diff options
Diffstat (limited to 'gnuradio-examples/python/usrp/usrp_spectrum_sense.py')
| -rwxr-xr-x | gnuradio-examples/python/usrp/usrp_spectrum_sense.py | 241 |
1 files changed, 241 insertions, 0 deletions
diff --git a/gnuradio-examples/python/usrp/usrp_spectrum_sense.py b/gnuradio-examples/python/usrp/usrp_spectrum_sense.py new file mode 100755 index 000000000..87768649c --- /dev/null +++ b/gnuradio-examples/python/usrp/usrp_spectrum_sense.py @@ -0,0 +1,241 @@ +#!/usr/bin/env python + +from gnuradio import gr, gru, eng_notation, optfir, window +from gnuradio import audio +from gnuradio import usrp +from gnuradio import blks +from gnuradio.eng_option import eng_option +from optparse import OptionParser +import usrp_dbid +import sys +import math +import struct + + +class tune(gr.feval_dd): + """ + This class allows C++ code to callback into python. + """ + def __init__(self, fg): + gr.feval_dd.__init__(self) + self.fg = fg + + 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.fg.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 Numarray or NumPy vector + t = msg.to_string() + self.raw_data = t + self.data = struct.unpack('%df' % (self.vlen,), t) + + +class my_graph(gr.flow_graph): + + def __init__(self): + gr.flow_graph.__init__(self) + + usage = "usage: %prog [options] min_freq max_freq" + parser = OptionParser(option_class=eng_option, usage=usage) + parser.add_option("-R", "--rx-subdev-spec", type="subdev", default=(0,0), + help="select USRP Rx side A or B (default=A)") + 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("-d", "--decim", type="intx", default=16, + help="set decimation to DECIM [default=%default]") + parser.add_option("", "--real-time", action="store_true", default=False, + help="Attempt to enable real-time scheduling") + parser.add_option("-B", "--fusb-block-size", type="int", default=0, + help="specify fast usb block size [default=%default]") + parser.add_option("-N", "--fusb-nblocks", type="int", default=0, + help="specify number of fast usb blocks [default=%default]") + + (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: + self.min_freq, self.max_freq = self.max_freq, self.min_freq # swap them + + 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" + + # If the user hasn't set the fusb_* parameters on the command line, + # pick some values that will reduce latency. + + if 1: + if options.fusb_block_size == 0 and options.fusb_nblocks == 0: + if realtime: # be more aggressive + options.fusb_block_size = gr.prefs().get_long('fusb', 'rt_block_size', 1024) + options.fusb_nblocks = gr.prefs().get_long('fusb', 'rt_nblocks', 16) + else: + options.fusb_block_size = gr.prefs().get_long('fusb', 'block_size', 4096) + options.fusb_nblocks = gr.prefs().get_long('fusb', 'nblocks', 16) + + #print "fusb_block_size =", options.fusb_block_size + #print "fusb_nblocks =", options.fusb_nblocks + + # build graph + + self.u = usrp.source_c(fusb_block_size=options.fusb_block_size, + fusb_nblocks=options.fusb_nblocks) + + + adc_rate = self.u.adc_rate() # 64 MS/s + usrp_decim = options.decim + self.u.set_decim_rate(usrp_decim) + usrp_rate = adc_rate / usrp_decim + + self.u.set_mux(usrp.determine_rx_mux_value(self.u, options.rx_subdev_spec)) + self.subdev = usrp.selected_subdev(self.u, options.rx_subdev_spec) + print "Using RX d'board %s" % (self.subdev.side_and_name(),) + + + 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 + self.max_center_freq = self.max_freq - self.freq_step/2 + + 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.subdev.gain_range() + options.gain = float(g[0]+g[1])/2 + + 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 + + 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 + + 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 down converter. + """ + return self.u.tune(0, self.subdev, target_freq) + + + def set_gain(self, gain): + self.subdev.set_gain(gain) + + +def main_loop(fg): + 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(fg.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__': + fg = my_graph() + try: + fg.start() # start executing flow graph in another thread... + main_loop(fg) + + except KeyboardInterrupt: + pass |