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#!/usr/bin/env python
#
# Copyright 2006,2007,2011 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, gru, uhd, optfir, audio, blks2
from gnuradio import eng_notation
from gnuradio.eng_option import eng_option
from optparse import OptionParser
import sys
"""
This example application demonstrates receiving and demodulating
different types of signals using the USRP.
A receive chain is built up of the following signal processing
blocks:
USRP - Daughter board source generating complex baseband signal.
CHAN - Low pass filter to select channel bandwidth
RFSQL - RF squelch zeroing output when input power below threshold
AGC - Automatic gain control leveling signal at [-1.0, +1.0]
DEMOD - Demodulation block appropriate to selected signal type.
This converts the complex baseband to real audio frequencies,
and applies an appropriate low pass decimating filter.
CTCSS - Optional tone squelch zeroing output when tone is not present.
RSAMP - Resampler block to convert audio sample rate to user specified
sound card output rate.
AUDIO - Audio sink for playing final output to speakers.
The following are required command line parameters:
-f FREQ USRP receive frequency
-m MOD Modulation type, select from AM, FM, or WFM
The following are optional command line parameters:
-R SUBDEV Daughter board specification, defaults to first found
-c FREQ Calibration offset. Gets added to receive frequency.
Defaults to 0.0 Hz.
-g GAIN Daughterboard gain setting. Defaults to mid-range.
-o RATE Sound card output rate. Defaults to 32000. Useful if
your sound card only accepts particular sample rates.
-r RFSQL RF squelch in db. Defaults to -50.0.
-p FREQ CTCSS frequency. Opens squelch when tone is present.
Once the program is running, ctrl-break (Ctrl-C) stops operation.
Please see fm_demod.py and am_demod.py for details of the demodulation
blocks.
"""
# (device_rate, channel_rate, audio_rate, channel_pass, channel_stop, demod)
demod_params = {
'AM' : (256e3, 16e3, 16e3, 5000, 8000, blks2.demod_10k0a3e_cf),
'FM' : (256e3, 32e3, 8e3, 8000, 9000, blks2.demod_20k0f3e_cf),
'WFM' : (320e3, 320e3, 32e3, 80000, 115000, blks2.demod_200kf3e_cf)
}
class uhd_src(gr.hier_block2):
"""
Create a UHD source object supplying complex floats.
Selects user supplied subdevice or chooses first available one.
Calibration value is the offset from the tuned frequency to
the actual frequency.
"""
def __init__(self, args, spec, antenna, samp_rate, gain=None, calibration=0.0):
gr.hier_block2.__init__(self, "uhd_src",
gr.io_signature(0, 0, 0), # Input signature
gr.io_signature(1, 1, gr.sizeof_gr_complex)) # Output signature
self._src = uhd.usrp_source(device_addr=args, stream_args=uhd.stream_args('fc32'))
# Set the subdevice spec
if(spec):
self._src.set_subdev_spec(spec, 0)
# Set the antenna
if(antenna):
self._src.set_antenna(antenna, 0)
self._src.set_samp_rate(samp_rate)
dev_rate = self._src.get_samp_rate()
self._samp_rate = samp_rate
# Resampler to get to exactly samp_rate no matter what dev_rate is
self._rrate = samp_rate / dev_rate
self._resamp = blks2.pfb_arb_resampler_ccf(self._rrate)
# If no gain specified, set to midrange
gain_range = self._src.get_gain_range()
if gain is None:
gain = (gain_range.start()+gain_range.stop())/2.0
print "Using gain: ", gain
self._src.set_gain(gain)
self._cal = calibration
self.connect(self._src, self._resamp, self)
def tune(self, freq):
r = self._src.set_center_freq(freq+self._cal, 0)
def rate(self):
return self._samp_rate
class app_top_block(gr.top_block):
def __init__(self, options):
gr.top_block.__init__(self)
self.options = options
(dev_rate, channel_rate, audio_rate,
channel_pass, channel_stop, demod) = demod_params[options.modulation]
DEV = uhd_src(options.args, # UHD device address
options.spec, # device subdev spec
options.antenna, # device antenna
dev_rate, # device sample rate
options.gain, # Receiver gain
options.calibration) # Frequency offset
DEV.tune(options.frequency)
if_rate = DEV.rate()
channel_decim = int(if_rate // channel_rate)
audio_decim = int(channel_rate // audio_rate)
CHAN_taps = optfir.low_pass(1.0, # Filter gain
if_rate, # Sample rate
channel_pass, # One sided modulation bandwidth
channel_stop, # One sided channel bandwidth
0.1, # Passband ripple
60) # Stopband attenuation
CHAN = gr.freq_xlating_fir_filter_ccf(channel_decim, # Decimation rate
CHAN_taps, # Filter taps
0.0, # Offset frequency
if_rate) # Sample rate
RFSQL = gr.pwr_squelch_cc(options.rf_squelch, # Power threshold
125.0/channel_rate, # Time constant
int(channel_rate/20), # 50ms rise/fall
False) # Zero, not gate output
AGC = gr.agc_cc(1.0/channel_rate, # Time constant
1.0, # Reference power
1.0, # Initial gain
1.0) # Maximum gain
DEMOD = demod(channel_rate, audio_decim)
# From RF to audio
#self.connect(DEV, CHAN, RFSQL, AGC, DEMOD)
self.connect(DEV, CHAN, DEMOD)
# Optionally add CTCSS and RSAMP if needed
tail = DEMOD
if options.ctcss != None and options.ctcss > 60.0:
CTCSS = gr.ctcss_squelch_ff(audio_rate, # Sample rate
options.ctcss) # Squelch tone
self.connect(DEMOD, CTCSS)
tail = CTCSS
if options.output_rate != audio_rate:
out_lcm = gru.lcm(audio_rate, options.output_rate)
out_interp = int(out_lcm // audio_rate)
out_decim = int(out_lcm // options.output_rate)
RSAMP = blks2.rational_resampler_fff(out_interp, out_decim)
self.connect(tail, RSAMP)
tail = RSAMP
# Send to audio output device
AUDIO = audio.sink(int(options.output_rate),
options.audio_output)
self.connect(tail, AUDIO)
def main():
parser = OptionParser(option_class=eng_option)
parser.add_option("-a", "--args", type="string", default="",
help="UHD device address args , [default=%default]")
parser.add_option("", "--spec", type="string", default=None,
help="Subdevice of UHD device where appropriate")
parser.add_option("-A", "--antenna", type="string", default=None,
help="select Rx Antenna where appropriate [default=%default]")
parser.add_option("-f", "--frequency", type="eng_float",
default=None, metavar="Hz",
help="set receive frequency to Hz [default=%default]")
parser.add_option("-c", "--calibration", type="eng_float",
default=0.0, metavar="Hz",
help="set frequency offset to Hz [default=%default]")
parser.add_option("-g", "--gain", type="eng_float",
metavar="dB", default=None,
help="set RF gain [default is midpoint]")
parser.add_option("-m", "--modulation", type="choice", choices=('AM','FM','WFM'),
metavar="TYPE", default=None,
help="set modulation type (AM,FM,WFM) [default=%default]")
parser.add_option("-o", "--output-rate", type="eng_float",
default=32000, metavar="RATE",
help="set audio output rate to RATE [default=%default]")
parser.add_option("-r", "--rf-squelch", type="eng_float",
default=-50.0, metavar="dB",
help="set RF squelch to dB [default=%default]")
parser.add_option("-p", "--ctcss", type="float",
default=None, metavar="FREQ",
help="set CTCSS squelch to FREQ [default=%default]")
parser.add_option("-O", "--audio-output", type="string", default="",
help="pcm device name. E.g., hw:0,0 or surround51 or /dev/dsp")
(options, args) = parser.parse_args()
if options.frequency is None:
sys.stderr.write("Must supply receive frequency with -f.\n")
sys.exit(1)
if options.modulation is None:
sys.stderr.write("Must supply a modulation type (AM, FM, WFM).\n")
sys.exit(1)
tb = app_top_block(options)
try:
tb.run()
except KeyboardInterrupt:
pass
if __name__ == "__main__":
main()
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