diff --git a/targets/ARCH/EXMIMO/USERSPACE/OCTAVE/OFDM_TX_FRAME.m b/targets/ARCH/EXMIMO/USERSPACE/OCTAVE/OFDM_TX_FRAME.m
index beea337f7b..35f2a39ce3 100755
--- a/targets/ARCH/EXMIMO/USERSPACE/OCTAVE/OFDM_TX_FRAME.m
+++ b/targets/ARCH/EXMIMO/USERSPACE/OCTAVE/OFDM_TX_FRAME.m
@@ -13,13 +13,13 @@ num_useful_carriers = num_carriers - num_zeros -1;
 sig = zeros(1,(num_carriers+prefix_length)*num_symbols_frame);
 sig_f = zeros(num_symbols_frame,num_useful_carriers);
 for k=1:preamble_length
-     QAM4_preamble = QAM_MOD(4,floor(4*abs(rand(1,num_useful_carriers))));
+     QAM4_preamble = QAM_MOD(4,floor(4*abs(rand(1,num_useful_carriers/4))));
      sig((k-1)*(num_carriers+prefix_length)+1:k*(num_carriers+prefix_length)) = OFDM_TX(num_carriers,num_zeros,prefix_length,QAM4_preamble);
      sig_f(k,:) = QAM4_preamble;
 end
 
 for k=preamble_length+1:num_symbols_frame
-     QAM_data = QAM_MOD(256,floor(4*abs(rand(1,num_useful_carriers))));
+     QAM_data = QAM_MOD(256,floor(256*abs(rand(1,num_useful_carriers/256))));
      sig((k-1)*(num_carriers+prefix_length)+1:k*(num_carriers+prefix_length)) = OFDM_TX(num_carriers,num_zeros,prefix_length,QAM_data);
      sig_f(k,:) = QAM_data;
 end
diff --git a/targets/ARCH/EXMIMO/USERSPACE/OCTAVE/txsig.m b/targets/ARCH/EXMIMO/USERSPACE/OCTAVE/txsig.m
index 201e68af07..d25837a145 100644
--- a/targets/ARCH/EXMIMO/USERSPACE/OCTAVE/txsig.m
+++ b/targets/ARCH/EXMIMO/USERSPACE/OCTAVE/txsig.m
@@ -40,7 +40,7 @@ oarf_config_exmimo(card, freq_rx,freq_tx,tdd_config,syncmode,rxgain,txgain,eNB_f
 amp = pow2(14)-1;
 n_bit = 16;
 
-length = pow2(2-resampling_factor(1));
+length = 307200/pow2(resampling_factor(1));
 
 s = zeros(length,4);
 
@@ -111,7 +111,8 @@ case 6
 
 otherwise 
   error('unknown case')
-endswitch
+
+end %switch
 
 s = s*2;