#!/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()