183 lines
6.4 KiB
Python
Executable File
183 lines
6.4 KiB
Python
Executable File
#!/usr/bin/env python
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#
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# Copyright 2009 KA1RBI
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# Copyright 2011 Steve Glass.
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#
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# This file is part of GNU Radio and part of OP25
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 3, or (at your option)
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# any later version.
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#
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# It is distributed in the hope that it will be useful, but WITHOUT
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# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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# or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
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# License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this; see the file COPYING. If not, write to
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# the Free Software Foundation, Inc., 51 Franklin Street,
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# Boston, MA 02110-1301, USA.
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#
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import math
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import sys
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import wx
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from gnuradio import audio
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from gnuradio import blks2
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from gnuradio import eng_notation
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from gnuradio import gr
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from gnuradio import gru
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from gnuradio import usrp
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from gnuradio.eng_option import eng_option
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# Python is putting the packages in some strange places
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# This is a workaround until we figure out WTF is going on
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try:
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from gnuradio import op25
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except Exception:
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import op25
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"""
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Hierarchical block for RRC-filtered P25 FM modulation.
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The input is a dibit (P25 symbol) stream (char, not packed) and the
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output is the float "C4FM" signal at baseband, suitable for
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application to an FM modulator stage
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Input is at the base symbol rate (4800), output sample rate is
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typically either 32000 (USRP TX chain) or 48000 (sound card)
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@param output_sample_rate: output sample rate
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@type output_sample_rate: integer
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"""
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class p25_mod_bf(gr.hier_block2):
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def __init__(self, output_rate):
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gr.hier_block2.__init__(self, "p25_c4fm_mod_bf",
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gr.io_signature(1, 1, gr.sizeof_char), # Input signature
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gr.io_signature(1, 1, gr.sizeof_float)) # Output signature
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symbol_rate = 4800 # P25 baseband symbol rate
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lcm = gru.lcm(symbol_rate, output_rate)
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self._interp_factor = int(lcm // symbol_rate)
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self._decimation = int(lcm // output_rate)
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self._excess_bw =0.2
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mod_map = [1.0/3.0, 1.0, -(1.0/3.0), -1.0]
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self.C2S = gr.chunks_to_symbols_bf(mod_map)
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ntaps = 11 * self._interp_factor
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rrc_taps = gr.firdes.root_raised_cosine(
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self._interp_factor, # gain (since we're interpolating by sps)
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lcm, # sampling rate
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symbol_rate,
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self._excess_bw, # excess bandwidth (roll-off factor)
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ntaps)
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self.rrc_filter = gr.interp_fir_filter_fff(self._interp_factor, rrc_taps)
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# FM pre-emphasis filter
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shaping_coeffs = [-0.018, 0.0347, 0.0164, -0.0064, -0.0344, -0.0522, -0.0398, 0.0099, 0.0798, 0.1311, 0.121, 0.0322, -0.113, -0.2499, -0.3007, -0.2137, -0.0043, 0.2825, 0.514, 0.604, 0.514, 0.2825, -0.0043, -0.2137, -0.3007, -0.2499, -0.113, 0.0322, 0.121, 0.1311, 0.0798, 0.0099, -0.0398, -0.0522, -0.0344, -0.0064, 0.0164, 0.0347, -0.018]
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self.shaping_filter = gr.fir_filter_fff(1, shaping_coeffs)
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# generate output at appropriate rate
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self.decimator = blks2.rational_resampler_fff(1, self._decimation)
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self.connect(self, self.C2S, self.rrc_filter, self.shaping_filter, self.decimator, self)
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def forecast(noutput, ninput_reqd):
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ninput_reqd[0] = noutput * 26.7
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"""
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Simple tx-from-pcap-file utility.
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"""
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class usrp_c4fm_tx_block(gr.top_block):
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def __init__(self, subdev_spec, freq, subdev_gain, filename, delay):
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gr.top_block.__init__ (self)
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# data sink and sink rate
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u = usrp.sink_c()
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# important vars (to be calculated from USRP when available
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dac_rate = u.dac_rate()
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usrp_rate = 320e3
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usrp_interp = int(dac_rate // usrp_rate)
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channel_rate = 32e3
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interp_factor = int(usrp_rate // channel_rate)
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# open the pcap source
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pcap = op25.pcap_source_b(filename, delay)
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# pcap = gr.glfsr_source_b(16)
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# convert octets into dibits
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bits_per_symbol = 2
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unpack = gr.packed_to_unpacked_bb(bits_per_symbol, gr.GR_MSB_FIRST)
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# modulator
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c4fm = p25_mod_bf(output_rate=channel_rate)
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# setup low pass filter + interpolator
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low_pass = 2.88e3
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interp_taps = gr.firdes.low_pass(1.0, channel_rate, low_pass, low_pass * 0.1, gr.firdes.WIN_HANN)
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interpolator = gr.interp_fir_filter_fff (int(interp_factor), interp_taps)
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# frequency modulator
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max_dev = 12.5e3
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k = 2 * math.pi * max_dev / usrp_rate
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adjustment = 1.5 # adjust for proper c4fm deviation level
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fm = gr.frequency_modulator_fc(k * adjustment)
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# signal gain
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gain = gr.multiply_const_cc(4000)
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# configure USRP
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if subdev_spec is None:
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subdev_spec = usrp.pick_tx_subdevice(u)
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u.set_mux(usrp.determine_tx_mux_value(u, subdev_spec))
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self.db = usrp.selected_subdev(u, subdev_spec)
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print "Using TX d'board %s" % (self.db.side_and_name(),)
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u.set_interp_rate(usrp_interp)
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if gain is None:
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g = self.db.gain_range()
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gain = float(g[0] + g[1]) / 2
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self.db.set_gain(self.db.gain_range()[0])
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u.tune(self.db.which(), self.db, freq)
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self.db.set_enable(True)
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self.connect(pcap, unpack, c4fm, interpolator, fm, gain, u)
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# inject frames
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#
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if __name__ == '__main__':
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from optparse import OptionParser
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parser = OptionParser (option_class=eng_option)
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parser.add_option("-T", "--subdev-spec", type="subdev", default=None,
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help="select USRP Tx side A or B")
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parser.add_option("-f", "--freq", type="eng_float", default=None,
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help="set Tx frequency to FREQ [required]")
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parser.add_option("-g", "--gain", type="eng_float", default=None,
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help="set device gain")
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parser.add_option("-p", "--pcap-file", default="",
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help="packet capture file [required]")
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parser.add_option("-d", "--delay", type="int", default=0,
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help="delay before TX of first symbol [default=%default]")
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(options, args) = parser.parse_args ()
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if options.freq is None:
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parser.print_help()
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sys.exit(1)
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try:
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rx = usrp_c4fm_tx_block(options.subdev_spec, options.freq, options.gain, options.pcap_file, options.delay)
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rx.run()
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except KeyboardInterrupt:
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rx.db.set_enable(False)
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