def __init__(self, dab_params, rx_params, debug=False): """ OFDM time and coarse frequency synchronisation for DAB @param mode DAB mode (1-4) @param debug if True: write data streams out to files """ dp = dab_params rp = rx_params gr.hier_block2.__init__(self,"ofdm_sync_dab", gr.io_signature(1, 1, gr.sizeof_gr_complex), # input signature gr.io_signature2(2, 2, gr.sizeof_gr_complex, 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) # # null-symbol detection # # (outsourced to detect_zero.py) self.ns_detect = detect_null.detect_null(dp.ns_length, debug) self.connect(self.input, self.ns_detect) # # fine frequency synchronisation # # the code for fine frequency synchronisation is adapted from # ofdm_sync_ml.py; it abuses the cyclic prefix to find the fine # frequency error, as suggested in "ML Estimation of Timing and # Frequency Offset in OFDM Systems", by Jan-Jaap van de Beek, # Magnus Sandell, Per Ola Börjesson, see # http://www.sm.luth.se/csee/sp/research/report/bsb96r.html self.ffs_delay = gr.delay(gr.sizeof_gr_complex, dp.fft_length) self.ffs_conj = gr.conjugate_cc() self.ffs_mult = gr.multiply_cc() self.ffs_moving_sum = dab_swig.moving_sum_cc(dp.cp_length) self.ffs_arg = gr.complex_to_arg() self.ffs_sample_and_average = dab_swig.ofdm_ffs_sample(dp.symbol_length, dp.fft_length, rp.symbols_for_ffs_estimation, rp.ffs_alpha, dp.sample_rate) if rp.correct_ffe: self.ffs_delay_input_for_correction = gr.delay(gr.sizeof_gr_complex, dp.symbol_length*rp.symbols_for_ffs_estimation) # by delaying the input, we can use the ff offset estimation from the first symbol to correct the first symbol itself self.ffs_delay_frame_start = gr.delay(gr.sizeof_char, dp.symbol_length*rp.symbols_for_ffs_estimation) # sample the value at the end of the symbol .. self.ffs_nco = gr.frequency_modulator_fc(1) # ffs_sample_and_hold directly outputs phase error per sample self.ffs_mixer = gr.multiply_cc() # calculate fine frequency error self.connect(self.input, self.ffs_conj, self.ffs_mult) self.connect(self.input, self.ffs_delay, (self.ffs_mult, 1)) self.connect(self.ffs_mult, self.ffs_moving_sum, self.ffs_arg, (self.ffs_sample_and_average, 0)) self.connect(self.ns_detect, (self.ffs_sample_and_average, 1)) if rp.correct_ffe: # do the correction self.connect(self.ffs_sample_and_average, self.ffs_nco, (self.ffs_mixer, 0)) self.connect(self.input, self.ffs_delay_input_for_correction, (self.ffs_mixer, 1)) # output - corrected signal and start of DAB frames self.connect(self.ffs_mixer, (self, 0)) self.connect(self.ns_detect, self.ffs_delay_frame_start, (self, 1)) else: # just patch the signal through self.connect(self.ffs_sample_and_average, gr.null_sink(gr.sizeof_float)) self.connect(self.input, (self,0)) # frame start still needed .. self.connect(self.ns_detect, (self,1)) if debug: self.connect(self.ffs_sample_and_average, gr.multiply_const_ff(1./(dp.T*2*pi)), gr.file_sink(gr.sizeof_float, "debug/ofdm_sync_dab_fine_freq_err_f.dat")) self.connect(self.ffs_mixer, gr.file_sink(gr.sizeof_gr_complex, "debug/ofdm_sync_dab_fine_freq_corrected_c.dat"))
def __init__(self, mode, debug=False):
"""
OFDM time and coarse frequency synchronisation for DAB
@param mode DAB mode (1-4)
@param debug if True: write data streams out to files
"""
if mode < 1 or mode > 4:
raise ValueError, "Invalid DAB mode: " + str(
mode) + " (modes 1-4 exist)"
# get the correct DAB parameters
dp = parameters.dab_parameters(mode)
rp = parameters.receiver_parameters(mode)
gr.hier_block2.__init__(
self,
"ofdm_sync_dab",
gr.io_signature(1, 1, gr.sizeof_gr_complex), # input signature
gr.io_signature2(2, 2, gr.sizeof_gr_complex,
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)
#
# null-symbol detection
#
# (outsourced to detect_zero.py)
self.ns_detect = detect_null.detect_null(dp.ns_length, debug)
self.connect(self.input, self.ns_detect)
#
# fine frequency synchronisation
#
# the code for fine frequency synchronisation is adapted from
# ofdm_sync_ml.py; it abuses the cyclic prefix to find the fine
# frequency error, as suggested in "ML Estimation of Timing and
# Frequency Offset in OFDM Systems", by Jan-Jaap van de Beek,
# Magnus Sandell, Per Ola Börjesson, see
# http://www.sm.luth.se/csee/sp/research/report/bsb96r.html
self.ffs_delay = gr.delay(gr.sizeof_gr_complex, dp.fft_length)
self.ffs_conj = gr.conjugate_cc()
self.ffs_mult = gr.multiply_cc()
# self.ffs_moving_sum = gr.fir_filter_ccf(1, [1]*dp.cp_length)
self.ffs_moving_sum = dab_swig.moving_sum_cc(dp.cp_length)
self.ffs_angle = gr.complex_to_arg()
self.ffs_angle_scale = gr.multiply_const_ff(1. / dp.fft_length)
self.ffs_delay_sample_and_hold = gr.delay(
gr.sizeof_char,
dp.symbol_length) # sample the value at the end of the symbol ..
self.ffs_sample_and_hold = gr.sample_and_hold_ff()
self.ffs_delay_input_for_correction = gr.delay(
gr.sizeof_gr_complex, dp.symbol_length
) # by delaying the input, we can use the ff offset estimation from the first symbol to correct the first symbol itself
self.ffs_nco = gr.frequency_modulator_fc(
1) # ffs_sample_and_hold directly outputs phase error per sample
self.ffs_mixer = gr.multiply_cc()
# calculate fine frequency error
self.connect(self.input, self.ffs_conj, self.ffs_mult)
self.connect(self.input, self.ffs_delay, (self.ffs_mult, 1))
self.connect(self.ffs_mult, self.ffs_moving_sum, self.ffs_angle)
# only use the value from the first half of the first symbol
self.connect(self.ffs_angle, self.ffs_angle_scale,
(self.ffs_sample_and_hold, 0))
self.connect(self.ns_detect, self.ffs_delay_sample_and_hold,
(self.ffs_sample_and_hold, 1))
# do the correction
self.connect(self.ffs_sample_and_hold, self.ffs_nco,
(self.ffs_mixer, 0))
self.connect(self.input, self.ffs_delay_input_for_correction,
(self.ffs_mixer, 1))
# output - corrected signal and start of DAB frames
self.connect(self.ffs_mixer, (self, 0))
self.connect(self.ffs_delay_sample_and_hold, (self, 1))
if debug:
self.connect(
self.ffs_angle,
gr.file_sink(gr.sizeof_float,
"debug/ofdm_sync_dab_ffs_angle.dat"))
self.connect(
self.ffs_sample_and_hold,
gr.multiply_const_ff(1. / (dp.T * 2 * pi)),
gr.file_sink(gr.sizeof_float,
"debug/ofdm_sync_dab_fine_freq_err_f.dat"))
self.connect(
self.ffs_mixer,
gr.file_sink(gr.sizeof_gr_complex,
"debug/ofdm_sync_dab_fine_freq_corrected_c.dat"))
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, mode, debug=False): """ OFDM time and coarse frequency synchronisation for DAB @param mode DAB mode (1-4) @param debug if True: write data streams out to files """ if mode<1 or mode>4: raise ValueError, "Invalid DAB mode: "+str(mode)+" (modes 1-4 exist)" # get the correct DAB parameters dp = parameters.dab_parameters(mode) rp = parameters.receiver_parameters(mode) gr.hier_block2.__init__(self,"ofdm_sync_dab", gr.io_signature(1, 1, gr.sizeof_gr_complex), # input signature gr.io_signature2(2, 2, gr.sizeof_gr_complex, 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) # # null-symbol detection # # (outsourced to detect_zero.py) self.ns_detect = detect_null.detect_null(dp.ns_length, debug) self.connect(self.input, self.ns_detect) # # fine frequency synchronisation # # the code for fine frequency synchronisation is adapted from # ofdm_sync_ml.py; it abuses the cyclic prefix to find the fine # frequency error, as suggested in "ML Estimation of Timing and # Frequency Offset in OFDM Systems", by Jan-Jaap van de Beek, # Magnus Sandell, Per Ola Börjesson, see # http://www.sm.luth.se/csee/sp/research/report/bsb96r.html self.ffs_delay = gr.delay(gr.sizeof_gr_complex, dp.fft_length) self.ffs_conj = gr.conjugate_cc() self.ffs_mult = gr.multiply_cc() # self.ffs_moving_sum = gr.fir_filter_ccf(1, [1]*dp.cp_length) self.ffs_moving_sum = dab_swig.moving_sum_cc(dp.cp_length) self.ffs_angle = gr.complex_to_arg() self.ffs_angle_scale = gr.multiply_const_ff(1./dp.fft_length) self.ffs_delay_sample_and_hold = gr.delay(gr.sizeof_char, dp.symbol_length) # sample the value at the end of the symbol .. self.ffs_sample_and_hold = gr.sample_and_hold_ff() self.ffs_delay_input_for_correction = gr.delay(gr.sizeof_gr_complex, dp.symbol_length) # by delaying the input, we can use the ff offset estimation from the first symbol to correct the first symbol itself self.ffs_nco = gr.frequency_modulator_fc(1) # ffs_sample_and_hold directly outputs phase error per sample self.ffs_mixer = gr.multiply_cc() # calculate fine frequency error self.connect(self.input, self.ffs_conj, self.ffs_mult) self.connect(self.input, self.ffs_delay, (self.ffs_mult, 1)) self.connect(self.ffs_mult, self.ffs_moving_sum, self.ffs_angle) # only use the value from the first half of the first symbol self.connect(self.ffs_angle, self.ffs_angle_scale, (self.ffs_sample_and_hold, 0)) self.connect(self.ns_detect, self.ffs_delay_sample_and_hold, (self.ffs_sample_and_hold, 1)) # do the correction self.connect(self.ffs_sample_and_hold, self.ffs_nco, (self.ffs_mixer, 0)) self.connect(self.input, self.ffs_delay_input_for_correction, (self.ffs_mixer, 1)) # output - corrected signal and start of DAB frames self.connect(self.ffs_mixer, (self, 0)) self.connect(self.ffs_delay_sample_and_hold, (self, 1)) if debug: self.connect(self.ffs_angle, gr.file_sink(gr.sizeof_float, "debug/ofdm_sync_dab_ffs_angle.dat")) self.connect(self.ffs_sample_and_hold, gr.multiply_const_ff(1./(dp.T*2*pi)), gr.file_sink(gr.sizeof_float, "debug/ofdm_sync_dab_fine_freq_err_f.dat")) self.connect(self.ffs_mixer, gr.file_sink(gr.sizeof_gr_complex, "debug/ofdm_sync_dab_fine_freq_corrected_c.dat"))
