% function ofdm_tx(N_frames)
function [yv xv] = ofdm_tx(N_frames)

WITH_DATA = 0;
WITH_FREQ_REF = 1;
WITH_TIME_REF = 1;

% Params
fa = 48000;
fc = fa/4;
F1 = 750;
F2 = 2250;
F3 = 3000;

SPEC_OCC_4k5 = 1;
SPEC_OCC_5k0 = 2;
SPEC_OCC_9k0 = 3;
SPEC_OCC_10k = 4;
SPEC_OCC_18k = 5;
SPEC_OCC_20k = 6;

DRM_MODE_A = 1;
DRM_MODE_B = 2;
DRM_MODE_C = 3;
DRM_MODE_D = 4;
DRM_MODE_E = 5;

ofdm_spec_occ_drm(DRM_MODE_A, SPEC_OCC_4k5) = struct('kmin',    2, 'kmax', 102);
ofdm_spec_occ_drm(DRM_MODE_A, SPEC_OCC_5k0) = struct('kmin',    2, 'kmax', 114);
ofdm_spec_occ_drm(DRM_MODE_A, SPEC_OCC_9k0) = struct('kmin', -102, 'kmax', 102);
ofdm_spec_occ_drm(DRM_MODE_A, SPEC_OCC_10k) = struct('kmin', -114, 'kmax', 114);
ofdm_spec_occ_drm(DRM_MODE_A, SPEC_OCC_18k) = struct('kmin', - 98, 'kmax', 314);
ofdm_spec_occ_drm(DRM_MODE_A, SPEC_OCC_20k) = struct('kmin', -110, 'kmax', 350);

ofdm_spec_occ_drm(DRM_MODE_B, SPEC_OCC_4k5) = struct('kmin',    1, 'kmax',  91);
ofdm_spec_occ_drm(DRM_MODE_B, SPEC_OCC_5k0) = struct('kmin',    1, 'kmax', 103);
ofdm_spec_occ_drm(DRM_MODE_B, SPEC_OCC_9k0) = struct('kmin', - 91, 'kmax',  91);
ofdm_spec_occ_drm(DRM_MODE_B, SPEC_OCC_10k) = struct('kmin', -103, 'kmax', 103);
ofdm_spec_occ_drm(DRM_MODE_B, SPEC_OCC_18k) = struct('kmin', - 87, 'kmax', 279);
ofdm_spec_occ_drm(DRM_MODE_B, SPEC_OCC_20k) = struct('kmin', - 99, 'kmax', 311);

ofdm_spec_occ_drm(DRM_MODE_C, SPEC_OCC_4k5) = struct('kmin',    0, 'kmax',   0);
ofdm_spec_occ_drm(DRM_MODE_C, SPEC_OCC_5k0) = struct('kmin',    0, 'kmax',   0);
ofdm_spec_occ_drm(DRM_MODE_C, SPEC_OCC_9k0) = struct('kmin',    0, 'kmax',   0);
ofdm_spec_occ_drm(DRM_MODE_C, SPEC_OCC_10k) = struct('kmin', - 69, 'kmax',  69);
ofdm_spec_occ_drm(DRM_MODE_C, SPEC_OCC_18k) = struct('kmin',    0, 'kmax',   0);
ofdm_spec_occ_drm(DRM_MODE_C, SPEC_OCC_20k) = struct('kmin', - 67, 'kmax', 213);

ofdm_spec_occ_drm(DRM_MODE_D, SPEC_OCC_4k5) = struct('kmin',    0, 'kmax',   0);
ofdm_spec_occ_drm(DRM_MODE_D, SPEC_OCC_5k0) = struct('kmin',    0, 'kmax',   0);
ofdm_spec_occ_drm(DRM_MODE_D, SPEC_OCC_9k0) = struct('kmin',    0, 'kmax',   0);
ofdm_spec_occ_drm(DRM_MODE_D, SPEC_OCC_10k) = struct('kmin', - 44, 'kmax',  44);
ofdm_spec_occ_drm(DRM_MODE_D, SPEC_OCC_18k) = struct('kmin',    0, 'kmax',   0);
ofdm_spec_occ_drm(DRM_MODE_D, SPEC_OCC_20k) = struct('kmin', - 43, 'kmax', 135);

ofdm_spec_occ_drm(DRM_MODE_E, SPEC_OCC_4k5) = struct('kmin', -106, 'kmax', 106);
ofdm_spec_occ_drm(DRM_MODE_E, SPEC_OCC_5k0) = struct('kmin',    0, 'kmax',   0);
ofdm_spec_occ_drm(DRM_MODE_E, SPEC_OCC_9k0) = struct('kmin',    0, 'kmax',   0);
ofdm_spec_occ_drm(DRM_MODE_E, SPEC_OCC_10k) = struct('kmin',    0, 'kmax',   0);
ofdm_spec_occ_drm(DRM_MODE_E, SPEC_OCC_18k) = struct('kmin',    0, 'kmax',   0);
ofdm_spec_occ_drm(DRM_MODE_E, SPEC_OCC_20k) = struct('kmin',    0, 'kmax',   0);

ofdm_params_drm(DRM_MODE_A) = struct('nu', 288, 'ng', 32, 'nspf', 15);
ofdm_params_drm(DRM_MODE_B) = struct('nu', 256, 'ng', 64, 'nspf', 15);
ofdm_params_drm(DRM_MODE_C) = struct('nu', 176, 'ng', 64, 'nspf', 20);
ofdm_params_drm(DRM_MODE_D) = struct('nu', 112, 'ng', 88, 'nspf', 24);
ofdm_params_drm(DRM_MODE_E) = struct('nu',  27, 'ng',  3, 'nspf', 40);

ofdm_params = ofdm_params_drm(DRM_MODE_B)
ofdm_spec_occ = ofdm_spec_occ_drm(DRM_MODE_B, SPEC_OCC_10k)

N_Carrier = 226;
M_qam = 4;
N_lp = 301;
T = 4/fa;
Tu = ofdm_params.nu * T
Tg = ofdm_params.ng * T
Ts = Tu+Tg
Ng = round(Tg*fa)
Nu = round(Tu*fa)
Ns = round(Ts*fa)
N_fft = Nu
SubCarrierspacing_HZ = fa/N_fft

% TX window
[txwin Nt] = txwin_eval(Nu, Ng, 0.05);

% Source
qlut = qamtable(M_qam);

% Band pass for transmission
f_lp = N_Carrier*fa/N_fft
hbp = cos(2*pi*(0:N_lp-1)*fc/fa).*sinc((-(N_lp-1)/2:(N_lp-1)/2)*f_lp/fa);
hbp = hbp/sum(hbp.^2).*Hanning(N_lp)';
hlp = sinc((-(N_lp-1)/2:(N_lp-1)/2)*f_lp/fa);
hlp = hlp/sum(hlp.^2).*Hanning(N_lp)';

k_fft = 2*sqrt(N_fft);
xv = [];
xt = zeros(1, Nt);

for k=1:N_frames
	for s=0:ofdm_params.nspf-1,
    
	    X = zeros(N_fft,1);
	    
		% 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));
    	end;
%    	X(78) = 0.20*qlut(round(M_qam*rand(1, 1)+0.5));

		if WITH_FREQ_REF == 1
		    [ref_i ref_p ref_a] = getRefFreq(N_fft, DRM_MODE_B, s);
		    X(ref_i) = 0.20*ref_a.*exp(-2*pi*i*ref_p/1024);
	   end;

		
		if (s==0) & (WITH_TIME_REF == 1)
		    [ref_i ref_p ref_a] = getRefTime(N_fft, DRM_MODE_B);
		    X(ref_i) = 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);
	    xv = [xv xs(1:Ng+Nu)];
	end;
end;

% Modulate on carrier
yc = 0.5*exp(-i*2*pi.*(0:length(xv)-1)*fc/fa) .* filter(hlp,1,xv);
yv = real(yc) + imag(yc);

xv = xv';
yv = yv';

% Output
close all;

figure;
freqz(hlp);

wavwrite(0.9*yv,fa,16,'yv.wav')
wavwrite(0.9*[real(xv) imag(xv)],fa,16,'xv.wav')

function index = c2i(N_fft, carriers)
	ri = [];
	ri = [ri find(carriers == 0)];
	carriers(ri) = [];
	index = mod(carriers, 1024) + 1;
		
function [ref_i ref_p ref_a] = getRefFreq(N_fft, drmMode, s)

ref_A_c = [18 54 72];
ref_A_p = [205 836 215];
ref_A_a = sqrt(2)*ones(1,3);


ref_B_c = [16 48 64];
ref_B_p = [331 651 555];
ref_B_a = sqrt(2)*ones(1,3);

ref_C_c = [11 33 44];
ref_C_p = [214 392 242];
ref_C_a = sqrt(2)*ones(1,3);

ref_D_c = [ 7 21 28];
ref_D_p = [788 1014 332];
ref_D_a = sqrt(2)*ones(1,3);

ref_E_c = [];
ref_E_p = [];
ref_E_a = [];

switch drmMode
	case 1
	ref_i = c2i(N_fft, ref_A_c);
	ref_p = ref_A_p;
	ref_a = ref_A_a;
	
	case 2
	ref_i = c2i(N_fft, ref_B_c);
	ref_p = ref_B_p;
	ref_a = ref_B_a;
	
	case 3
	ref_i = c2i(N_fft, ref_C_c);
	ref_p = ref_C_p;
	ref_a = ref_C_a;
	
	case 4
	ref_i = c2i(N_fft, ref_D_c);
	ref_p = ref_D_p;
	ref_a = ref_D_a;
	
	case 5
	ref_i = c2i(N_fft, ref_E_c);
	ref_p = ref_E_p;
	ref_a = ref_E_a;
end;

function [ref_i ref_p ref_a] = getRefTime(N_fft, drmMode)

ref_B_c = [14 18 20 24 26 32 36 42 44 49 50 54 56 62 66 68];
ref_B_p = [304 108 620 192 704 44 432 588 844 651 651 460 460 944 940 428];
ref_B_a = sqrt(2)*ones(1,16);

switch drmMode
	case 1
	ref_i = [];
	ref_p = [];
	ref_a = [];
	
	case 2
	ref_i = c2i(N_fft, ref_B_c);
	ref_p = ref_B_p;
	ref_a = ref_B_a;
	
	case 3
	ref_i = [];
	ref_p = [];
	ref_a = [];
	
	case 4
	ref_i = [];
	ref_p = [];
	ref_a = [];
	
	case 5
	ref_i = [];
	ref_p = [];
	ref_a = [];
end;

function [ref_i ref_p ref_a] = getRefGain(N_fft, spec_occ, drmMode, s)
switch drmMode
	case 1
	ref_c = [];
	ref_p = [];
	ref_a = [];
	
	case 2
	ref_c = 1 + 2*mod(s,3)+6*(spec_occ.kmin:1:spec_occ.kmax);
	ref_i = c2i(N_fft, ref_c);
	ref_p = ref_B_p;
	ref_a = sqrt(2)*ones(1,length(ref_i));
	
	case 3
	ref_c = [];
	ref_p = [];
	ref_a = [];
	
	case 4
	ref_c = [];
	ref_p = [];
	ref_a = [];
	
	case 5
	ref_c = [];
	ref_p = [];
	ref_a = [];
end;