jens
b6e651271f
git-svn-id: http://moon:8086/svn/matlab/trunk@46 801c6759-fa7c-4059-a304-17956f83a07c
128 lines
2.9 KiB
Matlab
128 lines
2.9 KiB
Matlab
% function ofdm_tx(N_frames)
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function [yv xv] = ofdm_tx(mode, bandwidth, N_frames, withData, plot_speed)
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close all;
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DO_PLOT = (plot_speed > 0);
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WITH_RCWIN = 1;
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WITH_FREQ_REF = 1;
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WITH_TIME_REF = 1;
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WITH_GAIN_REF = 1;
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WITH_DATA = withData;
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DELAY = 100;
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M_QAM = 64;
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RCWIN_ROLLOFF = 0.125;
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% Params
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fa = 12000;
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T = 1/fa;
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[ofdm_params, ofdm_spec_occ] = drm_params(mode, bandwidth);
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ofdm_params_mode = ofdm_params.mode
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ofdm_spec_occ_kmin = ofdm_spec_occ.kmin
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ofdm_spec_occ_kmax = ofdm_spec_occ.kmax
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Tu = ofdm_params.nu * T
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Tg = ofdm_params.ng * T
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Ts = Tu+Tg
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Ng = round(Tg*fa)
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N = round(Tu*fa)
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Ns = round(Ts*fa)
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SubCarrierspacing_HZ = fa/N
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% TX window
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[rcwin Nt wng] = txwin_eval(N, Ng, RCWIN_ROLLOFF);
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Nt = Nt
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% Source
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qlut = qamtable(M_QAM);
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k_fft = sqrt(N);
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xv = zeros(1, DELAY);
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xt = zeros(1, Nt);
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x_prefix = zeros(2, Ng);
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x_suffix = zeros(2, Ng);
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ofdm_spec_occ.kmin
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ofdm_spec_occ.kmax
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sym_count = 0;
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for k=1:N_frames
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X = zeros(N,1);
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% Data
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if WITH_DATA == 1
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data_i = c2i(N, ofdm_spec_occ.kmin:1:ofdm_spec_occ.kmax);
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sym = round(M_QAM*rand(1, length(data_i))+0.5);
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X(data_i) = qlut(sym);
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end;
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if WITH_GAIN_REF == 1
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[ref_c ref_p ref_a] = getRefGain(ofdm_params, ofdm_spec_occ, sym_count);
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bins = c2i(N, ref_c);
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X(bins) = ref_a.*(exp(j*2*pi*ref_p/1024));
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end;
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if (sym_count==0) & (WITH_TIME_REF == 1)
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[ref_c ref_p ref_a] = getRefTime(ofdm_params.mode);
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bins = c2i(N, ref_c);
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X(bins) = ref_a.*(exp(j*2*pi*ref_p/1024));
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end;
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if WITH_FREQ_REF == 1
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[ref_c ref_p ref_a] = getRefFreq(ofdm_params.mode);
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bins = c2i(N, ref_c);
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X(bins) = ref_a.*(exp(j*2*pi*ref_p/1024));
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end;
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X(c2i(N, 0)) = 0;
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% Modulate
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xu = k_fft*ifft(X, N).';
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if WITH_RCWIN == 1
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x_prefix(1,:) = xu(N-Ng+1:N);
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x_suffix(1,:) = xu(1:Ng);
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x_pw = x_suffix(2,:) .* (1-wng) + x_prefix(1,:) .* wng;
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xs = [x_pw xu];
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x_prefix(2,:) = x_prefix(1,:);
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x_suffix(2,:) = x_suffix(1,:);
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else
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xs = [xu(N-Ng+1:N) xu];
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end;
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xv = [xv xs(1:Ng+N)];
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if (DO_PLOT == 1)
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% Xs = fftshift(fft(xs(Ng+1:Ng+N), N)/k_fft);
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Xs = fftshift(X);
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subplot(2, 1, 1)
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plot(0:N-1, abs(Xs(1:N)), '-*'); grid; axis([0 N-1 0 3.0]);
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subplot(2, 1, 2)
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plot(0:N-1, angle(Xs(1:N)), '-*'); grid; axis([0 N-1 -2*pi 2*pi]);
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pause(plot_speed);
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end
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sym_count = mod(sym_count+1, ofdm_params.nspf);
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end;
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hold off;
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grid;
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plot(wng); grid;
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% Modulate on carrier
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xup = upsample(xv, 4);
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hlp = FIRCalcLowpass(0.25, 129);
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xup = filter(hlp, 1, xup);
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yc = exp(j*2*pi.*(0:length(xup)-1)*0.25) .* xup;
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yv = real(yc) + imag(yc);
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xv = xv.' ./abs(max(xv));
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yv = yv'./max(yv);
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wavwrite(0.8*yv,4*fa,16,'yv.wav')
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wavwrite(0.8*[real(xv) imag(xv)],fa,16,'xv.wav')
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