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#!/usr/bin/env python
#
# Copyright 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 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, gru, usrp, optfir, eng_notation, pager
from gnuradio.eng_option import eng_option
from optparse import OptionParser
import time, os, sys
from string import split, join
"""
This example application demonstrates receiving and demodulating the
FLEX pager protocol.
The following are required command line parameters:
-f FREQ USRP receive frequency
The following are optional command line parameters:
-R SUBDEV Daughter board specification, defaults to first found
-F FILE Read samples from a file instead of USRP.
-c FREQ Calibration offset. Gets added to receive frequency.
Defaults to 0.0 Hz.
-g GAIN Daughterboard gain setting. Defaults to mid-range.
-l Log flow graph to files (LOTS of data)
-v Verbose output
Once the program is running, ctrl-break (Ctrl-C) stops operation.
"""
class app_top_block(gr.top_block):
def __init__(self, options, queue):
gr.top_block.__init__(self, "usrp_flex")
self.options = options
self.offset = 0.0
self.adj_time = time.time()
self.verbose = options.verbose
if options.from_file is None:
# Set up USRP source with specified RX daughterboard
self.src = usrp.source_c()
if options.rx_subdev_spec == None:
options.rx_subdev_spec = usrp.pick_rx_subdevice(self.src)
self.subdev = usrp.selected_subdev(self.src, options.rx_subdev_spec)
self.src.set_mux(usrp.determine_rx_mux_value(self.src, options.rx_subdev_spec))
# Grab 250 KHz of spectrum (sample rate becomes 250 ksps complex)
self.src.set_decim_rate(256)
# If no gain specified, set to midrange
if options.gain is None:
g = self.subdev.gain_range()
options.gain = (g[0]+g[1])/2.0
self.subdev.set_gain(options.gain)
# Tune daughterboard
actual_frequency = options.frequency+options.calibration
tune_result = usrp.tune(self.src, 0, self.subdev, actual_frequency)
if not tune_result:
sys.stderr.write("Failed to set center frequency to "+`actual_frequency`+"\n")
sys.exit(1)
if options.verbose:
print "Using RX daughterboard", self.subdev.side_and_name()
print "USRP gain is", options.gain
print "USRP tuned to", actual_frequency
else:
# Use supplied file as source of samples
self.src = gr.file_source(gr.sizeof_gr_complex, options.from_file)
if options.verbose:
print "Reading samples from", options.from_file
if options.log and not options.from_file:
usrp_sink = gr.file_sink(gr.sizeof_gr_complex, 'usrp.dat')
self.connect(self.src, usrp_sink)
# Set up 22KHz-wide bandpass about center frequency. Decimate by 10
# to get channel rate of 25Ksps
taps = optfir.low_pass(1.0, # Filter gain
250e3, # Sample rate
11000, # One-sided modulation bandwidth
12500, # One-sided channel bandwidth
0.1, # Passband ripple
60) # Stopband attenuation
if options.verbose:
print "Channel filter has", len(taps), "taps."
self.chan = gr.freq_xlating_fir_filter_ccf(10, # Decimation rate
taps, # Filter taps
0.0, # Offset frequency
250e3) # Sample rate
if options.log:
chan_sink = gr.file_sink(gr.sizeof_gr_complex, 'chan.dat')
self.connect(self.chan, chan_sink)
# FLEX protocol demodulator
self.flex = pager.flex_demod(queue, options.frequency, options.verbose, options.log)
self.connect(self.src, self.chan, self.flex)
def freq_offset(self):
return self.flex.dc_offset()*1600
def adjust_freq(self):
if time.time() - self.adj_time > 1.6: # Only do it once per FLEX frame
self.adj_time = time.time()
self.offset -= self.freq_offset()
self.chan.set_center_freq(self.offset)
if self.verbose:
print "Channel frequency offset (Hz):", int(self.offset)
def main():
parser = OptionParser(option_class=eng_option)
parser.add_option("-f", "--frequency", type="eng_float", default=None,
help="set receive frequency to Hz", metavar="Hz")
parser.add_option("-R", "--rx-subdev-spec", type="subdev",
help="select USRP Rx side A or B", metavar="SUBDEV")
parser.add_option("-c", "--calibration", type="eng_float", default=0.0,
help="set frequency offset to Hz", metavar="Hz")
parser.add_option("-g", "--gain", type="int", default=None,
help="set RF gain", metavar="dB")
parser.add_option("-l", "--log", action="store_true", default=False,
help="log flowgraph to files (LOTS of data)")
parser.add_option("-v", "--verbose", action="store_true", default=False,
help="display debug output")
parser.add_option("-F", "--from-file", default=None,
help="read samples from file instead of USRP")
(options, args) = parser.parse_args()
if len(args) > 0 or (options.frequency == None and options.from_file == None):
print "Run 'usrp_flex.py -h' for options."
sys.exit(1)
if options.frequency == None:
options.frequency = 0.0
# Flow graph emits pages into message queue
queue = gr.msg_queue()
tb = app_top_block(options, queue)
runner = pager.top_block_runner(tb)
try:
while 1:
if not queue.empty_p():
msg = queue.delete_head() # Blocking read
page = join(split(msg.to_string(), chr(128)), '|')
s = pager.make_printable(page)
print s
tb.adjust_freq()
elif runner.done:
break
else:
time.sleep(1)
except KeyboardInterrupt:
tb.stop()
runner = None
if __name__ == "__main__":
main()
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