--- /dev/null
+#!/usr/bin/env python
+#
+# Copyright 2005,2006 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, gru, blks
+from gnuradio import usrp
+from gnuradio import eng_notation
+import copy
+import sys
+
+# from current dir
+from pick_bitrate import pick_rx_bitrate
+
+# /////////////////////////////////////////////////////////////////////////////
+# receive path
+# /////////////////////////////////////////////////////////////////////////////
+
+class receive_path(gr.hier_block):
+ def __init__(self, fg, demod_class, rx_callback, options):
+
+ options = copy.copy(options) # make a copy so we can destructively modify
+
+ self._verbose = options.verbose
+ self._rx_freq = options.rx_freq # receiver's center frequency
+ self._rx_gain = options.rx_gain # receiver's gain
+ self._rx_subdev_spec = options.rx_subdev_spec # daughterboard to use
+ self._bitrate = options.bitrate # desired bit rate
+ self._decim = options.decim # Decimating rate for the USRP (prelim)
+ self._samples_per_symbol = options.samples_per_symbol # desired samples/symbol
+ self._fusb_block_size = options.fusb_block_size # usb info for USRP
+ self._fusb_nblocks = options.fusb_nblocks # usb info for USRP
+
+ self._rx_callback = rx_callback # this callback is fired when there's a packet available
+ self._demod_class = demod_class # the demodulator_class we're using
+
+ if self._rx_freq is None:
+ sys.stderr.write("-f FREQ or --freq FREQ or --rx-freq FREQ must be specified\n")
+ raise SystemExit
+
+ # Set up USRP source; also adjusts decim, samples_per_symbol, and bitrate
+ self._setup_usrp_source()
+
+ # copy the final answers back into options for use by demodulator
+ options.samples_per_symbol = self._samples_per_symbol
+ options.bitrate = self._bitrate
+ options.decim = self._decim
+
+ # Get demod_kwargs
+ demod_kwargs = self._demod_class.extract_kwargs_from_options(options)
+
+ # Design filter to get actual channel we want
+ sw_decim = 1
+ chan_coeffs = gr.firdes.low_pass (1.0, # gain
+ sw_decim * self._samples_per_symbol, # sampling rate
+ 1.0, # midpoint of trans. band
+ 0.1, # width of trans. band
+ gr.firdes.WIN_HANN) # filter type
+
+ # Decimating channel filter
+ # complex in and out, float taps
+ self.chan_filt = gr.fft_filter_ccc(sw_decim, chan_coeffs)
+ #self.chan_filt = gr.fir_filter_ccf(sw_decim, chan_coeffs)
+
+ # receiver
+ self.packet_receiver = \
+ blks.demod_pkts(fg,
+ self._demod_class(fg, **demod_kwargs),
+ access_code=None,
+ callback=self._rx_callback,
+ threshold=-1)
+
+ ok = self.set_freq(self._rx_freq)
+ if not ok:
+ print "Failed to set Rx frequency to %s" % (eng_notation.num_to_str(self._rx_freq))
+ raise ValueError, eng_notation.num_to_str(self._rx_freq)
+
+ g = self.subdev.gain_range()
+ if options.show_rx_gain_range:
+ print "Rx Gain Range: minimum = %g, maximum = %g, step size = %g" \
+ % (g[0], g[1], g[2])
+
+ self.set_gain(options.rx_gain)
+
+ self.set_auto_tr(True) # enable Auto Transmit/Receive switching
+
+ # Carrier Sensing Blocks
+ alpha = 0.001
+ thresh = 30 # in dB, will have to adjust
+ self.probe = gr.probe_avg_mag_sqrd_c(thresh,alpha)
+ fg.connect(self.chan_filt, self.probe)
+
+ # Display some information about the setup
+ if self._verbose:
+ self._print_verbage()
+
+ fg.connect(self.u, self.chan_filt, self.packet_receiver)
+ gr.hier_block.__init__(self, fg, None, None)
+
+ def _setup_usrp_source(self):
+ self.u = usrp.source_c (fusb_block_size=self._fusb_block_size,
+ fusb_nblocks=self._fusb_nblocks)
+ adc_rate = self.u.adc_rate()
+
+ # derive values of bitrate, samples_per_symbol, and decim from desired info
+ (self._bitrate, self._samples_per_symbol, self._decim) = \
+ pick_rx_bitrate(self._bitrate, self._demod_class.bits_per_symbol(), \
+ self._samples_per_symbol, self._decim, adc_rate)
+
+ self.u.set_decim_rate(self._decim)
+
+ # determine the daughterboard subdevice we're using
+ if self._rx_subdev_spec is None:
+ self._rx_subdev_spec = usrp.pick_rx_subdevice(self.u)
+ self.subdev = usrp.selected_subdev(self.u, self._rx_subdev_spec)
+
+ self.u.set_mux(usrp.determine_rx_mux_value(self.u, self._rx_subdev_spec))
+
+ def set_freq(self, target_freq):
+ """
+ Set the center frequency we're interested in.
+
+ @param target_freq: frequency in Hz
+ @rypte: bool
+
+ Tuning is a two step process. First we ask the front-end to
+ tune as close to the desired frequency as it can. Then we use
+ the result of that operation and our target_frequency to
+ determine the value for the digital up converter.
+ """
+ r = self.u.tune(0, self.subdev, target_freq)
+ if r:
+ return True
+
+ return False
+
+ def set_gain(self, gain):
+ """
+ Sets the analog gain in the USRP
+ """
+ if gain is None:
+ r = self.subdev.gain_range()
+ gain = (r[0] + r[1])/2 # set gain to midpoint
+ self.gain = gain
+ return self.subdev.set_gain(gain)
+
+ def set_auto_tr(self, enable):
+ return self.subdev.set_auto_tr(enable)
+
+ def bitrate(self):
+ return self._bitrate
+
+ def samples_per_symbol(self):
+ return self._samples_per_symbol
+
+ def decim(self):
+ return self._decim
+
+ def carrier_sensed(self):
+ """
+ Return True if we think carrier is present.
+ """
+ #return self.probe.level() > X
+ return self.probe.unmuted()
+
+ def carrier_threshold(self):
+ """
+ Return current setting in dB.
+ """
+ return self.probe.threshold()
+
+ def set_carrier_threshold(self, threshold_in_db):
+ """
+ Set carrier threshold.
+
+ @param threshold_in_db: set detection threshold
+ @type threshold_in_db: float (dB)
+ """
+ self.probe.set_threshold(threshold_in_db)
+
+
+ def add_options(normal, expert):
+ """
+ Adds receiver-specific options to the Options Parser
+ """
+ add_freq_option(normal)
+ if not normal.has_option("--bitrate"):
+ normal.add_option("-r", "--bitrate", type="eng_float", default=None,
+ help="specify bitrate. samples-per-symbol and interp/decim will be derived.")
+ normal.add_option("-R", "--rx-subdev-spec", type="subdev", default=None,
+ help="select USRP Rx side A or B")
+ normal.add_option("", "--rx-gain", type="eng_float", default=None, metavar="GAIN",
+ help="set receiver gain in dB [default=midpoint]. See also --show-rx-gain-range")
+ normal.add_option("", "--show-rx-gain-range", action="store_true", default=False,
+ help="print min and max Rx gain available on selected daughterboard")
+ normal.add_option("-v", "--verbose", action="store_true", default=False)
+ expert.add_option("-S", "--samples-per-symbol", type="int", default=None,
+ help="set samples/symbol [default=%default]")
+ expert.add_option("", "--rx-freq", type="eng_float", default=None,
+ help="set Rx frequency to FREQ [default=%default]", metavar="FREQ")
+ expert.add_option("-d", "--decim", type="intx", default=None,
+ help="set fpga decimation rate to DECIM [default=%default]")
+ expert.add_option("", "--log", action="store_true", default=False,
+ help="Log all parts of flow graph to files (CAUTION: lots of data)")
+
+ # Make a static method to call before instantiation
+ add_options = staticmethod(add_options)
+
+
+ def _print_verbage(self):
+ """
+ Prints information about the receive path
+ """
+ print "Using RX d'board %s" % (self.subdev.side_and_name(),)
+ print "Rx gain: %g" % (self.gain,)
+ print "modulation: %s" % (self._demod_class.__name__)
+ print "bitrate: %sb/s" % (eng_notation.num_to_str(self._bitrate))
+ print "samples/symbol: %3d" % (self._samples_per_symbol)
+ print "decim: %3d" % (self._decim)
+ print "Rx Frequency: %s" % (eng_notation.num_to_str(self._rx_freq))
+ # print "Rx Frequency: %f" % (self._rx_freq)
+
+def add_freq_option(parser):
+ """
+ Hackery that has the -f / --freq option set both tx_freq and rx_freq
+ """
+ def freq_callback(option, opt_str, value, parser):
+ parser.values.rx_freq = value
+ parser.values.tx_freq = value
+
+ if not parser.has_option('--freq'):
+ parser.add_option('-f', '--freq', type="eng_float",
+ action="callback", callback=freq_callback,
+ help="set Tx and/or Rx frequency to FREQ [default=%default]",
+ metavar="FREQ")
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