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https://github.com/zjs81/meshcore-open.git
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updated ui added new features
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zach
+365
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% fdmdv_demod.m
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%
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% Demodulator function for FDMDV modem (Octave version). Requires
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% 8kHz sample rate raw files as input
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%
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% Copyright David Rowe 2012
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% This program is distributed under the terms of the GNU General Public License
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% Version 2
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%
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function fdmdv_demod(rawfilename, nbits, NumCarriers=14, errorpatternfilename, symbolfilename)
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pkg load signal;
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fdmdv; % include modem code
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f = fdmdv_init(NumCarriers);
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Nc = f.Nc; Nb = f.Nb; Rs = f.Rs; M = f.M; Fs = f.Fs; Nsync_mem = f.Nsync_mem;
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test_bits = f.test_bits; Q = f.Q; P = f.P;
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modulation = 'dqpsk';
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fin = fopen(rawfilename, "rb");
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gain = 1000;
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frames = nbits/(Nc*Nb);
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prev_rx_symbols = ones(Nc+1,1);
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foff_phase_rect = 1;
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% BER stats
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total_bit_errors = 0;
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total_bits = 0;
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bit_errors_log = [];
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sync_log = [];
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test_frame_sync_log = [];
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test_frame_sync_state = 0;
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error_pattern_log = [];
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% SNR states
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sig_est = zeros(Nc+1,1);
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noise_est = zeros(Nc+1,1);
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% logs of various states for plotting
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rx_symbols_log = [];
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rx_timing_log = [];
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foff_coarse_log = [];
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foff_log = [];
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rx_fdm_log = [];
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snr_est_log = [];
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% misc states
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nin = M; % timing correction for sample rate differences
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foff = 0;
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fest_state = 0;
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fest_timer = 0;
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sync_mem = zeros(1,Nsync_mem);
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sync = 0;
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sync_log = [];
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% spectrum states
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Nspec=1024;
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spec_mem=zeros(1,Nspec);
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SdB = zeros(1,Nspec);
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% optionally save output symbols
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if nargin == 5
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fm = fopen(symbolfilename,"wb");
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dual_rx_symbols = zeros(1, 2*Nc);
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dual_rx_bits = zeros(1,2*Nc*Nb);
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end
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atimer = 0;
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% Main loop ----------------------------------------------------
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for fr=1:frames
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% obtain nin samples of the test input signal
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for i=1:nin
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rx_fdm(i) = fread(fin, 1, "short")/gain;
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end
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rx_fdm_log = [rx_fdm_log rx_fdm(1:nin)];
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% update spectrum
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l=length(rx_fdm);
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spec_mem(1:Nspec-l) = spec_mem(l+1:Nspec);
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spec_mem(Nspec-l+1:Nspec) = rx_fdm;
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S=fft(spec_mem.*hanning(Nspec)',Nspec);
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SdB = 0.9*SdB + 0.1*20*log10(abs(S));
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% shift down to complex baseband
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for i=1:nin
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f.fbb_phase_rx = f.fbb_phase_rx*f.fbb_rect';
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rx_fdm(i) = rx_fdm(i)*f.fbb_phase_rx;
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end
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mag = abs(f.fbb_phase_rx);
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f.fbb_phase_rx /= mag;
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% frequency offset estimation and correction
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[pilot prev_pilot f.pilot_lut_index f.prev_pilot_lut_index] = get_pilot(f, f.pilot_lut_index, f.prev_pilot_lut_index, nin);
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[foff_coarse S1 S2 f] = rx_est_freq_offset(f, rx_fdm, pilot, prev_pilot, nin, !sync );
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if sync == 0
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foff = foff_coarse;
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end
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foff_coarse_log = [foff_coarse_log foff_coarse];
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foff_rect = exp(j*2*pi*foff/Fs);
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for i=1:nin
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foff_phase_rect *= foff_rect';
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rx_fdm_fcorr(i) = rx_fdm(i)*foff_phase_rect;
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end
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% baseband processing
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if 0
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% easier to understand, but more memory and CPU hungry filtering and down conversion
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[rx_baseband f] = fdm_downconvert(f, rx_fdm_fcorr, nin);
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[rx_filt f] = rx_filter(f, rx_baseband, nin);
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else
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% more efficient filtering and down conversion
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[rx_fdm_filter f] = rxdec_filter(f, rx_fdm_fcorr, nin);
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[rx_filt f] = down_convert_and_rx_filter(f, rx_fdm_filter, nin, M/Q);
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end
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[rx_symbols rx_timing env f] = rx_est_timing(f, rx_filt, nin);
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rx_timing_log = [rx_timing_log rx_timing];
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nin = M;
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if rx_timing > M/P
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nin += M/P;
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end
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if rx_timing < -M/P;
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nin -= M/P;
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end
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%printf("fr: %d rx_timing: %d nin = %d\n", fr, rx_timing, nin);
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rx_symbols_log = [rx_symbols_log rx_symbols.*conj(prev_rx_symbols./abs(prev_rx_symbols))*exp(j*pi/4)];
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[rx_bits sync_bit f_err pd] = psk_to_bits(f, prev_rx_symbols, rx_symbols, modulation);
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% optionally save output symbols
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if (nargin == 5)
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% this free runs, and is reset by an "entered sync" state
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if (sync_track == 0)
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sync_track = 1;
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else
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sync_track = 0;
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end
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if (track == 1) && (sync_track == 1)
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dual_rx_symbols(Nc+1:2*Nc) = rx_symbols(1:Nc).*conj(prev_rx_symbols(1:Nc)./abs(prev_rx_symbols(1:Nc)));
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dual_rx_symbols_float32 = []; k = 1;
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for i=1:2*Nc
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dual_rx_symbols_float32(k++) = real(dual_rx_symbols(i));
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dual_rx_symbols_float32(k++) = imag(dual_rx_symbols(i));
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end
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fwrite(fm, dual_rx_symbols_float32, "float32");
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dual_rx_bits(Nc*Nb+1:2*Nc*Nb) = rx_bits;
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%dump_bits(dual_rx_bits);
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else
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dual_rx_symbols(1:Nc) = rx_symbols(1:Nc).*conj(prev_rx_symbols(1:Nc)./abs(prev_rx_symbols(1:Nc)));
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dual_rx_bits(1:Nc*Nb) = rx_bits;
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end
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end
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% update some states
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prev_rx_symbols = rx_symbols;
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[sig_est noise_est] = snr_update(f, sig_est, noise_est, pd);
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snr_est = calc_snr(f, sig_est, noise_est);
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snr_est_log = [snr_est_log snr_est];
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foff -= 0.5*f_err;
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foff_log = [foff_log foff];
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% freq est state machine
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[sync reliable_sync_bit fest_state fest_timer sync_mem] = freq_state(f, sync_bit, fest_state, fest_timer, sync_mem);
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sync_log = [sync_log sync];
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% count bit errors if we find a test frame
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[test_frame_sync bit_errors error_pattern f] = put_test_bits(f, rx_bits);
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if (test_frame_sync == 1)
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if (bit_errors)
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printf("fr: %d bit_errors: %d\n", fr, bit_errors);
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end
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total_bit_errors = total_bit_errors + bit_errors;
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total_bits = total_bits + f.Ntest_bits;
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bit_errors_log = [bit_errors_log bit_errors/f.Ntest_bits];
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else
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bit_errors_log = [bit_errors_log 0];
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end
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% test frame sync state machine, just for more informative plots
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next_test_frame_sync_state = test_frame_sync_state;
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if (test_frame_sync_state == 0)
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if (test_frame_sync == 1)
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next_test_frame_sync_state = 1;
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test_frame_count = 0;
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end
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end
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if (test_frame_sync_state == 1)
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% we only expect another test_frame_sync pulse every 4 symbols
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test_frame_count++;
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if (test_frame_count == 4)
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test_frame_count = 0;
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if ((test_frame_sync == 0))
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next_test_frame_sync_state = 0;
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else
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error_pattern_log = [error_pattern_log error_pattern];
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end
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end
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end
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test_frame_sync_state = next_test_frame_sync_state;
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test_frame_sync_log = [test_frame_sync_log test_frame_sync_state];
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end
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if nargin == 5
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fclose(fm);
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etfilename = strcat(strtok(symbolfilename,"."),"_et.bin");
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fet = fopen(etfilename, "wb");
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fwrite(fet, entered_track_log, "short");
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fclose(fet);
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end
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% ---------------------------------------------------------------------
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% Print Stats
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% ---------------------------------------------------------------------
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% Peak to Average Power Ratio calcs from http://www.dsplog.com
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papr = max(rx_fdm_log.*conj(rx_fdm_log)) / mean(rx_fdm_log.*conj(rx_fdm_log));
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papr_dB = 10*log10(papr);
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ber = total_bit_errors / total_bits;
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printf("%d bits %d errors BER: %1.4f PAPR(rx): %1.2f dB\n",total_bits, total_bit_errors, ber, papr_dB);
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% ---------------------------------------------------------------------
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% Plots
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% ---------------------------------------------------------------------
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xt = (1:frames)/Rs;
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secs = frames/Rs;
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figure(1); clf;
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[n m] = size(rx_symbols_log);
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plot(real(rx_symbols_log(1:Nc+1,15:m)),imag(rx_symbols_log(1:Nc+1,15:m)),'+')
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axis([-2 2 -2 2]);
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title('Scatter Diagram');
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figure(2); clf;
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plot(xt, rx_timing_log)
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title('timing offset (samples)');
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figure(3);
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plot(xt, foff_log, '-;freq offset;')
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%hold on;
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%plot(xt, sync_log*75, 'r;course-fine;');
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%hold off;
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title('Freq offset (Hz)');
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grid;
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figure(4); clf;
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plot_specgram(rx_fdm_log, Fs);
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figure(5); clf;
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subplot(311)
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stem(xt, sync_log)
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axis([0 secs 0 1.5]);
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title('BPSK Sync')
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subplot(312)
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stem(xt, bit_errors_log);
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title('Bit Errors for test frames')
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subplot(313)
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plot(xt, test_frame_sync_log);
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axis([0 secs 0 1.5]);
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title('Test Frame Sync')
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figure(6); clf;
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subplot(211);
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plot(xt, snr_est_log);
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title('SNR Estimates')
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subplot(212)
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snrdB_pc = 20*log10(sig_est(1:Nc+1)) - 20*log10(noise_est(1:Nc+1));
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bar(snrdB_pc(1:Nc) - mean(snrdB_pc(1:Nc)))
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axis([0 Nc+1 -3 3]);
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figure(7); clf;
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hold on;
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lep = length(error_pattern_log);
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if lep != 0
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for p=1:Nc
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plot(p + 0.25*error_pattern_log((p-1)*2+1:Nc*Nb:lep));
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plot(0.30 + p + 0.25*error_pattern_log(p*2:Nc*Nb:lep),'r')
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end
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hold off;
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axis([1 lep/(Nc*Nb) 0 Nc])
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end
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figure(8); clf;
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subplot(211)
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[a b] = size(rx_fdm_log);
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xt1 = (1:b)/Fs;
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plot(xt1, rx_fdm_log);
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title('Rx FDM Signal');
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subplot(212)
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plot((0:Nspec/2-1)*Fs/Nspec, SdB(1:Nspec/2) - 20*log10(Nspec/2))
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axis([0 Fs/2 -40 0])
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grid
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title('FDM Rx Spectrum');
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if 0
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% interleaving tests
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load ../unittest/inter560.txt
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lep = length(error_pattern_log);
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lep = floor(lep/560)*560;
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error_pattern_log_inter = zeros(1,lep);
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for i=1:560:lep
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for j=1:560
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%printf("i: %4d j: %4d inter560(j): %4d\n", i,j,inter560(j));
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index = inter560(j);
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error_pattern_log_inter(i-1+index+1) = error_pattern_log(i-1+j);
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end
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end
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figure(8)
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clf;
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hold on;
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for p=1:Nc
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plot(p + 0.25*error_pattern_log_inter((p-1)*2+1:Nc*Nb:lep));
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plot(0.30 + p + 0.25*error_pattern_log_inter(p*2:Nc*Nb:lep),'r')
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end
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hold off;
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axis([1 lep/(Nc*Nb) 0 Nc])
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end
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% optionally save error pattern file
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if nargin == 4
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fout = fopen(errorpatternfilename, "wb");
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fwrite(fout, error_pattern_log, "short");
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fclose(fout);
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end
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endfunction
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