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#!/usr/bin/env python
#
# Copyright 2007 Free Software Foundation, Inc.
#
# This file is part of GNU Radio
#
# GNU Radio 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 2, or (at your option)
# any later version.
#
# GNU Radio 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 GNU Radio; see the file COPYING. If not, write to
# the Free Software Foundation, Inc., 51 Franklin Street,
# Boston, MA 02110-1301, USA.
#
from gnuradio import gr, optfir
from usrp_source import usrp_source_c
from gmsk2 import gmsk2_demod
_dect_symbol_rate = 1.152e6
_dect_occupied_bandwidth = _dect_symbol_rate * 1.03 # BT=0.5
_dect_channel_bandwidth = 1.728e6
# Top-level hierarchical block that implements DECT demodulation and
# decoding.
class dect_receiver(gr.hier_block2):
def __init__(self, options):
gr.hier_block2.__init__(self,
"dect_receiver", # Block typename
gr.io_signature(0,0,0), # Input signature
gr.io_signature(0,0,0)) # Output signature
self._options = options
# Need greater than 2 samples per symbol. This makes a decimation
# rate of 26 and a samples per symbol of 2.136752
if_rate = 2.461538e6
self._usrp = usrp_source_c(self,
which=0,
subdev_spec=options.rx_subdev_spec,
if_rate=if_rate,
gain=options.gain,
freq=options.freq,
calibration=options.calibration,
verbose=options.verbose)
# Filter baseband to 1.186 MHz passband, 1.728 MHz stopband
chan_taps = optfir.low_pass(1.0, # Gain
if_rate, # Sample rate
_dect_occupied_bandwidth/2, # One sided modulation bandwidth
_dect_channel_bandwidth/2, # One sided channel bandwidth
1.0, # Passband ripple (db)
60) # Stopband attenuation (db)
if self._options.verbose:
print "Channel filter has", len(chan_taps), "taps"
self._channel_filter = gr.freq_xlating_fir_filter_ccf(1, # Decimation rate
chan_taps, # Filter taps
0.0, # Offset frequency
if_rate) # Sample rate
self._demod = gmsk2_demod(samples_per_symbol=if_rate/_dect_symbol_rate,
verbose=options.verbose)
# Define and connect components
self.define_component("usrp", self._usrp)
self.define_component("channel", self._channel_filter)
self.define_component("demod", self._demod)
self.define_component("sink", gr.null_sink(gr.sizeof_char))
self.connect("usrp", 0, "channel", 0)
self.connect("channel", 0, "demod", 0)
self.connect("demod", 0, "sink", 0)
# Log baseband to file if requested
if options.log_baseband is not None:
if options.verbose:
print "Logging baseband to file", options.log_baseband
self.define_component("baseband_log", gr.file_sink(gr.sizeof_gr_complex, options.log_baseband))
self.connect("channel", 0, "baseband_log", 0)
# Log demodulator output to file if requested
if options.log_demod is not None:
if options.verbose:
print "Logging demodulator to file", options.log_demod
self.define_component("demod_log", gr.file_sink(gr.sizeof_char, options.log_demod))
self.connect("demod", 0, "demod_log", 0)
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