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- improved TX and RX

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git-svn-id: http://moon:8086/svn/matlab/trunk@5 801c6759-fa7c-4059-a304-17956f83a07c
This commit is contained in:
jens
2014-07-27 13:44:58 +00:00
parent 2e49c862b8
commit 1d2e8ce618
2 changed files with 35 additions and 137 deletions
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ofdm/ofdm_tx.m
+18 -17
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@@ -2,12 +2,14 @@
function [yv xv] = ofdm_tx(N_frames)
close all;
M_QAM = 4;
RC_ROLLOFF = 0.1;
WITH_RCWIN = 1;
WITH_DATA = 1;
WITH_FREQ_REF = 1;
WITH_TIME_REF = 0;
WITH_TIME_REF = 1;
M_QAM = 16;
RCWIN_ROLLOFF = 0.1;
% Params
fa = 48000;
@@ -80,11 +82,11 @@ Ts = Tu+Tg
Ng = round(Tg*fa)
Nu = round(Tu*fa)
Ns = round(Ts*fa)
N_fft = Nu
N_fft = Nu;
SubCarrierspacing_HZ = fa/N_fft
% TX window
[txwin Nt] = txwin_eval(Nu, Ng, RC_ROLLOFF);
[rcwin Nt] = txwin_eval(Nu, Ng, RCWIN_ROLLOFF);
% Source
qlut = qamtable(M_QAM);
@@ -102,7 +104,8 @@ for k=1:N_frames
% Data
if WITH_DATA == 1
data_i = c2i(N_fft, ofdm_spec_occ.kmin:1:ofdm_spec_occ.kmax);
X(data_i) = 0.20*qlut(round(M_QAM*rand(1, length(data_i))+0.5));
sym = round(M_QAM*rand(1, length(data_i))+0.5);
X(data_i) = 0.20*qlut(sym);
end;
% X(c2i(N_fft,65)) = 0.20*qlut(round(M_qam*rand(1, 1)+0.5));
@@ -117,13 +120,15 @@ for k=1:N_frames
X(c2i(N_fft, ref_c)) = 0.20*ref_a.*(exp(2*pi*i*ref_p/1024));
end;
% X(1) = 0.2;
% Modulate
xu = k_fft*ifft(X, N_fft)';
xs = [xu(Nu-Ng+1:Nu) xu xu(1:Nt)] .* txwin;
xs(1:Nt) = xs(1:Nt) + xt(1:Nt);
xt = xs(Ng+Nu+1:Ng+Nu+Nt);
if WITH_RCWIN == 1
xs = [xu(Nu-Ng+1:Nu) xu xu(1:Nt)] .* rcwin;
xs(1:Nt) = xs(1:Nt) + xt(1:Nt);
xt = xs(Ng+Nu+1:Ng+Nu+Nt);
else
xs = [xu(Nu-Ng+1:Nu) xu];
end;
xv = [xv xs(1:Ng+Nu)];
Xs = fft(xs(Ng+1:Ng+Nu), N_fft)/k_fft;
plot(fa*(0:N_fft/8-1)/N_fft, abs(Xs(1:N_fft/8)), '-*'); grid;
@@ -132,16 +137,12 @@ for k=1:N_frames
end;
% Modulate on carrier
yc = 0.5*exp(i*2*pi.*(0:length(xv)-1)*fc/fa) .* filter(hlp,1,xv);
yc = 0.5*exp(i*2*pi.*(0:length(xv)-1)*fc/fa) .* xv; %filter(hlp,1,xv);
yv = real(yc) + imag(yc);
xv = xv';
xv = conj(xv');
yv = yv';
% Output
figure;
freqz(hlp);
wavwrite(0.9*yv,fa,16,'yv.wav')
wavwrite(0.9*[real(xv) imag(xv)],fa,16,'xv.wav')