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   1 #!/usr/bin/env python
   2 #
   3 # Copyright 2005,2006,2007 Free Software Foundation, Inc.
   4 #
   5 # This file is part of GNU Radio
   6 #
   7 # GNU Radio is free software; you can redistribute it and/or modify
   8 # it under the terms of the GNU General Public License as published by
   9 # the Free Software Foundation; either version 3, or (at your option)
  10 # any later version.
  11 #
  12 # GNU Radio is distributed in the hope that it will be useful,
  13 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 # GNU General Public License for more details.
  16 #
  17 # You should have received a copy of the GNU General Public License
  18 # along with GNU Radio; see the file COPYING.  If not, write to
  19 # the Free Software Foundation, Inc., 51 Franklin Street,
  20 # Boston, MA 02110-1301, USA.
  21 #
  22
  23 from gnuradio import gr, gru, blks2
  24 from gnuradio import usrp
  25 from gnuradio import eng_notation
  26 import copy
  27 import sys
  28
  29 # from current dir
  30 from pick_bitrate import pick_rx_bitrate
  31
  32 # /////////////////////////////////////////////////////////////////////////////
  33 #                              receive path
  34 # /////////////////////////////////////////////////////////////////////////////
  35
  36 class receive_path(gr.hier_block2):
  37     def __init__(self, demod_class, rx_callback, options):
  38
  39         gr.hier_block2.__init__(self, "receive_path",
  40                                 gr.io_signature(0, 0, 0), # Input signature
  41                                 gr.io_signature(0, 0, 0)) # Output signature
  42
  43         options = copy.copy(options)    # make a copy so we can destructively modify
  44
  45         self._which              = options.which           # the USRP board attached
  46         self._verbose            = options.verbose
  47         self._rx_freq            = options.rx_freq         # receiver's center frequency
  48         self._rx_gain            = options.rx_gain         # receiver's gain
  49         self._rx_subdev_spec     = options.rx_subdev_spec  # daughterboard to use
  50         self._bitrate            = options.bitrate         # desired bit rate
  51         self._decim              = options.decim           # Decimating rate for the USRP (prelim)
  52         self._samples_per_symbol = options.samples_per_symbol  # desired samples/symbol
  53         self._fusb_block_size    = options.fusb_block_size # usb info for USRP
  54         self._fusb_nblocks       = options.fusb_nblocks    # usb info for USRP
  55
  56         self._rx_callback   = rx_callback      # this callback is fired when there's a packet available
  57         self._demod_class   = demod_class      # the demodulator_class we're using
  58
  59         if self._rx_freq is None:
  60             sys.stderr.write("-f FREQ or --freq FREQ or --rx-freq FREQ must be specified\n")
  61             raise SystemExit
  62
  63         # Set up USRP source; also adjusts decim, samples_per_symbol, and bitrate
  64         self._setup_usrp_source()
  65
  66         g = self.subdev.gain_range()
  67         if options.show_rx_gain_range:
  68             print "Rx Gain Range: minimum = %g, maximum = %g, step size = %g" \
  69                   % (g[0], g[1], g[2])
  70
  71         self.set_gain(options.rx_gain)
  72
  73         self.set_auto_tr(True)                 # enable Auto Transmit/Receive switching
  74
  75         # Set RF frequency
  76         ok = self.set_freq(self._rx_freq)
  77         if not ok:
  78             print "Failed to set Rx frequency to %s" % (eng_notation.num_to_str(self._rx_freq))
  79             raise ValueError, eng_notation.num_to_str(self._rx_freq)
  80
  81         # copy the final answers back into options for use by demodulator
  82         options.samples_per_symbol = self._samples_per_symbol
  83         options.bitrate = self._bitrate
  84         options.decim = self._decim
  85
  86         # Get demod_kwargs
  87         demod_kwargs = self._demod_class.extract_kwargs_from_options(options)
  88
  89         # Design filter to get actual channel we want
  90         sw_decim = 1
  91         chan_coeffs = gr.firdes.low_pass (1.0,                  # gain
  92                                           sw_decim * self._samples_per_symbol, # sampling rate
  93                                           1.0,                  # midpoint of trans. band
  94                                           0.5,                  # width of trans. band
  95                                           gr.firdes.WIN_HANN)   # filter type
  96
  97         # Decimating channel filter
  98         # complex in and out, float taps
  99         self.chan_filt = gr.fft_filter_ccc(sw_decim, chan_coeffs)
 100         #self.chan_filt = gr.fir_filter_ccf(sw_decim, chan_coeffs)
 101
 102         # receiver
 103         self.packet_receiver = \
 104             blks2.demod_pkts(self._demod_class(**demod_kwargs),
 105                              access_code=None,
 106                              callback=self._rx_callback,
 107                              threshold=-1)
 108
 109         # Carrier Sensing Blocks
 110         alpha = 0.001
 111         thresh = 30   # in dB, will have to adjust
 112
 113         if options.log_rx_power == True:
 114             self.probe = gr.probe_avg_mag_sqrd_cf(thresh,alpha)
 115             self.power_sink = gr.file_sink(gr.sizeof_float, "rxpower.dat")
 116             self.connect(self.chan_filt, self.probe, self.power_sink)
 117         else:
 118             self.probe = gr.probe_avg_mag_sqrd_c(thresh,alpha)
 119             self.connect(self.chan_filt, self.probe)
 120
 121         # Display some information about the setup
 122         if self._verbose:
 123             self._print_verbage()
 124
 125         self.connect(self.u, self.chan_filt, self.packet_receiver)
 126
 127     def _setup_usrp_source(self):
 128         self.u = usrp.source_c (self._which,
 129                                 fusb_block_size=self._fusb_block_size,
 130                                 fusb_nblocks=self._fusb_nblocks)
 131         adc_rate = self.u.adc_rate()
 132
 133         # derive values of bitrate, samples_per_symbol, and decim from desired info
 134         (self._bitrate, self._samples_per_symbol, self._decim) = \
 135             pick_rx_bitrate(self._bitrate, self._demod_class.bits_per_symbol(), \
 136                             self._samples_per_symbol, self._decim, adc_rate)
 137
 138         self.u.set_decim_rate(self._decim)
 139
 140         # determine the daughterboard subdevice we're using
 141         if self._rx_subdev_spec is None:
 142             self._rx_subdev_spec = usrp.pick_rx_subdevice(self.u)
 143         self.subdev = usrp.selected_subdev(self.u, self._rx_subdev_spec)
 144
 145         self.u.set_mux(usrp.determine_rx_mux_value(self.u, self._rx_subdev_spec))
 146
 147     def set_freq(self, target_freq):
 148         """
 149         Set the center frequency we're interested in.
 150
 151         @param target_freq: frequency in Hz
 152         @rypte: bool
 153
 154         Tuning is a two step process.  First we ask the front-end to
 155         tune as close to the desired frequency as it can.  Then we use
 156         the result of that operation and our target_frequency to
 157         determine the value for the digital up converter.
 158         """
 159         r = self.u.tune(0, self.subdev, target_freq)
 160         if r:
 161             return True
 162
 163         return False
 164
 165     def set_gain(self, gain):
 166         """
 167         Sets the analog gain in the USRP
 168         """
 169         if gain is None:
 170             r = self.subdev.gain_range()
 171             gain = (r[0] + r[1])/2               # set gain to midpoint
 172         self.gain = gain
 173         return self.subdev.set_gain(gain)
 174
 175     def set_auto_tr(self, enable):
 176         return self.subdev.set_auto_tr(enable)
 177
 178     def bitrate(self):
 179         return self._bitrate
 180
 181     def samples_per_symbol(self):
 182         return self._samples_per_symbol
 183
 184     def decim(self):
 185         return self._decim
 186
 187     def carrier_sensed(self):
 188         """
 189         Return True if we think carrier is present.
 190         """
 191         #return self.probe.level() > X
 192         return self.probe.unmuted()
 193
 194     def carrier_threshold(self):
 195         """
 196         Return current setting in dB.
 197         """
 198         return self.probe.threshold()
 199
 200     def set_carrier_threshold(self, threshold_in_db):
 201         """
 202         Set carrier threshold.
 203
 204         @param threshold_in_db: set detection threshold
 205         @type threshold_in_db:  float (dB)
 206         """
 207         self.probe.set_threshold(threshold_in_db)
 208
 209
 210     def add_options(normal, expert):
 211         """
 212         Adds receiver-specific options to the Options Parser
 213         """
 214         add_freq_option(normal)
 215         if not normal.has_option("--bitrate"):
 216             normal.add_option("-r", "--bitrate", type="eng_float", default=None,
 217                               help="specify bitrate.  samples-per-symbol and interp/decim will be derived.")
 218         normal.add_option("-w", "--which", type="int", default=0,
 219                           help="select USRP board [default=%default]")
 220         normal.add_option("-R", "--rx-subdev-spec", type="subdev", default=None,
 221                           help="select USRP Rx side A or B")
 222         normal.add_option("", "--rx-gain", type="eng_float", default=None, metavar="GAIN",
 223                           help="set receiver gain in dB [default=midpoint].  See also --show-rx-gain-range")
 224         normal.add_option("", "--show-rx-gain-range", action="store_true", default=False,
 225                           help="print min and max Rx gain available on selected daughterboard")
 226         normal.add_option("-v", "--verbose", action="store_true", default=False)
 227         expert.add_option("-S", "--samples-per-symbol", type="int", default=None,
 228                           help="set samples/symbol [default=%default]")
 229         expert.add_option("", "--rx-freq", type="eng_float", default=None,
 230                           help="set Rx frequency to FREQ [default=%default]", metavar="FREQ")
 231         expert.add_option("-d", "--decim", type="intx", default=None,
 232                           help="set fpga decimation rate to DECIM [default=%default]")
 233         expert.add_option("", "--log", action="store_true", default=False,
 234                           help="Log all parts of flow graph to files (CAUTION: lots of data)")
 235         expert.add_option("", "--log-rx-power", action="store_true", default=False,
 236                           help="Log receive signal power to file (CAUTION: lots of data)")
 237
 238     # Make a static method to call before instantiation
 239     add_options = staticmethod(add_options)
 240
 241
 242     def _print_verbage(self):
 243         """
 244         Prints information about the receive path
 245         """
 246         print "\nReceive Path:"
 247         print "Using RX d'board %s"    % (self.subdev.side_and_name(),)
 248         print "Rx gain:         %g"    % (self.gain,)
 249         print "modulation:      %s"    % (self._demod_class.__name__)
 250         print "bitrate:         %sb/s" % (eng_notation.num_to_str(self._bitrate))
 251         print "samples/symbol:  %3d"   % (self._samples_per_symbol)
 252         print "decim:           %3d"   % (self._decim)
 253         print "Rx Frequency:    %s"    % (eng_notation.num_to_str(self._rx_freq))
 254         # print "Rx Frequency:    %f"    % (self._rx_freq)
 255
 256     def __del__(self):
 257         # Avoid weak reference error
 258         del self.subdev
 259
 260 def add_freq_option(parser):
 261     """
 262     Hackery that has the -f / --freq option set both tx_freq and rx_freq
 263     """
 264     def freq_callback(option, opt_str, value, parser):
 265         parser.values.rx_freq = value
 266         parser.values.tx_freq = value
 267
 268     if not parser.has_option('--freq'):
 269         parser.add_option('-f', '--freq', type="eng_float",
 270                           action="callback", callback=freq_callback,
 271                           help="set Tx and/or Rx frequency to FREQ [default=%default]",
 272                           metavar="FREQ")