # Deviation - 3000, # Audio passband frequency - 4500) # Audio stopband frequency + 5000, # Deviation + 3000, # Audio passband frequency + 4500) # Audio stopband frequency + class demod_200kf3e_cf(fm_demod_cf): """ @@ -101,8 +106,8 @@ class demod_200kf3e_cf(fm_demod_cf): audio_decim: input to output decimation rate (integer) """ def __init__(self, channel_rate, audio_decim): - fm_demod_cf.__init__(self, channel_rate, audio_decim, - 75000, # Deviation - 15000, # Audio passband - 16000, # Audio stopband - 20.0) # Audio gain + fm_demod_cf.__init__(self, channel_rate, audio_decim, + 75000, # Deviation + 15000, # Audio passband + 16000, # Audio stopband + 20.0) # Audio gain |