git.gag.com Git - debian/gnuradio/blob - gnuradio-examples/python/hier/digital/receive_path_lb.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 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 eng_notation
  25 import copy
  26 import sys
  27
  28 # /////////////////////////////////////////////////////////////////////////////
  29 #                              receive path
  30 # /////////////////////////////////////////////////////////////////////////////
  31
  32 class receive_path(gr.hier_block2):
  33     def __init__(self, demod_class, rx_callback, options):
  34         gr.hier_block2.__init__(self, "receive_path",
  35                                 gr.io_signature(1,1,gr.sizeof_gr_complex), # Input signature
  36                                 gr.io_signature(0,0,0))                    # Output signature
  37
  38         options = copy.copy(options)    # make a copy so we can destructively modify
  39
  40         self._verbose            = options.verbose
  41         self._bitrate            = options.bitrate         # desired bit rate
  42         self._samples_per_symbol = options.samples_per_symbol  # desired samples/symbol
  43
  44         self._rx_callback   = rx_callback      # this callback is fired when there's a packet available
  45         self._demod_class   = demod_class      # the demodulator_class we're using
  46
  47         # Get demod_kwargs
  48         demod_kwargs = self._demod_class.extract_kwargs_from_options(options)
  49
  50         # Design filter to get actual channel we want
  51         sw_decim = 1
  52         chan_coeffs = gr.firdes.low_pass (1.0,                  # gain
  53                                           sw_decim * self._samples_per_symbol, # sampling rate
  54                                           1.0,                  # midpoint of trans. band
  55                                           0.5,                  # width of trans. band
  56                                           gr.firdes.WIN_HANN)   # filter type
  57
  58         # receiver
  59         self.packet_receiver = \
  60             blks2.demod_pkts(self._demod_class(**demod_kwargs),
  61                              access_code=None,
  62                              callback=self._rx_callback,
  63                              threshold=-1)
  64
  65         # Carrier Sensing Blocks
  66         alpha = 0.001
  67         thresh = 30   # in dB, will have to adjust
  68         self.probe = gr.probe_avg_mag_sqrd_c(thresh,alpha)
  69
  70         # Display some information about the setup
  71         if self._verbose:
  72             self._print_verbage()
  73
  74         self.channel_filter = gr.fft_filter_ccc(sw_decim, chan_coeffs)
  75
  76         # connect the channel input filter to the carrier power detector
  77         self.connect(self, self.channel_filter, self.probe)
  78
  79         # connect channel filter to the packet receiver
  80         self.connect(self.channel_filter, self.packet_receiver)
  81
  82     def bitrate(self):
  83         return self._bitrate
  84
  85     def samples_per_symbol(self):
  86         return self._samples_per_symbol
  87
  88     def carrier_sensed(self):
  89         """
  90         Return True if we think carrier is present.
  91         """
  92         #return self.probe.level() > X
  93         return self.probe.unmuted()
  94
  95     def carrier_threshold(self):
  96         """
  97         Return current setting in dB.
  98         """
  99         return self.probe.threshold()
 100
 101     def set_carrier_threshold(self, threshold_in_db):
 102         """
 103         Set carrier threshold.
 104
 105         @param threshold_in_db: set detection threshold
 106         @type threshold_in_db:  float (dB)
 107         """
 108         self.probe.set_threshold(threshold_in_db)
 109
 110
 111     def add_options(normal, expert):
 112         """
 113         Adds receiver-specific options to the Options Parser
 114         """
 115         if not normal.has_option("--bitrate"):
 116             normal.add_option("-r", "--bitrate", type="eng_float", default=100e3,
 117                               help="specify bitrate [default=%default].")
 118         normal.add_option("", "--show-rx-gain-range", action="store_true", default=False,
 119                           help="print min and max Rx gain available on selected daughterboard")
 120         normal.add_option("-v", "--verbose", action="store_true", default=False)
 121         expert.add_option("-S", "--samples-per-symbol", type="int", default=2,
 122                           help="set samples/symbol [default=%default]")
 123         expert.add_option("", "--log", action="store_true", default=False,
 124                           help="Log all parts of flow graph to files (CAUTION: lots of data)")
 125
 126     # Make a static method to call before instantiation
 127     add_options = staticmethod(add_options)
 128
 129
 130     def _print_verbage(self):
 131         """
 132         Prints information about the receive path
 133         """
 134         print "modulation:      %s"    % (self._demod_class.__name__)
 135         print "bitrate:         %sb/s" % (eng_notation.num_to_str(self._bitrate))
 136         print "samples/symbol:  %3d"   % (self._samples_per_symbol)