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#!/usr/bin/env python
#
# Copyright 2005,2007,2011 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 3, 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, eng_notation, window
from gnuradio import audio
from gnuradio import uhd
from gnuradio.eng_option import eng_option
from optparse import OptionParser
import sys
import math
import struct
sys.stderr.write("Warning: this is known to have issues on some machines+Python version combinations to seg fault due to the callback in bin_statitics. If you figure out why, we'd love to hear about it!\n")
class tune(gr.feval_dd):
"""
This class allows C++ code to callback into python.
"""
def __init__(self, tb):
gr.feval_dd.__init__(self)
self.tb = tb
def eval(self, ignore):
"""
This method is called from gr.bin_statistics_f when it wants
to change the center frequency. This method tunes the front
end to the new center frequency, and returns the new frequency
as its result.
"""
try:
# We use this try block so that if something goes wrong
# from here down, at least we'll have a prayer of knowing
# what went wrong. Without this, you get a very
# mysterious:
#
# terminate called after throwing an instance of
# 'Swig::DirectorMethodException' Aborted
#
# message on stderr. Not exactly helpful ;)
new_freq = self.tb.set_next_freq()
return new_freq
except Exception, e:
print "tune: Exception: ", e
class parse_msg(object):
def __init__(self, msg):
self.center_freq = msg.arg1()
self.vlen = int(msg.arg2())
assert(msg.length() == self.vlen * gr.sizeof_float)
# FIXME consider using NumPy array
t = msg.to_string()
self.raw_data = t
self.data = struct.unpack('%df' % (self.vlen,), t)
class my_top_block(gr.top_block):
def __init__(self):
gr.top_block.__init__(self)
usage = "usage: %prog [options] min_freq max_freq"
parser = OptionParser(option_class=eng_option, usage=usage)
parser.add_option("-a", "--args", type="string", default="",
help="UHD device device address args [default=%default]")
parser.add_option("-A", "--antenna", type="string", default=None,
help="select Rx Antenna where appropriate")
parser.add_option("-s", "--samp-rate", type="eng_float", default=1e6,
help="set sample rate [default=%default]")
parser.add_option("-g", "--gain", type="eng_float", default=None,
help="set gain in dB (default is midpoint)")
parser.add_option("", "--tune-delay", type="eng_float",
default=1e-3, metavar="SECS",
help="time to delay (in seconds) after changing frequency [default=%default]")
parser.add_option("", "--dwell-delay", type="eng_float",
default=10e-3, metavar="SECS",
help="time to dwell (in seconds) at a given frequncy [default=%default]")
parser.add_option("-F", "--fft-size", type="int", default=256,
help="specify number of FFT bins [default=%default]")
parser.add_option("", "--real-time", action="store_true", default=False,
help="Attempt to enable real-time scheduling")
(options, args) = parser.parse_args()
if len(args) != 2:
parser.print_help()
sys.exit(1)
self.min_freq = eng_notation.str_to_num(args[0])
self.max_freq = eng_notation.str_to_num(args[1])
if self.min_freq > self.max_freq:
# swap them
self.min_freq, self.max_freq = self.max_freq, self.min_freq
self.fft_size = options.fft_size
if not options.real_time:
realtime = False
else:
# Attempt to enable realtime scheduling
r = gr.enable_realtime_scheduling()
if r == gr.RT_OK:
realtime = True
else:
realtime = False
print "Note: failed to enable realtime scheduling"
# build graph
self.u = uhd.usrp_source(device_addr=options.args,
io_type=uhd.io_type.COMPLEX_FLOAT32,
num_channels=1)
usrp_rate = options.samp_rate
self.u.set_samp_rate(usrp_rate)
dev_rate = self.u.get_samp_rate()
s2v = gr.stream_to_vector(gr.sizeof_gr_complex, self.fft_size)
mywindow = window.blackmanharris(self.fft_size)
fft = gr.fft_vcc(self.fft_size, True, mywindow)
power = 0
for tap in mywindow:
power += tap*tap
c2mag = gr.complex_to_mag_squared(self.fft_size)
# FIXME the log10 primitive is dog slow
log = gr.nlog10_ff(10, self.fft_size,
-20*math.log10(self.fft_size)-10*math.log10(power/self.fft_size))
# Set the freq_step to 75% of the actual data throughput.
# This allows us to discard the bins on both ends of the spectrum.
self.freq_step = 0.75 * usrp_rate
self.min_center_freq = self.min_freq + self.freq_step/2
nsteps = math.ceil((self.max_freq - self.min_freq) / self.freq_step)
self.max_center_freq = self.min_center_freq + (nsteps * self.freq_step)
self.next_freq = self.min_center_freq
tune_delay = max(0, int(round(options.tune_delay * usrp_rate / self.fft_size))) # in fft_frames
dwell_delay = max(1, int(round(options.dwell_delay * usrp_rate / self.fft_size))) # in fft_frames
self.msgq = gr.msg_queue(16)
self._tune_callback = tune(self) # hang on to this to keep it from being GC'd
stats = gr.bin_statistics_f(self.fft_size, self.msgq,
self._tune_callback, tune_delay,
dwell_delay)
# FIXME leave out the log10 until we speed it up
#self.connect(self.u, s2v, fft, c2mag, log, stats)
self.connect(self.u, s2v, fft, c2mag, stats)
if options.gain is None:
# if no gain was specified, use the mid-point in dB
g = self.u.get_gain_range()
options.gain = float(g.start()+g.stop())/2.0
self.set_gain(options.gain)
print "gain =", options.gain
def set_next_freq(self):
target_freq = self.next_freq
self.next_freq = self.next_freq + self.freq_step
if self.next_freq >= self.max_center_freq:
self.next_freq = self.min_center_freq
if not self.set_freq(target_freq):
print "Failed to set frequency to", target_freq
sys.exit(1)
return target_freq
def set_freq(self, target_freq):
"""
Set the center frequency we're interested in.
@param target_freq: frequency in Hz
@rypte: bool
"""
r = self.u.set_center_freq(target_freq)
if r:
return True
return False
def set_gain(self, gain):
self.u.set_gain(gain)
def main_loop(tb):
while 1:
# Get the next message sent from the C++ code (blocking call).
# It contains the center frequency and the mag squared of the fft
m = parse_msg(tb.msgq.delete_head())
# Print center freq so we know that something is happening...
print m.center_freq
# FIXME do something useful with the data...
# m.data are the mag_squared of the fft output (they are in the
# standard order. I.e., bin 0 == DC.)
# You'll probably want to do the equivalent of "fftshift" on them
# m.raw_data is a string that contains the binary floats.
# You could write this as binary to a file.
if __name__ == '__main__':
tb = my_top_block()
try:
tb.start()
main_loop(tb)
except KeyboardInterrupt:
pass
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