3 # Copyright 2005,2006,2007 Free Software Foundation, Inc.
5 # This file is part of GNU Radio
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)
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.
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.
23 from gnuradio import gr, gru, blks2
24 from gnuradio import eng_notation
28 # /////////////////////////////////////////////////////////////////////////////
30 # /////////////////////////////////////////////////////////////////////////////
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
39 options = copy.copy(options) # make a copy so we can destructively modify
41 self._verbose = options.verbose
42 self._bitrate = options.bitrate # desired bit rate
43 self._samples_per_symbol = options.samples_per_symbol # desired samples/symbol
45 self._rx_callback = rx_callback # this callback is fired when there's a packet available
46 self._demod_class = demod_class # the demodulator_class we're using
49 demod_kwargs = self._demod_class.extract_kwargs_from_options(options)
51 # Design filter to get actual channel we want
53 chan_coeffs = gr.firdes.low_pass (1.0, # gain
54 sw_decim * self._samples_per_symbol, # sampling rate
55 1.0, # midpoint of trans. band
56 0.5, # width of trans. band
57 gr.firdes.WIN_HANN) # filter type
58 self.channel_filter = gr.fft_filter_ccc(sw_decim, chan_coeffs)
61 self.packet_receiver = \
62 blks2.demod_pkts(self._demod_class(**demod_kwargs),
64 callback=self._rx_callback,
67 # Carrier Sensing Blocks
69 thresh = 30 # in dB, will have to adjust
70 self.probe = gr.probe_avg_mag_sqrd_c(thresh,alpha)
72 # Display some information about the setup
76 # connect block input to channel filter
77 self.connect(self, self.channel_filter)
79 # connect the channel input filter to the carrier power detector
80 self.connect(self.channel_filter, self.probe)
82 # connect channel filter to the packet receiver
83 self.connect(self.channel_filter, self.packet_receiver)
88 def samples_per_symbol(self):
89 return self._samples_per_symbol
91 def carrier_sensed(self):
93 Return True if we think carrier is present.
95 #return self.probe.level() > X
96 return self.probe.unmuted()
98 def carrier_threshold(self):
100 Return current setting in dB.
102 return self.probe.threshold()
104 def set_carrier_threshold(self, threshold_in_db):
106 Set carrier threshold.
108 @param threshold_in_db: set detection threshold
109 @type threshold_in_db: float (dB)
111 self.probe.set_threshold(threshold_in_db)
114 def add_options(normal, expert):
116 Adds receiver-specific options to the Options Parser
118 if not normal.has_option("--bitrate"):
119 normal.add_option("-r", "--bitrate", type="eng_float", default=100e3,
120 help="specify bitrate [default=%default].")
121 normal.add_option("-v", "--verbose", action="store_true", default=False)
122 expert.add_option("-S", "--samples-per-symbol", type="float", default=None,
123 help="set samples/symbol [default=%default]")
124 expert.add_option("", "--log", action="store_true", default=False,
125 help="Log all parts of flow graph to files (CAUTION: lots of data)")
127 # Make a static method to call before instantiation
128 add_options = staticmethod(add_options)
131 def _print_verbage(self):
133 Prints information about the receive path
135 print "\nReceive Path:"
136 print "modulation: %s" % (self._demod_class.__name__)
137 print "bitrate: %sb/s" % (eng_notation.num_to_str(self._bitrate))
138 print "samples/symbol: %.4f" % (self._samples_per_symbol)