def __init__(self, dab_params, rx_params, verbose=False, debug=False): """ Hierarchical block for OFDM demodulation @param dab_params DAB parameter object (dab.parameters.dab_parameters) @param rx_params RX parameter object (dab.parameters.receiver_parameters) @param debug enables debug output to files @param verbose whether to produce verbose messages """ self.dp = dp = dab_params self.rp = rp = rx_params self.verbose = verbose if self.rp.softbits: gr.hier_block2.__init__(self,"ofdm_demod", gr.io_signature (1, 1, gr.sizeof_gr_complex), # input signature gr.io_signature2(2, 2, gr.sizeof_float*self.dp.num_carriers*2, gr.sizeof_char)) # output signature else: gr.hier_block2.__init__(self,"ofdm_demod", gr.io_signature (1, 1, gr.sizeof_gr_complex), # input signature gr.io_signature2(2, 2, gr.sizeof_char*self.dp.num_carriers/4, gr.sizeof_char)) # output signature # workaround for a problem that prevents connecting more than one block directly (see trac ticket #161) self.input = gr.kludge_copy(gr.sizeof_gr_complex) self.connect(self, self.input) # input filtering if self.rp.input_fft_filter: if verbose: print "--> RX filter enabled" lowpass_taps = gr.firdes_low_pass(1.0, # gain dp.sample_rate, # sampling rate rp.filt_bw, # cutoff frequency rp.filt_tb, # width of transition band gr.firdes.WIN_HAMMING) # Hamming window self.fft_filter = gr.fft_filter_ccc(1, lowpass_taps) # correct sample rate offset, if enabled if self.rp.autocorrect_sample_rate: if verbose: print "--> dynamic sample rate correction enabled" self.rate_detect_ns = detect_null.detect_null(dp.ns_length, False) self.rate_estimator = dab_swig.estimate_sample_rate_bf(dp.sample_rate, dp.frame_length) self.rate_prober = gr.probe_signal_f() self.connect(self.input, self.rate_detect_ns, self.rate_estimator, self.rate_prober) # self.resample = gr.fractional_interpolator_cc(0, 1) self.resample = dab_swig.fractional_interpolator_triggered_update_cc(0,1) self.connect(self.rate_detect_ns, (self.resample,1)) self.updater = Timer(0.1,self.update_correction) # self.updater = threading.Thread(target=self.update_correction) self.run_interpolater_update_thread = True self.updater.setDaemon(True) self.updater.start() else: self.run_interpolater_update_thread = False if self.rp.sample_rate_correction_factor != 1: if verbose: print "--> static sample rate correction enabled" self.resample = gr.fractional_interpolator_cc(0, self.rp.sample_rate_correction_factor) # timing and fine frequency synchronisation self.sync = ofdm_sync_dab2.ofdm_sync_dab(self.dp, self.rp, debug) # ofdm symbol sampler self.sampler = dab_swig.ofdm_sampler(dp.fft_length, dp.cp_length, dp.symbols_per_frame, rp.cp_gap) # fft for symbol vectors self.fft = gr.fft_vcc(dp.fft_length, True, [], True) # coarse frequency synchronisation self.cfs = dab_swig.ofdm_coarse_frequency_correct(dp.fft_length, dp.num_carriers, dp.cp_length) # diff phasor self.phase_diff = dab_swig.diff_phasor_vcc(dp.num_carriers) # remove pilot symbol self.remove_pilot = dab_swig.ofdm_remove_first_symbol_vcc(dp.num_carriers) # magnitude equalisation if self.rp.equalize_magnitude: if verbose: print "--> magnitude equalization enabled" self.equalizer = dab_swig.magnitude_equalizer_vcc(dp.num_carriers, rp.symbols_for_magnitude_equalization) # frequency deinterleaving self.deinterleave = dab_swig.frequency_interleaver_vcc(dp.frequency_deinterleaving_sequence_array) # symbol demapping self.demapper = dab_swig.qpsk_demapper_vcb(dp.num_carriers) # # connect everything # if self.rp.autocorrect_sample_rate or self.rp.sample_rate_correction_factor != 1: self.connect(self.input, self.resample) self.input2 = self.resample else: self.input2 = self.input if self.rp.input_fft_filter: self.connect(self.input2, self.fft_filter, self.sync) else: self.connect(self.input2, self.sync) # data stream self.connect((self.sync, 0), (self.sampler, 0), self.fft, (self.cfs, 0), self.phase_diff, (self.remove_pilot,0)) if self.rp.equalize_magnitude: self.connect((self.remove_pilot,0), (self.equalizer,0), self.deinterleave) else: self.connect((self.remove_pilot,0), self.deinterleave) if self.rp.softbits: if verbose: print "--> using soft bits" self.softbit_interleaver = dab_swig.complex_to_interleaved_float_vcf(self.dp.num_carriers) self.connect(self.deinterleave, self.softbit_interleaver, (self,0)) else: self.connect(self.deinterleave, self.demapper, (self,0)) # control stream self.connect((self.sync, 1), (self.sampler, 1), (self.cfs, 1), (self.remove_pilot,1)) if self.rp.equalize_magnitude: self.connect((self.remove_pilot,1), (self.equalizer,1), (self,1)) else: self.connect((self.remove_pilot,1), (self,1)) # calculate an estimate of the SNR self.phase_var_decim = gr.keep_one_in_n(gr.sizeof_gr_complex*self.dp.num_carriers, self.rp.phase_var_estimate_downsample) self.phase_var_arg = gr.complex_to_arg(dp.num_carriers) self.phase_var_v2s = gr.vector_to_stream(gr.sizeof_float, dp.num_carriers) self.phase_var_mod = dab_swig.modulo_ff(pi/2) self.phase_var_avg_mod = gr.iir_filter_ffd([rp.phase_var_estimate_alpha], [0,1-rp.phase_var_estimate_alpha]) self.phase_var_sub_avg = gr.sub_ff() self.phase_var_sqr = gr.multiply_ff() self.phase_var_avg = gr.iir_filter_ffd([rp.phase_var_estimate_alpha], [0,1-rp.phase_var_estimate_alpha]) self.probe_phase_var = gr.probe_signal_f() self.connect((self.remove_pilot,0), self.phase_var_decim, self.phase_var_arg, self.phase_var_v2s, self.phase_var_mod, (self.phase_var_sub_avg,0), (self.phase_var_sqr,0)) self.connect(self.phase_var_mod, self.phase_var_avg_mod, (self.phase_var_sub_avg,1)) self.connect(self.phase_var_sub_avg, (self.phase_var_sqr,1)) self.connect(self.phase_var_sqr, self.phase_var_avg, self.probe_phase_var) # measure processing rate self.measure_rate = dab_swig.measure_processing_rate(gr.sizeof_gr_complex, 2000000) self.connect(self.input, self.measure_rate) # debugging if debug: self.connect(self.fft, gr.file_sink(gr.sizeof_gr_complex*dp.fft_length, "debug/ofdm_after_fft.dat")) self.connect((self.cfs,0), gr.file_sink(gr.sizeof_gr_complex*dp.num_carriers, "debug/ofdm_after_cfs.dat")) self.connect(self.phase_diff, gr.file_sink(gr.sizeof_gr_complex*dp.num_carriers, "debug/ofdm_diff_phasor.dat")) self.connect((self.remove_pilot,0), gr.file_sink(gr.sizeof_gr_complex*dp.num_carriers, "debug/ofdm_pilot_removed.dat")) self.connect((self.remove_pilot,1), gr.file_sink(gr.sizeof_char, "debug/ofdm_after_cfs_trigger.dat")) self.connect(self.deinterleave, gr.file_sink(gr.sizeof_gr_complex*dp.num_carriers, "debug/ofdm_deinterleaved.dat")) if self.rp.equalize_magnitude: self.connect(self.equalizer, gr.file_sink(gr.sizeof_gr_complex*dp.num_carriers, "debug/ofdm_equalizer.dat")) if self.rp.softbits: self.connect(self.softbit_interleaver, gr.file_sink(gr.sizeof_float*dp.num_carriers*2, "debug/softbits.dat"))
def __init__(self, options, input_filename):
gr.top_block.__init__(self)
gr.enable_realtime_scheduling()
if options.real:
sizeof_input_samples = gr.sizeof_float
else:
sizeof_input_samples = gr.sizeof_gr_complex
self.src = gr.file_source(sizeof_input_samples,
input_filename,
repeat = options.loop)
self.u = generic_usrp_sink_c(interface = options.interface,
mac_addr = options.mac_addr,
subdev_spec = options.tx_subdev_spec)
print 'Using %s' % str(self.u)
print 'Possible tx frequency range: %s - %s' % \
(n2s(self.u.freq_range()[0]), n2s(self.u.freq_range()[1]))
# we need to find the closest decimation rate the USRP can handle
# to the input file's sampling rate
try:
ideal_interp = self.u.dac_rate() / options.rate
# pick the closest interpolation rate
interp = [x for x in self.u.get_interp_rates()
if x <= ideal_interp][-1]
self.u.set_interp(interp)
except IndexError:
sys.stderr.write('Failed to set USRP interpolation rate\n')
raise SystemExit, 1
output_rate = self.u.dac_rate() / interp
resamp_ratio = output_rate / options.rate
# since the input file sample rate may not be exactly what our
# output rate of the USRP (as determined by the interpolation rate),
# we need to resample our input to the output rate
num_filters = 32
cutoff = 0.99 * options.rate / 2.
transition = 0.1 * options.rate / 2.
resamp_taps = gr.firdes_low_pass(num_filters * 1.0,
num_filters * options.rate,
cutoff,
transition)
self.resamp = gr.pfb_arb_resampler_ccf(resamp_ratio,
resamp_taps,
num_filters)
if options.gain is None:
# if no gain was specified, use the mid-point in dB
g = self.u.gain_range()
options.gain = float(g[0]+g[1])/2
self.u.set_gain(options.gain)
res = self.u.set_center_freq(options.freq)
if not res:
sys.stderr.write('Failed to set frequency\n')
raise SystemExit, 1
if options.real:
# our samples are real
# we need to convert them to complex without a hilbert filter
self.hilbert = gr.hilbert_fc(64)
self.connect(self.src, self.hilbert, self.resamp, self.u)
else:
# our samples are complex
self.connect(self.src, self.resamp, self.u)
