[RX]
- write wavs - disabled DC offset correction. Adds noise to baseband signal - cleaned up git-svn-id: http://moon:8086/svn/matlab/trunk@73 801c6759-fa7c-4059-a304-17956f83a07c
This commit is contained in:
+131
-96
@@ -5,70 +5,18 @@ function ofdm_rx(filename, foff, flip_spec, SNR, show_H)
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% Example: ofdm_rx('xv.wav', 0, 0, 400, 1)
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% or ofdm_rx('yv.wav', 0, 0, 400, 1)
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% --------------------------------------------------------------
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close all;
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% --------------------------------------------------------------
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% fixed stuff
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% --------------------------------------------------------------
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MIN_ABS_H = 1e-10;
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drm_mode = 'B';
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drm_bw = '10k';
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[ofdm_drm_params, ofdm_spec_occ] = drm_params(drm_mode, drm_bw);
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[carrier_pilot, phi_pilot, mag_pilot] = getRefFreq(drm_mode);
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[carrier_time, phi_time, mag_time] = getRefTime(drm_mode);
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[W_syms, W_pilots] = calcWiener(drm_mode, drm_bw);
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filter_h = FIRCalcLowpass(0.25, 15);
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N = ofdm_drm_params.nu;
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Ng = ofdm_drm_params.ng;
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symbols_per_frame = ofdm_drm_params.nspf;
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symbols_to_delay = ofdm_drm_params.y;
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frames_per_window = 2*ofdm_drm_params.y;
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carriers = ofdm_spec_occ.kmin:ofdm_spec_occ.kmax;
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carrier_indexes = c2i(N, carriers);
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% Read wav file
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[fsize fs4] = wavread(filename, 'size');
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[xwav, fs4, nbits] = wavread(filename, 0);
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wav_numCh = fsize(2);
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wav_size = fsize(1);
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fs = fix(fs4/4);
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isModePassband = 0;
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if (wav_numCh == 1)
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fprintf('Mode: Passband\n');
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omega_xwav = (0.25-foff/fs4);
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isModePassband = 1;
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elseif (wav_numCh == 2)
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fprintf('Mode: Baseband\n');
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omega_xwav = (foff/fs4);
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else
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error('Cannot read file');
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end
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buf_recv = buffer();
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buf_Z = buffer();
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% Timing coarse stuff
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timingCoarse = struct('Z', 0, 'started', 0, 'sync_counter', 20, 'sync', 0, 'cp_off', 0, 'cp_off_', [], 'Nd', 0);
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% CFO coarse integer stuff
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cfoCoarseInteger = struct('Z', 0, 'started', 0, 'sync_counter', 20, 'sync', 0, 'f_err', 0);
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% CFO coarse fractional stuff
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cfoCoarseFractional = struct('Z', 0, 'started', 0, 'sync_counter', 20, 'sync', 0, 'f_err', 0, 'f_err_', [], 'df', 0, 'df_', []);
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% CFO Fine stuff
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cfoFine = struct('Z', 0, 'started', 0, 'sync_counter', 20, 'sync', 0, 'f_err', 0, 'f_err_', [], 'df', 0, 'df_', [], 'Xlast', [], 'phi', 0, 'bin_track', 1);
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% Frame timing stuff
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frameTiming = struct('Z', 0, 'started', 0, 'sync_counter', 20, 'sync', 0, 'kc_max', -1000, 'n', 0, 'n_max', 0);
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% Equalization stuff
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equalizer = struct('Z', 0, 'started', 0, 'sync_counter', 20, 'sync', 0, 'sync_frame_num', 0, 'f_err', 1000, 'f_err_', [], 's', 0, 'm', 0, 'kk', 1, 'eps_abs_h', MIN_ABS_H);
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% Mode 'B'
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fac_cell_list = ...
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{
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[],
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@@ -88,44 +36,116 @@ fac_cell_list = ...
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[]
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};
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filter_z = [];
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fileChunkSize = N;
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% --------------------------------------------------------------
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% Precalculation
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% --------------------------------------------------------------
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[ofdm_drm_params, ofdm_spec_occ] = drm_params(drm_mode, drm_bw);
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[carrier_pilot, phi_pilot, mag_pilot] = getRefFreq(drm_mode);
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[carrier_time, phi_time, mag_time] = getRefTime(drm_mode);
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[W_syms, W_pilots] = calcWiener(drm_mode, drm_bw);
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filter_h = FIRCalcLowpass(0.25, 15);
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N = ofdm_drm_params.nu;
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Ng = ofdm_drm_params.ng;
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symbols_per_frame = ofdm_drm_params.nspf;
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symbols_to_delay = ofdm_drm_params.y;
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frames_per_window = 2*ofdm_drm_params.y;
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carriers = ofdm_spec_occ.kmin:ofdm_spec_occ.kmax;
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carrier_indexes = c2i(N, carriers);
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% Read wav file
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[wav_size wav_fs] = wavread(filename, 'size');
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[wav_x, wav_fs, nbits] = wavread(filename, 0);
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wav_numCh = wav_size(2);
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wav_size = wav_size(1);
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% --------------------------------------------------------------
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% Determine data mode
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% --------------------------------------------------------------
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isModePassband = 0;
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if (wav_numCh == 1)
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fprintf('Mode: Passband\n');
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isModePassband = 1;
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fs = fix(wav_fs/4);
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fileChunkSize = N; % Fix: don't leave loop, if file has been consumed. There may be samples left in buf_recv to process
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elseif (wav_numCh == 2)
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fprintf('Mode: Baseband\n');
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fs = wav_fs;
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fileChunkSize = N/4; % Fix: don't leave loop, if file has been consumed. There may be samples left in buf_recv to process
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else
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error('Cannot read file');
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end
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% --------------------------------------------------------------
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% Timing coarse stuff
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timingCoarse = struct('Z', 0, 'started', 0, 'sync_counter', 20, 'sync', 0, 'cp_off', 0, 'cp_off_', [], 'Nd', 0);
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% CFO coarse integer stuff
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cfoCoarseInteger = struct('Z', 0, 'started', 0, 'sync_counter', 20, 'sync', 0, 'f_err', 0);
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% CFO coarse fractional stuff
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cfoCoarseFractional = struct('Z', 0, 'started', 0, 'sync_counter', 20, 'sync', 0, 'f_err', 0, 'f_err_', [], 'df', 0, 'df_', []);
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% CFO Fine stuff
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cfoFine = struct('Z', 0, 'started', 0, 'sync_counter', 20, 'sync', 0, 'f_err', 0, 'f_err_', [], 'df', 0, 'df_', [], 'Xlast', [], 'phi', 0, 'bin_track', 1);
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% Frame timing stuff
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frameTiming = struct('Z', 0, 'started', 0, 'sync_counter', 20, 'sync', 0, 'kc_max', -1000, 'n', 0, 'n_max', 0);
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% Equalization stuff
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equalizer = struct('Z', 0, 'started', 0, 'sync_counter', 20, 'sync', 0, 'sync_frame_num', 0, 'f_err', 1000, 'f_err_', [], 's', 0, 'm', 0, 'kk', 1, 'eps_abs_h', MIN_ABS_H);
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fileCunkCounter = 0;
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phi_xwav = 0;
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phi_mix = 0;
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phi_foff = 0;
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df_track = 0;
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df_track_ = [];
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filter_z = [];
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max_H_plot = 0;
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symbol_count = -1;
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fileRemain = wav_size;
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while(fileRemain > fileChunkSize)
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buf_recv = buffer();
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buf_Z = buffer();
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% --------------------------------------------------------------
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% Main loop
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% --------------------------------------------------------------
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while(fileRemain > fileChunkSize) % ToDo: don't leave loop, if file has been consumed. There may be samples left in buf_recv to process
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n0 = fileCunkCounter*fileChunkSize+1;
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n1 = (fileCunkCounter+1)*fileChunkSize;
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[xwav] = wavread(filename, [n0 n1]);
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[wav_x] = wavread(filename, [n0 n1]);
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if (~isModePassband)
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xwav = xwav(:, 1) + j*xwav(:, 2);
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wav_x = wav_x(:, 1) + j*wav_x(:, 2);
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end
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xwav = xwav - mean(xwav);
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x = xwav.*exp(-j*(2*pi*omega_xwav*(0:fileChunkSize-1)' + phi_xwav));
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phi_xwav = mod(phi_xwav + 2*pi*omega_xwav*fileChunkSize, 2*pi);
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% ToDo: Remove DC
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x = wav_x;
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if (isModePassband)
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x = x.*exp(-j*(2*pi*0.25*(0:length(x)-1)' + phi_mix));
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phi_mix = mod(phi_mix + 2*pi*0.25*length(x), 2*pi);
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[x, filter_z] = filter(filter_h, 1, x, filter_z);
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x = x(1:4:length(x));
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end
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x = x.*exp(-j*(2*pi*(foff/fs)*(0:length(x)-1)' + phi_foff));
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phi_foff = mod(phi_foff + 2*pi*(foff/fs)*length(x), 2*pi);
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if flip_spec
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x = conj(x);
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end
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% add noise
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x = awgn(x, SNR);
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if (isModePassband)
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[x, filter_z] = filter(filter_h, 1, x, filter_z);
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buf_recv.write(x(1:4:length(x)));
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else
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buf_recv.write(x);
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end
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% Write to buffer
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buf_recv.write(x);
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% --------------------------------------------------------------
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% Timing coarse
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@@ -136,22 +156,24 @@ while(fileRemain > fileChunkSize)
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end
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x = buf_recv.read(N+Ng);
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[timingCoarse.cp_off, timingCoarse.Nd, valid, timingCoarse.Z] = timing_coarse(x, N, Ng, Ng, timingCoarse.Z);
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if (valid)
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timingCoarse.cp_off_ = [timingCoarse.cp_off_ timingCoarse.cp_off];
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if (timingCoarse.sync_counter > 0)
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timingCoarse.sync_counter = timingCoarse.sync_counter - 1;
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else
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timingCoarse.sync = 1;
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if ~isempty(x)
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[timingCoarse.cp_off, timingCoarse.Nd, valid, timingCoarse.Z] = timing_coarse(x, N, Ng, Ng, timingCoarse.Z);
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if (valid)
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timingCoarse.cp_off_ = [timingCoarse.cp_off_ timingCoarse.cp_off];
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if (timingCoarse.sync_counter > 0)
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timingCoarse.sync_counter = timingCoarse.sync_counter - 1;
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else
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timingCoarse.sync = 1;
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end
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end;
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if (timingCoarse.sync)
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timingCoarse.cp_off = round(median(timingCoarse.cp_off_));
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% Reset buffer to Cp offset
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buf_recv.setReadIndex(timingCoarse.cp_off);
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fprintf(' (cp_off=%d, Nd=%d)\n', timingCoarse.cp_off, timingCoarse.Nd);
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end
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end;
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if (timingCoarse.sync)
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timingCoarse.cp_off = round(median(timingCoarse.cp_off_));
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% Reset buffer to Cp offset
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buf_recv.setReadIndex(timingCoarse.cp_off);
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fprintf(' (cp_off=%d, Nd=%d)\n', timingCoarse.cp_off, timingCoarse.Nd);
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end
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end
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@@ -285,8 +307,6 @@ while(fileRemain > fileChunkSize)
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H_raw = zeros(length(carriers),1);
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fprintf('Channel estimation and symbol reception\n');
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figure(100);
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end
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Z = transpose(buf_Z.read(N));
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@@ -313,6 +333,7 @@ while(fileRemain > fileChunkSize)
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% Get the correctly delayed symbols
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Z = buf_Z.readAt(N, -N*(symbols_to_delay+1));
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sym = Z(carrier_indexes).';
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% Get the correctly delayed raw channel estimate
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@@ -368,7 +389,7 @@ while(fileRemain > fileChunkSize)
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hold off;
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pause(0.01);
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else
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elseif (equalizer.sync)
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fac_c = fac_cell_list{mod(equalizer.s-symbols_to_delay, symbols_per_frame)+1};
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if (~isempty(fac_c))
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fac_i = fac_c - ofdm_spec_occ.kmin + 1;
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@@ -387,11 +408,13 @@ while(fileRemain > fileChunkSize)
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end
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end
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end
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% --------------------------------------------------------------
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fileRemain = fileRemain - fileChunkSize;
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fileCunkCounter = fileCunkCounter + 1;
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end
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% --------------------------------------------------------------
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% Output
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% --------------------------------------------------------------
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figure;
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plot(0:length(timingCoarse.cp_off_)-1, timingCoarse.cp_off_, 0:length(timingCoarse.cp_off_)-1, timingCoarse.cp_off*ones(size(timingCoarse.cp_off_)), 'r-'); grid; title('cp_{off}')
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@@ -420,20 +443,32 @@ y = [a(3) a(4)];
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plot(x-1,y, 'r-');
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hold off;
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if 0
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% --------------------------------------------------------------
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% Write wave files
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% --------------------------------------------------------------
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fprintf('Writing wav files ');
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buf_recv.setReadIndex(0);
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x = buf_recv.read(buf_recv.len());
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fprintf('.');
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xout = [real(x) imag(x)];
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wavwrite(xout,fs,nbits,'rx_x.wav');
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% Modulate on carrier
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fprintf('.');
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xup = upsample(x, 4);
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hlp = FIRCalcLowpass(0.25, 129);
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fprintf('.');
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xup = filter(hlp, 1, xup);
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y = exp(j*2*pi.*(0:length(xup)-1)'*0.25) .* xup;
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wavwrite(y,fs4,nbits,'rx_y.wav');
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end
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fprintf('.');
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wavwrite(y,4*fs,nbits,'rx_y.wav');
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fprintf(' done\n');
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% --------------------------------------------------------------
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function Y = spec_order(N, X)
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Y = [X(N/2+1:N)' X(1:N/2)']';
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