git.gag.com Git - debian/gnuradio/blob - gnuradio-examples/python/hier/digital/receive_path.py

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