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 usrp
25 from gnuradio import eng_notation
30 from pick_bitrate import pick_rx_bitrate
32 # /////////////////////////////////////////////////////////////////////////////
34 # /////////////////////////////////////////////////////////////////////////////
36 class receive_path(gr.top_block):
37 def __init__(self, demod_class, rx_callback, options):
38 gr.top_block.__init__(self, "receive_path")
39 options = copy.copy(options) # make a copy so we can destructively modify
41 self._verbose = options.verbose
42 self._rx_freq = options.rx_freq # receiver's center frequency
43 self._rx_gain = options.rx_gain # receiver's gain
44 self._rx_subdev_spec = options.rx_subdev_spec # daughterboard to use
45 self._bitrate = options.bitrate # desired bit rate
46 self._decim = options.decim # Decimating rate for the USRP (prelim)
47 self._samples_per_symbol = options.samples_per_symbol # desired samples/symbol
48 self._fusb_block_size = options.fusb_block_size # usb info for USRP
49 self._fusb_nblocks = options.fusb_nblocks # usb info for USRP
51 self._rx_callback = rx_callback # this callback is fired when there's a packet available
52 self._demod_class = demod_class # the demodulator_class we're using
54 if self._rx_freq is None:
55 sys.stderr.write("-f FREQ or --freq FREQ or --rx-freq FREQ must be specified\n")
58 # Set up USRP source; also adjusts decim, samples_per_symbol, and bitrate
59 self._setup_usrp_source()
61 g = self.subdev.gain_range()
62 if options.show_rx_gain_range:
63 print "Rx Gain Range: minimum = %g, maximum = %g, step size = %g" \
66 self.set_gain(options.rx_gain)
68 self.set_auto_tr(True) # enable Auto Transmit/Receive switching
71 ok = self.set_freq(self._rx_freq)
73 print "Failed to set Rx frequency to %s" % (eng_notation.num_to_str(self._rx_freq))
74 raise ValueError, eng_notation.num_to_str(self._rx_freq)
76 # copy the final answers back into options for use by demodulator
77 options.samples_per_symbol = self._samples_per_symbol
78 options.bitrate = self._bitrate
79 options.decim = self._decim
82 demod_kwargs = self._demod_class.extract_kwargs_from_options(options)
84 # Design filter to get actual channel we want
86 chan_coeffs = gr.firdes.low_pass (1.0, # gain
87 sw_decim * self._samples_per_symbol, # sampling rate
88 1.0, # midpoint of trans. band
89 0.5, # width of trans. band
90 gr.firdes.WIN_HANN) # filter type
92 # Decimating channel filter
93 # complex in and out, float taps
94 self.chan_filt = gr.fft_filter_ccc(sw_decim, chan_coeffs)
95 #self.chan_filt = gr.fir_filter_ccf(sw_decim, chan_coeffs)
97 self.packet_receiver = \
98 blks2.demod_pkts(self._demod_class(**demod_kwargs),
100 callback=self._rx_callback,
103 # Carrier Sensing Blocks
105 thresh = 30 # in dB, will have to adjust
106 self.probe = gr.probe_avg_mag_sqrd_c(thresh,alpha)
108 # Display some information about the setup
110 self._print_verbage()
112 self.channel_filter = gr.fft_filter_ccc(sw_decim, chan_coeffs)
114 # connect the channel input filter to the carrier power detector
115 self.connect(self.u, self.channel_filter, self.probe)
117 # connect channel filter to the packet receiver
118 self.connect(self.channel_filter, self.packet_receiver)
121 def _setup_usrp_source(self):
122 self.u = usrp.source_c (fusb_block_size=self._fusb_block_size,
123 fusb_nblocks=self._fusb_nblocks)
124 adc_rate = self.u.adc_rate()
126 # derive values of bitrate, samples_per_symbol, and decim from desired info
127 (self._bitrate, self._samples_per_symbol, self._decim) = \
128 pick_rx_bitrate(self._bitrate, self._demod_class.bits_per_symbol(), \
129 self._samples_per_symbol, self._decim, adc_rate)
131 self.u.set_decim_rate(self._decim)
133 # determine the daughterboard subdevice we're using
134 if self._rx_subdev_spec is None:
135 self._rx_subdev_spec = usrp.pick_rx_subdevice(self.u)
136 self.subdev = usrp.selected_subdev(self.u, self._rx_subdev_spec)
138 self.u.set_mux(usrp.determine_rx_mux_value(self.u, self._rx_subdev_spec))
140 def set_freq(self, target_freq):
142 Set the center frequency we're interested in.
144 @param target_freq: frequency in Hz
147 Tuning is a two step process. First we ask the front-end to
148 tune as close to the desired frequency as it can. Then we use
149 the result of that operation and our target_frequency to
150 determine the value for the digital up converter.
152 r = self.u.tune(0, self.subdev, target_freq)
158 def set_gain(self, gain):
160 Sets the analog gain in the USRP
163 r = self.subdev.gain_range()
164 gain = (r[0] + r[1])/2 # set gain to midpoint
166 return self.subdev.set_gain(gain)
168 def set_auto_tr(self, enable):
169 return self.subdev.set_auto_tr(enable)
174 def samples_per_symbol(self):
175 return self._samples_per_symbol
180 def carrier_sensed(self):
182 Return True if we think carrier is present.
184 #return self.probe.level() > X
185 return self.probe.unmuted()
187 def carrier_threshold(self):
189 Return current setting in dB.
191 return self.probe.threshold()
193 def set_carrier_threshold(self, threshold_in_db):
195 Set carrier threshold.
197 @param threshold_in_db: set detection threshold
198 @type threshold_in_db: float (dB)
200 self.probe.set_threshold(threshold_in_db)
203 def add_options(normal, expert):
205 Adds receiver-specific options to the Options Parser
207 add_freq_option(normal)
208 if not normal.has_option("--bitrate"):
209 normal.add_option("-r", "--bitrate", type="eng_float", default=None,
210 help="specify bitrate. samples-per-symbol and interp/decim will be derived.")
211 normal.add_option("-R", "--rx-subdev-spec", type="subdev", default=None,
212 help="select USRP Rx side A or B")
213 normal.add_option("", "--rx-gain", type="eng_float", default=None, metavar="GAIN",
214 help="set receiver gain in dB [default=midpoint]. See also --show-rx-gain-range")
215 normal.add_option("", "--show-rx-gain-range", action="store_true", default=False,
216 help="print min and max Rx gain available on selected daughterboard")
217 normal.add_option("-v", "--verbose", action="store_true", default=False)
218 expert.add_option("-S", "--samples-per-symbol", type="int", default=None,
219 help="set samples/symbol [default=%default]")
220 expert.add_option("", "--rx-freq", type="eng_float", default=None,
221 help="set Rx frequency to FREQ [default=%default]", metavar="FREQ")
222 expert.add_option("-d", "--decim", type="intx", default=None,
223 help="set fpga decimation rate to DECIM [default=%default]")
224 expert.add_option("", "--log", action="store_true", default=False,
225 help="Log all parts of flow graph to files (CAUTION: lots of data)")
227 # Make a static method to call before instantiation
228 add_options = staticmethod(add_options)
231 def _print_verbage(self):
233 Prints information about the receive path
235 print "\nReceive Path:"
236 print "Using RX d'board %s" % (self.subdev.side_and_name(),)
237 print "Rx gain: %g" % (self.gain,)
238 print "modulation: %s" % (self._demod_class.__name__)
239 print "bitrate: %sb/s" % (eng_notation.num_to_str(self._bitrate))
240 print "samples/symbol: %3d" % (self._samples_per_symbol)
241 print "decim: %3d" % (self._decim)
242 print "Rx Frequency: %s" % (eng_notation.num_to_str(self._rx_freq))
244 def add_freq_option(parser):
246 Hackery that has the -f / --freq option set both tx_freq and rx_freq
248 def freq_callback(option, opt_str, value, parser):
249 parser.values.rx_freq = value
250 parser.values.tx_freq = value
252 if not parser.has_option('--freq'):
253 parser.add_option('-f', '--freq', type="eng_float",
254 action="callback", callback=freq_callback,
255 help="set Tx and/or Rx frequency to FREQ [default=%default]",