usrp_psr_receiver.py

这是用python语言写的一个数字广播的信号处理工具包。利用它

#!/usr/bin/env python
#
# Copyright 2004,2005 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.
# 


#
#
# Pulsar receiver application
#
# Performs both harmonic folding analysis
#  and epoch folding analysis
#
#
from gnuradio import gr, gru, blks, audio
from usrpm import usrp_dbid
from gnuradio import usrp, optfir
from gnuradio import eng_notation
from gnuradio.eng_option import eng_option
from gnuradio.wxgui import stdgui, ra_fftsink, ra_stripchartsink, form, slider
from optparse import OptionParser
import wx
import sys
import Numeric
import FFT
import ephem
import time
import os
import math


class app_flow_graph(stdgui.gui_flow_graph):
    def __init__(self, frame, panel, vbox, argv):
        stdgui.gui_flow_graph.__init__(self)

        self.frame = frame
        self.panel = panel
        
        parser = OptionParser(option_class=eng_option)
        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("-d", "--decim", type="int", default=16,
                          help="set fgpa decimation rate to DECIM [default=%default]")
        parser.add_option("-f", "--freq", type="eng_float", default=None,
                          help="set frequency to FREQ", metavar="FREQ")
        parser.add_option("-Q", "--observing", type="eng_float", default=0.0,
                          help="set observing frequency to FREQ")
        parser.add_option("-a", "--avg", type="eng_float", default=1.0,
		help="set spectral averaging alpha")
        parser.add_option("-V", "--favg", type="eng_float", default=2.0,
                help="set folder averaging alpha")
        parser.add_option("-g", "--gain", type="eng_float", default=None,
                          help="set gain in dB (default is midpoint)")
        parser.add_option("-l", "--reflevel", type="eng_float", default=30.0,
                          help="Set pulse display reference level")
        parser.add_option("-L", "--lowest", type="eng_float", default=1.5,
                          help="Lowest valid frequency bin")
        parser.add_option("-e", "--longitude", type="eng_float", default=-76.02,                          help="Set Observer Longitude")
        parser.add_option("-c", "--latitude", type="eng_float", default=44.85,                          help="Set Observer Latitude")
        parser.add_option("-F", "--fft_size", type="eng_float", default=1024, help="Size of FFT")

        parser.add_option ("-t", "--threshold", type="eng_float", default=2.5, help="pulsar threshold")
        parser.add_option("-p", "--lowpass", type="eng_float", default=100, help="Pulse spectra cutoff freq")
        parser.add_option("-P", "--prefix", default="./", help="File prefix")
        parser.add_option("-u", "--pulsefreq", type="eng_float", default=0.748, help="Observation pulse rate")
        parser.add_option("-D", "--dm", type="eng_float", default=1.0e-5, help="Dispersion Measure")
        parser.add_option("-O", "--doppler", type="eng_float", default=1.0, help="Doppler ratio")
        parser.add_option("-B", "--divbase", type="eng_float", default=20, help="Y/Div menu base")
        parser.add_option("-I", "--division", type="eng_float", default=100, help="Y/Div")
        parser.add_option("-A", "--audio_source", default="plughw:0,0", help="Audio input device spec")
        (options, args) = parser.parse_args()
        if len(args) != 0:
            parser.print_help()
            sys.exit(1)

        self.show_debug_info = True

        self.reflevel = options.reflevel
        self.divbase = options.divbase
        self.division = options.division
        self.audiodev = options.audio_source

        # Low-pass cutoff for post-detector filter
        # Set to 100Hz usually, since lots of pulsars fit in this
        #   range
        self.lowpass = options.lowpass

        # What is lowest valid frequency bin in post-detector FFT?
        # There's some pollution very close to DC
        self.lowest_freq = options.lowest

        # What (dB) threshold to use in determining spectral candidates
        self.threshold = options.threshold

        # Filename prefix for recording file
        self.prefix = options.prefix

        # Dispersion Measure (DM)
        self.dm = options.dm

        # Doppler shift, as a ratio
        #  1.0 == no doppler shift
        #  1.005 == a little negative shift
        #  0.995 == a little positive shift
        self.doppler = options.doppler

        #
        # Input frequency and observing frequency--not necessarily the
        #   same thing, if we're looking at the IF of some downconverter
        #   that's ahead of the USRP and daughtercard.  This distinction
        #   is important in computing the correct de-dispersion filter.
        #
        self.frequency = options.freq
        if options.observing <= 0:
            self.observing_freq = options.freq
        else:
            self.observing_freq = options.observing
        
        # build the graph
        self.u = usrp.source_c(decim_rate=options.decim)
        self.u.set_mux(usrp.determine_rx_mux_value(self.u, options.rx_subdev_spec))

        #
        # Recording file, in case we ever need to record baseband data
        #
        self.recording = gr.file_sink(gr.sizeof_char, "/dev/null")
        self.recording_state = False

        self.pulse_recording = gr.file_sink(gr.sizeof_short, "/dev/null")
        self.pulse_recording_state = False

        #
        # We come up with recording turned off, but the user may
        #  request recording later on
        self.recording.close()
        self.pulse_recording.close()

        #
        # Need these two for converting 12-bit baseband signals to 8-bit
        #
        self.tofloat = gr.complex_to_float()
        self.tochar = gr.float_to_char()

        # Need this for recording pulses (post-detector)
        self.toshort = gr.float_to_short()


        #
        # The spectral measurer sets this when it has a valid
        #   average spectral peak-to-peak distance
        # We can then use this to program the parameters for the epoch folder
        #
        # We set a sentimental value here
        self.pulse_freq = options.pulsefreq

        # Folder runs at this raw sample rate
        self.folder_input_rate = 20000

        # Each pulse in the epoch folder is sampled at 128 times the nominal
        #  pulse rate
        self.folding = 128

 
        #
        # Try to find candidate parameters for rational resampler
        #
        save_i = 0
        candidates = []
        for i in range(20,300):
            input_rate = self.folder_input_rate
            output_rate = int(self.pulse_freq * i)
            interp = gru.lcm(input_rate, output_rate) / input_rate
            decim = gru.lcm(input_rate, output_rate) / output_rate
            if (interp < 500 and decim < 250000):
                 candidates.append(i)

        # We didn't find anything, bail!
        if (len(candidates) < 1):
            print "Couldn't converge on resampler parameters"
            sys.exit(1)

        #
        # Now try to find candidate with the least sampling error
        #
        mindiff = 999.999
        for i in candidates:
            diff = self.pulse_freq * i
            diff = diff - int(diff)
            if (diff < mindiff):
                mindiff = diff
                save_i = i

        # Recompute rates
        input_rate = self.folder_input_rate
        output_rate = int(self.pulse_freq * save_i)

        # Compute new interp and decim, based on best candidate
        interp = gru.lcm(input_rate, output_rate) / input_rate
        decim = gru.lcm(input_rate, output_rate) / output_rate

        # Save optimized folding parameters, used later
        self.folding = save_i
        self.interp = int(interp)
        self.decim = int(decim)

        # So that we can view 4 pulses in the pulse viewer window
        FOLD_MULT=1

        # determine the daughterboard subdevice we're using
        self.subdev = usrp.selected_subdev(self.u, options.rx_subdev_spec)
        self.cardtype = self.u.daughterboard_id(0)

        # Compute raw input rate
        input_rate = self.u.adc_freq() / self.u.decim_rate()

        # BW==input_rate for complex data
        self.bw = input_rate

        #
        # Set baseband filter bandwidth if DBS_RX:
        #
        if self.cardtype == usrp_dbid.DBS_RX:
            lbw = input_rate / 2
            if lbw < 1.0e6:
                lbw = 1.0e6
            self.subdev.set_bw(lbw)

        #
        # We use this as a crude volume control for the audio output
        #
        self.volume = gr.multiply_const_ff(10**(-1))
        

        #
        # Create location data for ephem package
        #
        self.locality = ephem.Observer()
        self.locality.long = str(options.longitude)
        self.locality.lat = str(options.latitude)

        #
        # What is the post-detector LPF cutoff for the FFT?
        #
        PULSAR_MAX_FREQ=int(options.lowpass)

        # First low-pass filters down to input_rate/FIRST_FACTOR
        #   and decimates appropriately
        FIRST_FACTOR=int(input_rate/(self.folder_input_rate/2))
        first_filter = gr.firdes.low_pass (1.0,
                                          input_rate,
                                          input_rate/FIRST_FACTOR,
                                          input_rate/(FIRST_FACTOR*20),         
                                          gr.firdes.WIN_HAMMING)

        # Second filter runs at the output rate of the first filter,
        #  And low-pass filters down to PULSAR_MAX_FREQ*10
        #
        second_input_rate =  int(input_rate/(FIRST_FACTOR/2))
        second_filter = gr.firdes.band_pass(1.0, second_input_rate,
                                          0.10,
                                          PULSAR_MAX_FREQ*10,
                                          PULSAR_MAX_FREQ*1.5,
                                          gr.firdes.WIN_HAMMING)

        # Third filter runs at PULSAR_MAX_FREQ*20
        #   and filters down to PULSAR_MAX_FREQ
        #
        third_input_rate = PULSAR_MAX_FREQ*20
        third_filter = gr.firdes_band_pass(1.0, third_input_rate,
                                           0.10, PULSAR_MAX_FREQ,
                                           PULSAR_MAX_FREQ/10.0,
                                           gr.firdes.WIN_HAMMING)


        #
        # Create the appropriate FFT scope
        #
        self.scope = ra_fftsink.ra_fft_sink_f (self, panel, 
           fft_size=int(options.fft_size), sample_rate=PULSAR_MAX_FREQ*2,
           title="Post-detector spectrum",  
           ofunc=self.pulsarfunc, xydfunc=self.xydfunc, fft_rate=200)

        #
        # Tell scope we're looking from DC to PULSAR_MAX_FREQ
        #
        self.scope.set_baseband_freq (0.0)


        #
        # Setup stripchart for showing pulse profiles
        #
        hz = "%5.3fHz " % self.pulse_freq
        per = "(%5.3f sec)" % (1.0/self.pulse_freq)
        sr = "%d sps" % (int(self.pulse_freq*self.folding))
        self.chart = ra_stripchartsink.stripchart_sink_f (self, panel,
               sample_rate=1,
               stripsize=self.folding*FOLD_MULT, parallel=True, title="Pulse Profiles: "+hz+per, 
               xlabel="Seconds @ "+sr, ylabel="Level", autoscale=True,
               divbase=self.divbase, scaling=1.0/(self.folding*self.pulse_freq))
        self.chart.set_ref_level(self.reflevel)
        self.chart.set_y_per_div(self.division)

        # De-dispersion filter setup
        #
        # Do this here, just before creating the filter
        #  that will use the taps.
        #
        ntaps = self.compute_disp_ntaps(self.dm,self.bw,self.observing_freq)

        # Taps for the de-dispersion filter
        self.disp_taps = Numeric.zeros(ntaps,Numeric.Complex64)

        # Compute the de-dispersion filter now
        self.compute_dispfilter(self.dm,self.doppler,
            self.bw,self.observing_freq)

        #
        # Call constructors for receive chains
        #

        #
        # Now create the FFT filter using the computed taps
        self.dispfilt = gr.fft_filter_ccc(1, self.disp_taps)

        #
        # Audio sink
        #
        self.audio = audio.sink(second_input_rate, self.audiodev)

        #
        # The three post-detector filters
        # Done this way to allow an audio path (up to 10Khz)
        # ...and also because going from xMhz down to ~100Hz
        # In a single filter doesn't seem to work.
        #
        self.first = gr.fir_filter_fff (FIRST_FACTOR/2, first_filter)

        p = second_input_rate / (PULSAR_MAX_FREQ*20)
        self.second = gr.fir_filter_fff (int(p), second_filter)
        self.third = gr.fir_filter_fff (10, third_filter)

        # Detector
        self.detector = gr.complex_to_mag_squared()

        self.enable_comb_filter = False
        # Epoch folder comb filter
        if self.enable_comb_filter == True:
            bogtaps = Numeric.zeros(512, Numeric.Float64)