From 65fc129d883ced67d11cfb696cd94be6371b4930 Mon Sep 17 00:00:00 2001
From: Jens Ahrensfeld <jens@jayfield.org>
Date: Sun, 19 Apr 2015 20:06:40 +0000
Subject: [PATCH] - TX: process data at symbol rate - RX: removed kdown stuff
 (hardcode to 4), fixed redundant down sampling for base band processing

git-svn-id: http://moon:8086/svn/matlab/trunk@37 801c6759-fa7c-4059-a304-17956f83a07c
---
 ofdm/ofdm_rx.m | 19 +++++++++----------
 ofdm/ofdm_tx.m | 12 ++++++++----
 2 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/ofdm/ofdm_rx.m b/ofdm/ofdm_rx.m
index 0206746..cebea2a 100644
--- a/ofdm/ofdm_rx.m
+++ b/ofdm/ofdm_rx.m
@@ -5,25 +5,22 @@ function [x] = ofdm_rx(filename, foff, knoise_dB, with_cir)
 %          ofdm_rx('xv.wav', 0, -400, 0)
 %       or ofdm_rx('yv.wav', 0, -400, 0)
 
+close all;
+
 drm_mode = 'B';
 drm_bw = '10k';
 
 [ofdm_drm_params, ofdm_spec_occ] = drm_params(drm_mode, drm_bw);
 
-close all;
 pre_mix = 0;
-Kdown = 4;
-fs = 48000/Kdown;
-fc = fs/4;
-N = 1024/Kdown;
-Ng = 256/Kdown;
+fs = 12000;
+N = 256;
+Ng = 64;
 [carrier_pilot, phi_pilot, mag_pilot] = getRefFreq(drm_mode);
 [carrier_time, phi_time, mag_time] = getRefTime(drm_mode);
 
 h_cir = [0 0 .1 -.2 .5 .2 -.1 0 0 ];
 
-close all;
-
 % Generate signal
 [xwav fs_ nbits] = wavread(filename);
 
@@ -37,10 +34,12 @@ elseif (ndim == 1)
     x = xwav.*exp(-j*(2*pi*(0.25-foff/fs_)*(0:len-1)'));
     hlp = FIRCalcLowpass(12000/fs_, 33);
     x = filter(hlp, 1, x);
+	
+	% Downsample
+	x = x(1:4:length(x));
 else
     error('Cannot read file!');
 end
-x = x(1:Kdown:length(x));
 
 if with_cir
     x = filter(h_cir, 1, x);
@@ -53,7 +52,7 @@ wavwrite(xout,fs,nbits,'ofdm_rx.wav');
 x = x +  sqrt(0.5)*10^(knoise_dB/20)*(randn(size(x)) + j*randn(size(x)));
 
 
-K = fix((length(x)-Ng)/(N+Ng));
+K = fix((length(x))/(N+Ng))-1;
 
 % Timing coarse
 cp_off_ = [];
diff --git a/ofdm/ofdm_tx.m b/ofdm/ofdm_tx.m
index cb838d0..45df8d4 100644
--- a/ofdm/ofdm_tx.m
+++ b/ofdm/ofdm_tx.m
@@ -15,8 +15,8 @@ M_QAM = 64;
 RCWIN_ROLLOFF = 0.125;
 
 % Params
-fa = 48000;
-T = 4/fa;
+fa = 12000;
+T = 1/fa;
 
 [ofdm_params, ofdm_spec_occ] = drm_params(mode, bandwidth);
 
@@ -107,12 +107,16 @@ grid;
 plot(wng); grid;
 
 % Modulate on carrier
-yc = exp(j*2*pi.*(0:length(xv)-1)*0.25) .* xv;
+xup = upsample(xv, 4);
+hlp = FIRCalcLowpass(0.25, 129);
+xup = filter(hlp, 1, xup);
+
+yc = exp(j*2*pi.*(0:length(xup)-1)*0.25) .* xup;
 yv = real(yc) + imag(yc);
 
 xv = conj(xv')./abs(max(xv));
 yv = yv'./max(yv);
 
-wavwrite(0.9*yv,fa,16,'yv.wav')
+wavwrite(0.9*yv,4*fa,16,'yv.wav')
 wavwrite(0.9*[real(xv) imag(xv)],fa,16,'xv.wav')