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#
# Copyright 2005,2006,2007 Free Software Foundation, Inc.
#
# This file is part of GNU Radio
#
# GNU Radio is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2, or (at your option)
# any later version.
#
# GNU Radio is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with GNU Radio; see the file COPYING. If not, write to
# the Free Software Foundation, Inc., 51 Franklin Street,
# Boston, MA 02110-1301, USA.
#
from gnuradio import gr, gru, blks2
from gnuradio import usrp
from gnuradio import eng_notation
import copy
import sys
# from current dir
from pick_bitrate import pick_tx_bitrate
# /////////////////////////////////////////////////////////////////////////////
# transmit path
# /////////////////////////////////////////////////////////////////////////////
class transmit_path(gr.top_block):
def __init__(self, modulator_class, options):
'''
See below for what options should hold
'''
gr.top_block.__init__(self, "transmit_path")
options = copy.copy(options) # make a copy so we can destructively modify
self._verbose = options.verbose
self._tx_freq = options.tx_freq # tranmitter's center frequency
self._tx_amplitude = options.tx_amplitude # digital amplitude sent to USRP
self._tx_subdev_spec = options.tx_subdev_spec # daughterboard to use
self._bitrate = options.bitrate # desired bit rate
self._interp = options.interp # interpolating rate for the USRP (prelim)
self._samples_per_symbol = options.samples_per_symbol # desired samples/baud
self._fusb_block_size = options.fusb_block_size # usb info for USRP
self._fusb_nblocks = options.fusb_nblocks # usb info for USRP
self._modulator_class = modulator_class # the modulator_class we are using
if self._tx_freq is None:
sys.stderr.write("-f FREQ or --freq FREQ or --tx-freq FREQ must be specified\n")
raise SystemExit
# Set up USRP sink; also adjusts interp, samples_per_symbol, and bitrate
self._setup_usrp_sink()
# copy the final answers back into options for use by modulator
options.samples_per_symbol = self._samples_per_symbol
options.bitrate = self._bitrate
options.interp = self._interp
# Get mod_kwargs
mod_kwargs = self._modulator_class.extract_kwargs_from_options(options)
# Set center frequency of USRP
ok = self.set_freq(self._tx_freq)
if not ok:
print "Failed to set Tx frequency to %s" % (eng_notation.num_to_str(self._tx_freq),)
raise ValueError
# transmitter
self.packet_transmitter = \
blks2.mod_pkts(self._modulator_class(**mod_kwargs),
access_code=None,
msgq_limit=4,
pad_for_usrp=True)
# Set the USRP for maximum transmit gain
# (Note that on the RFX cards this is a nop.)
self.set_gain(self.subdev.gain_range()[0])
self.amp = gr.multiply_const_cc(1)
self.set_tx_amplitude(self._tx_amplitude)
# enable Auto Transmit/Receive switching
self.set_auto_tr(True)
# Display some information about the setup
if self._verbose:
self._print_verbage()
self.connect(self.packet_transmitter, self.amp, self.u)
def _setup_usrp_sink(self):
"""
Creates a USRP sink, determines the settings for best bitrate,
and attaches to the transmitter's subdevice.
"""
self.u = usrp.sink_c(fusb_block_size=self._fusb_block_size,
fusb_nblocks=self._fusb_nblocks)
dac_rate = self.u.dac_rate();
# derive values of bitrate, samples_per_symbol, and interp from desired info
(self._bitrate, self._samples_per_symbol, self._interp) = \
pick_tx_bitrate(self._bitrate, self._modulator_class.bits_per_symbol(),
self._samples_per_symbol, self._interp, dac_rate)
self.u.set_interp_rate(self._interp)
# determine the daughterboard subdevice we're using
if self._tx_subdev_spec is None:
self._tx_subdev_spec = usrp.pick_tx_subdevice(self.u)
self.u.set_mux(usrp.determine_tx_mux_value(self.u, self._tx_subdev_spec))
self.subdev = usrp.selected_subdev(self.u, self._tx_subdev_spec)
def set_freq(self, target_freq):
"""
Set the center frequency we're interested in.
@param target_freq: frequency in Hz
@rypte: bool
Tuning is a two step process. First we ask the front-end to
tune as close to the desired frequency as it can. Then we use
the result of that operation and our target_frequency to
determine the value for the digital up converter.
"""
r = self.u.tune(self.subdev._which, self.subdev, target_freq)
if r:
return True
return False
def set_gain(self, gain):
"""
Sets the analog gain in the USRP
"""
self.gain = gain
self.subdev.set_gain(gain)
def set_tx_amplitude(self, ampl):
"""
Sets the transmit amplitude sent to the USRP
@param: ampl 0 <= ampl < 32768. Try 8000
"""
self._tx_amplitude = max(0.0, min(ampl, 32767.0))
self.amp.set_k(self._tx_amplitude)
def set_auto_tr(self, enable):
"""
Turns on auto transmit/receive of USRP daughterboard (if exits; else ignored)
"""
return self.subdev.set_auto_tr(enable)
def send_pkt(self, payload='', eof=False):
"""
Calls the transmitter method to send a packet
"""
return self.packet_transmitter.send_pkt(payload, eof)
def bitrate(self):
return self._bitrate
def samples_per_symbol(self):
return self._samples_per_symbol
def interp(self):
return self._interp
def add_options(normal, expert):
"""
Adds transmitter-specific options to the Options Parser
"""
add_freq_option(normal)
if not normal.has_option('--bitrate'):
normal.add_option("-r", "--bitrate", type="eng_float", default=None,
help="specify bitrate. samples-per-symbol and interp/decim will be derived.")
normal.add_option("-T", "--tx-subdev-spec", type="subdev", default=None,
help="select USRP Tx side A or B")
normal.add_option("", "--tx-amplitude", type="eng_float", default=12000, metavar="AMPL",
help="set transmitter digital amplitude: 0 <= AMPL < 32768 [default=%default]")
normal.add_option("-v", "--verbose", action="store_true", default=False)
expert.add_option("-S", "--samples-per-symbol", type="int", default=None,
help="set samples/symbol [default=%default]")
expert.add_option("", "--tx-freq", type="eng_float", default=None,
help="set transmit frequency to FREQ [default=%default]", metavar="FREQ")
expert.add_option("-i", "--interp", type="intx", default=None,
help="set fpga interpolation rate to INTERP [default=%default]")
expert.add_option("", "--log", action="store_true", default=False,
help="Log all parts of flow graph to file (CAUTION: lots of data)")
# Make a static method to call before instantiation
add_options = staticmethod(add_options)
def _print_verbage(self):
"""
Prints information about the transmit path
"""
print "Using TX d'board %s" % (self.subdev.side_and_name(),)
print "Tx amplitude %s" % (self._tx_amplitude)
print "modulation: %s" % (self._modulator_class.__name__)
print "bitrate: %sb/s" % (eng_notation.num_to_str(self._bitrate))
print "samples/symbol: %3d" % (self._samples_per_symbol)
print "interp: %3d" % (self._interp)
print "Tx Frequency: %s" % (eng_notation.num_to_str(self._tx_freq))
def add_freq_option(parser):
"""
Hackery that has the -f / --freq option set both tx_freq and rx_freq
"""
def freq_callback(option, opt_str, value, parser):
parser.values.rx_freq = value
parser.values.tx_freq = value
if not parser.has_option('--freq'):
parser.add_option('-f', '--freq', type="eng_float",
action="callback", callback=freq_callback,
help="set Tx and/or Rx frequency to FREQ [default=%default]",
metavar="FREQ")
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