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#
# Copyright 2005,2006,2007 Free Software Foundation, Inc.
#
# OP25 Demodulator Block
# Copyright 2009, 2010, 2011, 2012, 2013, 2014, 2015 Max H. Parke KA1RBI
#
# This file is part of GNU Radio and part of OP25
#
# This is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3, or (at your option)
# any later version.
#
# It is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this; see the file COPYING. If not, write to
# the Free Software Foundation, Inc., 51 Franklin Street,
# Boston, MA 02110-1301, USA.
#
"""
P25 C4FM/CQPSK demodulation block.
"""
import sys
from gnuradio import gr, gru, eng_notation
from gnuradio import filter, analog, digital, blocks
from gnuradio.eng_option import eng_option
import op25
import op25_repeater
from math import pi
sys.path.append('tx')
import op25_c4fm_mod
# default values (used in __init__ and add_options)
_def_output_sample_rate = 48000
_def_if_rate = 24000
_def_gain_mu = 0.025
_def_costas_alpha = 0.04
_def_symbol_rate = 4800
_def_symbol_deviation = 600.0
_def_bb_gain = 1.0
# /////////////////////////////////////////////////////////////////////////////
# demodulator
# /////////////////////////////////////////////////////////////////////////////
class p25_demod_base(gr.hier_block2):
def __init__(self,
if_rate = None,
symbol_rate = _def_symbol_rate):
"""
Hierarchical block for P25 demodulation base class
@param if_rate: sample rate of complex input channel
@type if_rate: int
"""
self.if_rate = if_rate
self.symbol_rate = symbol_rate
self.bb_sink = None
self.baseband_amp = blocks.multiply_const_ff(_def_bb_gain)
coeffs = op25_c4fm_mod.c4fm_taps(sample_rate=self.if_rate, span=9, generator=op25_c4fm_mod.transfer_function_rx).generate()
self.symbol_filter = filter.fir_filter_fff(1, coeffs)
autotuneq = gr.msg_queue(2)
self.fsk4_demod = op25.fsk4_demod_ff(autotuneq, self.if_rate, self.symbol_rate)
levels = [ -2.0, 0.0, 2.0, 4.0 ]
self.slicer = op25_repeater.fsk4_slicer_fb(levels)
def set_baseband_gain(self, k):
self.baseband_amp.set_k(k)
def disconnect_bb(self):
# assumes lock held or init
if not self.bb_sink:
return
self.disconnect(self.bb_sink[0], self.bb_sink[1])
self.bb_sink = None
def connect_bb(self, src, sink):
# assumes lock held or init
self.disconnect_bb()
if src == 'symbol_filter':
self.connect(self.symbol_filter, sink)
self.bb_sink = [self.symbol_filter, sink]
elif src == 'baseband_amp':
self.connect(self.baseband_amp, sink)
self.bb_sink = [self.baseband_amp, sink]
class p25_demod_fb(p25_demod_base):
def __init__(self,
input_rate = None,
symbol_rate = _def_symbol_rate):
"""
Hierarchical block for P25 demodulation.
The float input is fsk4-demodulated
@param input_rate: sample rate of complex input channel
@type input_rate: int
"""
gr.hier_block2.__init__(self, "p25_demod_fb",
gr.io_signature(1, 1, gr.sizeof_float), # Input signature
gr.io_signature(1, 1, gr.sizeof_char)) # Output signature
p25_demod_base.__init__(self, if_rate=input_rate, symbol_rate=symbol_rate)
self.input_rate = input_rate
self.float_sink = None
self.connect(self, self.baseband_amp, self.symbol_filter, self.fsk4_demod, self.slicer, self)
def disconnect_float(self):
# assumes lock held or init
if not self.float_sink:
return
self.disconnect(self.float_sink[0], self.float_sink[1])
self.float_sink = None
def connect_float(self, sink):
# assumes lock held or init
self.disconnect_float()
self.connect(self.fsk4_demod, sink)
self.float_sink = [self.fsk4_demod, sink]
class p25_demod_cb(p25_demod_base):
def __init__(self,
input_rate = None,
demod_type = 'cqpsk',
relative_freq = 0,
offset = 0,
if_rate = _def_if_rate,
gain_mu = _def_gain_mu,
costas_alpha = _def_costas_alpha,
symbol_rate = _def_symbol_rate):
"""
Hierarchical block for P25 demodulation.
The complex input is tuned, decimated and demodulated
@param input_rate: sample rate of complex input channel
@type input_rate: int
"""
gr.hier_block2.__init__(self, "p25_demod_cb",
gr.io_signature(1, 1, gr.sizeof_gr_complex), # Input signature
gr.io_signature(1, 1, gr.sizeof_char)) # Output signature
# gr.io_signature(0, 0, 0)) # Output signature
p25_demod_base.__init__(self, if_rate=if_rate, symbol_rate=symbol_rate)
self.input_rate = input_rate
self.if_rate = if_rate
self.symbol_rate = symbol_rate
self.connect_state = None
self.offset = 0
self.sps = 0.0
self.lo_freq = 0
self.float_sink = None
self.complex_sink = None
# local osc
self.lo = analog.sig_source_c (input_rate, analog.GR_SIN_WAVE, 0, 1.0, 0)
self.mixer = blocks.multiply_cc()
lpf_coeffs = filter.firdes.low_pass(1.0, input_rate, 7250, 725, filter.firdes.WIN_HANN)
decimation = int(input_rate / if_rate)
self.lpf = filter.fir_filter_ccf(decimation, lpf_coeffs)
resampled_rate = float(input_rate) / float(decimation) # rate at output of self.lpf
self.arb_resampler = filter.pfb.arb_resampler_ccf(
float(self.if_rate) / resampled_rate)
self.connect(self, (self.mixer, 0))
self.connect(self.lo, (self.mixer, 1))
self.connect(self.mixer, self.lpf, self.arb_resampler)
levels = [ -2.0, 0.0, 2.0, 4.0 ]
self.slicer = op25_repeater.fsk4_slicer_fb(levels)
omega = float(self.if_rate) / float(self.symbol_rate)
gain_omega = 0.1 * gain_mu * gain_mu
alpha = costas_alpha
beta = 0.125 * alpha * alpha
fmax = 2400 # Hz
fmax = 2*pi * fmax / float(self.if_rate)
self.clock = op25_repeater.gardner_costas_cc(omega, gain_mu, gain_omega, alpha, beta, fmax, -fmax)
self.agc = analog.feedforward_agc_cc(16, 1.0)
# Perform Differential decoding on the constellation
self.diffdec = digital.diff_phasor_cc()
# take angle of the difference (in radians)
self.to_float = blocks.complex_to_arg()
# convert from radians such that signal is in -3/-1/+1/+3
self.rescale = blocks.multiply_const_ff( (1 / (pi / 4)) )
# fm demodulator (needed in fsk4 case)
fm_demod_gain = if_rate / (2.0 * pi * _def_symbol_deviation)
self.fm_demod = analog.quadrature_demod_cf(fm_demod_gain)
self.connect_chain(demod_type)
self.connect(self.slicer, self)
self.set_relative_frequency(relative_freq)
def set_omega(self, omega):
sps = self.if_rate / float(omega)
if sps == self.sps:
return
self.sps = sps
print 'set_omega %d %f' % (omega, sps)
self.clock.set_omega(self.sps)
def set_relative_frequency(self, freq):
if abs(freq) > self.input_rate/2:
#print 'set_relative_frequency: error, relative frequency %d exceeds limit %d' % (freq, self.input_rate/2)
return False
if freq == self.lo_freq:
return True
#print 'set_relative_frequency', freq
self.lo_freq = freq
self.lo.set_frequency(self.lo_freq)
return True
# assumes lock held or init
def disconnect_chain(self):
if self.connect_state == 'cqpsk':
self.disconnect(self.arb_resampler, self.agc, self.clock, self.diffdec, self.to_float, self.rescale, self.slicer)
elif self.connect_state == 'fsk4':
self.disconnect(self.arb_resampler, self.fm_demod, self.baseband_amp, self.symbol_filter, self.fsk4_demod, self.slicer)
self.connect_state = None
# assumes lock held or init
def connect_chain(self, demod_type):
if self.connect_state == demod_type:
return # already in desired state
self.disconnect_chain()
self.connect_state = demod_type
if demod_type == 'fsk4':
self.connect(self.arb_resampler, self.fm_demod, self.baseband_amp, self.symbol_filter, self.fsk4_demod, self.slicer)
elif demod_type == 'cqpsk':
self.connect(self.arb_resampler, self.agc, self.clock, self.diffdec, self.to_float, self.rescale, self.slicer)
else:
print 'connect_chain failed, type: %s' % demod_type
assert 0 == 1
if self.float_sink is not None:
self.connect_float(self.float_sink[1])
def disconnect_float(self):
# assumes lock held or init
if not self.float_sink:
return
self.disconnect(self.float_sink[0], self.float_sink[1])
self.float_sink = None
def connect_float(self, sink):
# assumes lock held or init
self.disconnect_float()
if self.connect_state == 'cqpsk':
self.connect(self.rescale, sink)
self.float_sink = [self.rescale, sink]
elif self.connect_state == 'fsk4':
self.connect(self.fsk4_demod, sink)
self.float_sink = [self.fsk4_demod, sink]
else:
print 'connect_float: state error', self.connect_state
assert 0 == 1
def disconnect_complex(self):
# assumes lock held or init
if not self.complex_sink:
return
self.disconnect(self.complex_sink[0], self.complex_sink[1])
self.complex_sink = None
def connect_complex(self, src, sink):
# assumes lock held or init
self.disconnect_complex()
if src == 'clock':
self.connect(self.clock, sink)
self.complex_sink = [self.clock, sink]
elif src == 'diffdec':
self.connect(self.diffdec, sink)
self.complex_sink = [self.diffdec, sink]
elif src == 'mixer':
self.connect(self.mixer, sink)
self.complex_sink = [self.mixer, sink]
elif src == 'src':
self.connect(self, sink)
self.complex_sink = [self, sink]
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