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- 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:
jens
2015-05-03 16:51:25 +00:00
parent 982bf2c32f
commit 7c1bd55a5e
1 changed files with 131 additions and 96 deletions
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ofdm/ofdm_rx.m
+130 -95
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@@ -5,70 +5,18 @@ function ofdm_rx(filename, foff, flip_spec, SNR, show_H)
% Example: ofdm_rx('xv.wav', 0, 0, 400, 1) % Example: ofdm_rx('xv.wav', 0, 0, 400, 1)
% or ofdm_rx('yv.wav', 0, 0, 400, 1) % or ofdm_rx('yv.wav', 0, 0, 400, 1)
% --------------------------------------------------------------
close all; close all;
% --------------------------------------------------------------
% fixed stuff
% --------------------------------------------------------------
MIN_ABS_H = 1e-10; MIN_ABS_H = 1e-10;
drm_mode = 'B'; drm_mode = 'B';
drm_bw = '10k'; drm_bw = '10k';
[ofdm_drm_params, ofdm_spec_occ] = drm_params(drm_mode, drm_bw); % Mode 'B'
[carrier_pilot, phi_pilot, mag_pilot] = getRefFreq(drm_mode);
[carrier_time, phi_time, mag_time] = getRefTime(drm_mode);
[W_syms, W_pilots] = calcWiener(drm_mode, drm_bw);
filter_h = FIRCalcLowpass(0.25, 15);
N = ofdm_drm_params.nu;
Ng = ofdm_drm_params.ng;
symbols_per_frame = ofdm_drm_params.nspf;
symbols_to_delay = ofdm_drm_params.y;
frames_per_window = 2*ofdm_drm_params.y;
carriers = ofdm_spec_occ.kmin:ofdm_spec_occ.kmax;
carrier_indexes = c2i(N, carriers);
% Read wav file
[fsize fs4] = wavread(filename, 'size');
[xwav, fs4, nbits] = wavread(filename, 0);
wav_numCh = fsize(2);
wav_size = fsize(1);
fs = fix(fs4/4);
isModePassband = 0;
if (wav_numCh == 1)
fprintf('Mode: Passband\n');
omega_xwav = (0.25-foff/fs4);
isModePassband = 1;
elseif (wav_numCh == 2)
fprintf('Mode: Baseband\n');
omega_xwav = (foff/fs4);
else
error('Cannot read file');
end
buf_recv = buffer();
buf_Z = buffer();
% Timing coarse stuff
timingCoarse = struct('Z', 0, 'started', 0, 'sync_counter', 20, 'sync', 0, 'cp_off', 0, 'cp_off_', [], 'Nd', 0);
% CFO coarse integer stuff
cfoCoarseInteger = struct('Z', 0, 'started', 0, 'sync_counter', 20, 'sync', 0, 'f_err', 0);
% CFO coarse fractional stuff
cfoCoarseFractional = struct('Z', 0, 'started', 0, 'sync_counter', 20, 'sync', 0, 'f_err', 0, 'f_err_', [], 'df', 0, 'df_', []);
% CFO Fine stuff
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);
% Frame timing stuff
frameTiming = struct('Z', 0, 'started', 0, 'sync_counter', 20, 'sync', 0, 'kc_max', -1000, 'n', 0, 'n_max', 0);
% Equalization stuff
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);
fac_cell_list = ... fac_cell_list = ...
{ {
[], [],
@@ -88,30 +36,106 @@ fac_cell_list = ...
[] []
}; };
filter_z = []; % --------------------------------------------------------------
fileChunkSize = N; % Precalculation
% --------------------------------------------------------------
[ofdm_drm_params, ofdm_spec_occ] = drm_params(drm_mode, drm_bw);
[carrier_pilot, phi_pilot, mag_pilot] = getRefFreq(drm_mode);
[carrier_time, phi_time, mag_time] = getRefTime(drm_mode);
[W_syms, W_pilots] = calcWiener(drm_mode, drm_bw);
filter_h = FIRCalcLowpass(0.25, 15);
N = ofdm_drm_params.nu;
Ng = ofdm_drm_params.ng;
symbols_per_frame = ofdm_drm_params.nspf;
symbols_to_delay = ofdm_drm_params.y;
frames_per_window = 2*ofdm_drm_params.y;
carriers = ofdm_spec_occ.kmin:ofdm_spec_occ.kmax;
carrier_indexes = c2i(N, carriers);
% Read wav file
[wav_size wav_fs] = wavread(filename, 'size');
[wav_x, wav_fs, nbits] = wavread(filename, 0);
wav_numCh = wav_size(2);
wav_size = wav_size(1);
% --------------------------------------------------------------
% Determine data mode
% --------------------------------------------------------------
isModePassband = 0;
if (wav_numCh == 1)
fprintf('Mode: Passband\n');
isModePassband = 1;
fs = fix(wav_fs/4);
fileChunkSize = N; % Fix: don't leave loop, if file has been consumed. There may be samples left in buf_recv to process
elseif (wav_numCh == 2)
fprintf('Mode: Baseband\n');
fs = wav_fs;
fileChunkSize = N/4; % Fix: don't leave loop, if file has been consumed. There may be samples left in buf_recv to process
else
error('Cannot read file');
end
% --------------------------------------------------------------
% Timing coarse stuff
timingCoarse = struct('Z', 0, 'started', 0, 'sync_counter', 20, 'sync', 0, 'cp_off', 0, 'cp_off_', [], 'Nd', 0);
% CFO coarse integer stuff
cfoCoarseInteger = struct('Z', 0, 'started', 0, 'sync_counter', 20, 'sync', 0, 'f_err', 0);
% CFO coarse fractional stuff
cfoCoarseFractional = struct('Z', 0, 'started', 0, 'sync_counter', 20, 'sync', 0, 'f_err', 0, 'f_err_', [], 'df', 0, 'df_', []);
% CFO Fine stuff
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);
% Frame timing stuff
frameTiming = struct('Z', 0, 'started', 0, 'sync_counter', 20, 'sync', 0, 'kc_max', -1000, 'n', 0, 'n_max', 0);
% Equalization stuff
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);
fileCunkCounter = 0; fileCunkCounter = 0;
phi_xwav = 0; phi_mix = 0;
phi_foff = 0;
df_track = 0; df_track = 0;
df_track_ = []; df_track_ = [];
filter_z = [];
max_H_plot = 0; max_H_plot = 0;
symbol_count = -1; symbol_count = -1;
fileRemain = wav_size; fileRemain = wav_size;
while(fileRemain > fileChunkSize) buf_recv = buffer();
buf_Z = buffer();
% --------------------------------------------------------------
% Main loop
% --------------------------------------------------------------
while(fileRemain > fileChunkSize) % ToDo: don't leave loop, if file has been consumed. There may be samples left in buf_recv to process
n0 = fileCunkCounter*fileChunkSize+1; n0 = fileCunkCounter*fileChunkSize+1;
n1 = (fileCunkCounter+1)*fileChunkSize; n1 = (fileCunkCounter+1)*fileChunkSize;
[xwav] = wavread(filename, [n0 n1]); [wav_x] = wavread(filename, [n0 n1]);
if (~isModePassband) if (~isModePassband)
xwav = xwav(:, 1) + j*xwav(:, 2); wav_x = wav_x(:, 1) + j*wav_x(:, 2);
end end
xwav = xwav - mean(xwav);
x = xwav.*exp(-j*(2*pi*omega_xwav*(0:fileChunkSize-1)' + phi_xwav)); % ToDo: Remove DC
phi_xwav = mod(phi_xwav + 2*pi*omega_xwav*fileChunkSize, 2*pi); x = wav_x;
if (isModePassband)
x = x.*exp(-j*(2*pi*0.25*(0:length(x)-1)' + phi_mix));
phi_mix = mod(phi_mix + 2*pi*0.25*length(x), 2*pi);
[x, filter_z] = filter(filter_h, 1, x, filter_z);
x = x(1:4:length(x));
end
x = x.*exp(-j*(2*pi*(foff/fs)*(0:length(x)-1)' + phi_foff));
phi_foff = mod(phi_foff + 2*pi*(foff/fs)*length(x), 2*pi);
if flip_spec if flip_spec
x = conj(x); x = conj(x);
@@ -120,12 +144,8 @@ while(fileRemain > fileChunkSize)
% add noise % add noise
x = awgn(x, SNR); x = awgn(x, SNR);
if (isModePassband) % Write to buffer
[x, filter_z] = filter(filter_h, 1, x, filter_z); buf_recv.write(x);
buf_recv.write(x(1:4:length(x)));
else
buf_recv.write(x);
end
% -------------------------------------------------------------- % --------------------------------------------------------------
% Timing coarse % Timing coarse
@@ -136,22 +156,24 @@ while(fileRemain > fileChunkSize)
end end
x = buf_recv.read(N+Ng); x = buf_recv.read(N+Ng);
[timingCoarse.cp_off, timingCoarse.Nd, valid, timingCoarse.Z] = timing_coarse(x, N, Ng, Ng, timingCoarse.Z); if ~isempty(x)
if (valid) [timingCoarse.cp_off, timingCoarse.Nd, valid, timingCoarse.Z] = timing_coarse(x, N, Ng, Ng, timingCoarse.Z);
timingCoarse.cp_off_ = [timingCoarse.cp_off_ timingCoarse.cp_off]; if (valid)
if (timingCoarse.sync_counter > 0) timingCoarse.cp_off_ = [timingCoarse.cp_off_ timingCoarse.cp_off];
timingCoarse.sync_counter = timingCoarse.sync_counter - 1; if (timingCoarse.sync_counter > 0)
else timingCoarse.sync_counter = timingCoarse.sync_counter - 1;
timingCoarse.sync = 1; else
timingCoarse.sync = 1;
end
end;
if (timingCoarse.sync)
timingCoarse.cp_off = round(median(timingCoarse.cp_off_));
% Reset buffer to Cp offset
buf_recv.setReadIndex(timingCoarse.cp_off);
fprintf(' (cp_off=%d, Nd=%d)\n', timingCoarse.cp_off, timingCoarse.Nd);
end end
end;
if (timingCoarse.sync)
timingCoarse.cp_off = round(median(timingCoarse.cp_off_));
% Reset buffer to Cp offset
buf_recv.setReadIndex(timingCoarse.cp_off);
fprintf(' (cp_off=%d, Nd=%d)\n', timingCoarse.cp_off, timingCoarse.Nd);
end end
end end
@@ -285,8 +307,6 @@ while(fileRemain > fileChunkSize)
H_raw = zeros(length(carriers),1); H_raw = zeros(length(carriers),1);
fprintf('Channel estimation and symbol reception\n'); fprintf('Channel estimation and symbol reception\n');
figure(100);
end end
Z = transpose(buf_Z.read(N)); Z = transpose(buf_Z.read(N));
@@ -313,6 +333,7 @@ while(fileRemain > fileChunkSize)
% Get the correctly delayed symbols % Get the correctly delayed symbols
Z = buf_Z.readAt(N, -N*(symbols_to_delay+1)); Z = buf_Z.readAt(N, -N*(symbols_to_delay+1));
sym = Z(carrier_indexes).'; sym = Z(carrier_indexes).';
% Get the correctly delayed raw channel estimate % Get the correctly delayed raw channel estimate
@@ -368,7 +389,7 @@ while(fileRemain > fileChunkSize)
hold off; hold off;
pause(0.01); pause(0.01);
else elseif (equalizer.sync)
fac_c = fac_cell_list{mod(equalizer.s-symbols_to_delay, symbols_per_frame)+1}; fac_c = fac_cell_list{mod(equalizer.s-symbols_to_delay, symbols_per_frame)+1};
if (~isempty(fac_c)) if (~isempty(fac_c))
fac_i = fac_c - ofdm_spec_occ.kmin + 1; fac_i = fac_c - ofdm_spec_occ.kmin + 1;
@@ -387,11 +408,13 @@ while(fileRemain > fileChunkSize)
end end
end end
end end
% --------------------------------------------------------------
fileRemain = fileRemain - fileChunkSize; fileRemain = fileRemain - fileChunkSize;
fileCunkCounter = fileCunkCounter + 1; fileCunkCounter = fileCunkCounter + 1;
end end
% --------------------------------------------------------------
% Output
% --------------------------------------------------------------
figure; figure;
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}') 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}')
@@ -420,20 +443,32 @@ y = [a(3) a(4)];
plot(x-1,y, 'r-'); plot(x-1,y, 'r-');
hold off; hold off;
if 0 % --------------------------------------------------------------
% Write wave files
% --------------------------------------------------------------
fprintf('Writing wav files ');
buf_recv.setReadIndex(0);
x = buf_recv.read(buf_recv.len());
fprintf('.');
xout = [real(x) imag(x)]; xout = [real(x) imag(x)];
wavwrite(xout,fs,nbits,'rx_x.wav'); wavwrite(xout,fs,nbits,'rx_x.wav');
% Modulate on carrier % Modulate on carrier
fprintf('.');
xup = upsample(x, 4); xup = upsample(x, 4);
hlp = FIRCalcLowpass(0.25, 129); hlp = FIRCalcLowpass(0.25, 129);
fprintf('.');
xup = filter(hlp, 1, xup); xup = filter(hlp, 1, xup);
y = exp(j*2*pi.*(0:length(xup)-1)'*0.25) .* xup; y = exp(j*2*pi.*(0:length(xup)-1)'*0.25) .* xup;
wavwrite(y,fs4,nbits,'rx_y.wav'); fprintf('.');
wavwrite(y,4*fs,nbits,'rx_y.wav');
end fprintf(' done\n');
% --------------------------------------------------------------
function Y = spec_order(N, X) function Y = spec_order(N, X)
Y = [X(N/2+1:N)' X(1:N/2)']'; Y = [X(N/2+1:N)' X(1:N/2)']';