diff options
Diffstat (limited to 'gnuradio-examples/python/ofdm/ofdm_receiver.py')
| -rw-r--r-- | gnuradio-examples/python/ofdm/ofdm_receiver.py | 147 |
1 files changed, 147 insertions, 0 deletions
diff --git a/gnuradio-examples/python/ofdm/ofdm_receiver.py b/gnuradio-examples/python/ofdm/ofdm_receiver.py new file mode 100644 index 0000000000..467e3af05e --- /dev/null +++ b/gnuradio-examples/python/ofdm/ofdm_receiver.py @@ -0,0 +1,147 @@ +#!/usr/bin/env python +# +# Copyright 2004,2005,2006 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 2, 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. +# + +import math +from gnuradio import gr +from gnuradio import audio +from gnuradio.eng_option import eng_option +from optparse import OptionParser + +class ofdm_receiver(gr.hier_block): + def __init__(self, fg, fft_length, symbol_length, snr): + self.input = gr.add_const_cc(0) # Kluge that goes away with hier_block2 + + self.fg = fg + + cpsize = symbol_length - fft_length; + + SNR = 10.0**(snr/10.0) + rho = SNR / (SNR + 1.0) + + # ML Sync + + # Energy Detection from ML Sync + + # Create a delay line + delayline = [0.0 for i in range(fft_length+1)] + delayline[fft_length] = 1.0 + self.delay = gr.fir_filter_ccf(1,delayline) + self.fg.connect(self.input, self.delay) + + # magnitude squared blocks + self.magsqrd1 = gr.complex_to_mag_squared() + self.magsqrd2 = gr.complex_to_mag_squared() + self.adder = gr.add_ff() + + moving_sum_taps = [rho/2 for i in range(cpsize)] + self.moving_sum_filter = gr.fir_filter_fff(1,moving_sum_taps) + + self.fg.connect(self.input,self.magsqrd1) + self.fg.connect(self.delay,self.magsqrd2) + self.fg.connect(self.magsqrd1,(self.adder,0)) + self.fg.connect(self.magsqrd2,(self.adder,1)) + self.fg.connect(self.adder,self.moving_sum_filter) + + + # Correlation from ML Sync + self.conjg = gr.conjugate_cc(); + self.mixer = gr.multiply_cc(); + + movingsum2_taps = [1.0 for i in range(cpsize)] + self.movingsum2 = gr.fir_filter_ccf(1,movingsum2_taps) + + + # Correlator data handler + self.c2mag = gr.complex_to_mag() + self.angle = gr.complex_to_arg() + self.fg.connect(self.input,(self.mixer,1)) + self.fg.connect(self.delay,self.conjg,(self.mixer,0)) + self.fg.connect(self.mixer,self.movingsum2,self.c2mag) + self.fg.connect(self.movingsum2,self.angle) + + # ML Sync output arg, need to find maximum point of this + self.diff = gr.sub_ff() + self.fg.connect(self.c2mag,(self.diff,0)) + self.fg.connect(self.moving_sum_filter,(self.diff,1)) + + #ML measurements input to sampler block and detect + nco_sensitivity = 1.0/fft_length + self.f2c = gr.float_to_complex() + self.sampler = gr.ofdm_sampler(fft_length,symbol_length) + self.pkt_detect = gr.peak_detector_ff(0.2, 0.25, 30, 0.0001) + self.dpll = gr.dpll_ff(float(symbol_length),0.01) + self.sample_and_hold = gr.sample_and_hold_ff() + self.nco = gr.frequency_modulator_fc(nco_sensitivity) + self.inv = gr.multiply_const_ff(-1) + self.sigmix = gr.multiply_cc() + + # Mix the signal with an NCO controlled by the sync loop + self.fg.connect(self.input, (self.sigmix,0)) + self.fg.connect(self.nco, (self.sigmix,1)) + self.fg.connect(self.sigmix, (self.sampler,0)) + + sample_trigger = 0 + if sample_trigger: + # for testing + peak_null = gr.null_sink(gr.sizeof_float) + data = 640*[0,] + data[639] = 1 + peak_trigger = gr.vector_source_f(data, True) + + self.fg.connect(self.pkt_detect, peak_null) + self.fg.connect(peak_trigger, self.f2c, (self.sampler,1)) + self.fg.connect(peak_trigger, (self.sample_and_hold,1)) + + # use the sync loop values to set the sampler and the NCO + # self.diff = theta + # self.angle = epsilon + + self.fg.connect(self.diff, self.pkt_detect) + use_dpll = 1 + if not sample_trigger: + if use_dpll: + self.fg.connect(self.pkt_detect, self.dpll,self.f2c, (self.sampler,1)) + self.fg.connect(self.dpll, (self.sample_and_hold,1)) + if not use_dpll: + self.fg.connect(self.pkt_detect, self.f2c, (self.sampler,1)) + self.fg.connect(self.pkt_detect, (self.sample_and_hold,1)) + + self.fg.connect(self.angle, (self.sample_and_hold,0)) + self.fg.connect(self.sample_and_hold, self.inv, self.nco) + + + if 0: + self.fg.connect(self.diff, gr.file_sink(gr.sizeof_float, "theta_f.dat")) + self.fg.connect(self.angle, gr.file_sink(gr.sizeof_float, "epsilon_f.dat")) + if use_dpll: + self.fg.connect(self.dpll, gr.file_sink(gr.sizeof_float, "dpll_pulses.dat")) + if sample_trigger: + self.fg.connect(peak_trigger, gr.file_sink(gr.sizeof_float, "peaks_f.dat")) + else: + self.fg.connect(self.pkt_detect, gr.file_sink(gr.sizeof_float, "peaks_f.dat")) + + self.fg.connect(self.sample_and_hold, gr.file_sink(gr.sizeof_float, "sample_and_hold_f.dat")) + self.fg.connect(self.nco, gr.file_sink(gr.sizeof_gr_complex, "nco_c.dat")) + self.fg.connect(self.input, gr.file_sink(gr.sizeof_gr_complex, "input_c.dat")) + self.fg.connect(self.sigmix, gr.file_sink(gr.sizeof_gr_complex, "output_c.dat")) + + gr.hier_block.__init__(self, fg, self.input, self.sampler) |