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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 3, 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, blks2
from usrp_source import usrp_source_c
_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.top_block):
def __init__(self, options):
gr.top_block.__init__(self, "dect_receiver")
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(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 = blks2.gmsk_demod(samples_per_symbol=if_rate/_dect_symbol_rate,
verbose=options.verbose)
self._sink = gr.null_sink(gr.sizeof_char)
self.connect(self._usrp, self._channel_filter, self._demod, self._sink)
# 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.baseband_log = gr.file_sink(gr.sizeof_gr_complex, options.log_baseband)
self.connect(self._channel_filter, self.baseband_log)
# 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.demod_log = gr.file_sink(gr.sizeof_char, options.log_demod)
self.connect(self._demod, self.demod_log)
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