From: drowe67 <drowe67@01035d8c-6547-0410-b346-abe4f91aad63>
Date: Thu, 30 Jan 2014 04:28:56 +0000 (+0000)
Subject: ldpc simulation working, but perf not that great in ccir poor 4dB channel
X-Git-Url: http://git.whiteaudio.com/gitweb/?a=commitdiff_plain;h=da899ae006db1b9745594fe78e3e84613b5ebb77;p=freetel-svn-tracking.git

ldpc simulation working, but perf not that great in ccir poor 4dB channel

git-svn-id: https://svn.code.sf.net/p/freetel/code@1394 01035d8c-6547-0410-b346-abe4f91aad63
---

diff --git a/codec2-dev/octave/fdmdv.m b/codec2-dev/octave/fdmdv.m
index a0b9b6a5..f64fe895 100644
--- a/codec2-dev/octave/fdmdv.m
+++ b/codec2-dev/octave/fdmdv.m
@@ -805,7 +805,9 @@ endfunction
 % then switch to a more robust tracking algorithm.  If we lose sync we switch
 % back to acquire mode for fast-requisition.
 
-function [track state bad_sync] = freq_state(sync_bit, state, bad_sync)
+function [entered_track track state bad_sync] = freq_state(sync_bit, state, bad_sync)
+
+  entered_track = 0;
 
   % acquire state, look for 6 symbol 010101 sequence from sync bit
 
@@ -845,6 +847,7 @@ function [track state bad_sync] = freq_state(sync_bit, state, bad_sync)
   end
   if state == 5
     if sync_bit == 1
+      entered_track = 1;
       next_state = 6;
       bad_sync = 0;
     else 
diff --git a/codec2-dev/octave/fdmdv_demod.m b/codec2-dev/octave/fdmdv_demod.m
index 2fe42702..dc553127 100644
--- a/codec2-dev/octave/fdmdv_demod.m
+++ b/codec2-dev/octave/fdmdv_demod.m
@@ -52,6 +52,8 @@ function fdmdv_demod(rawfilename, nbits, NumCarriers, errorpatternfilename, symb
   track = 0;
   fest_state = 0;
   bad_sync = 0;
+  sync_track = 0;
+  entered_track_log = [];
 
   % spectrum states
 
@@ -93,7 +95,7 @@ function fdmdv_demod(rawfilename, nbits, NumCarriers, errorpatternfilename, symb
     [foff_coarse S1 S2] = rx_est_freq_offset(rx_fdm, pilot, prev_pilot, nin);
     
     if track == 0
-      foff  = foff_coarse;
+      foff  = foff_coarse = 0;
     end
     foff_log = [ foff_log foff ];
     foff_rect = exp(j*2*pi*foff/Fs);
@@ -128,8 +130,17 @@ function fdmdv_demod(rawfilename, nbits, NumCarriers, errorpatternfilename, symb
 
     % optionally save output symbols 
 
-    if (nargin == 5) && (track == 1)
-      if sync == 1 
+    if (nargin == 5)
+
+      % this free runs, and is reset by an "entered sync" state
+
+      if (sync_track == 0)
+         sync_track = 1;
+      else
+         sync_track = 0; 
+      end
+
+      if (track == 1) && (sync_track == 1)
           dual_rx_symbols(Nc+1:2*Nc) = rx_symbols(1:Nc).*conj(prev_rx_symbols(1:Nc)./abs(prev_rx_symbols(1:Nc)));
           dual_rx_symbols_float32 = []; k = 1;
           for i=1:2*Nc
@@ -138,7 +149,7 @@ function fdmdv_demod(rawfilename, nbits, NumCarriers, errorpatternfilename, symb
           end
           fwrite(fm, dual_rx_symbols_float32, "float32");
           dual_rx_bits(Nc*Nb+1:2*Nc*Nb) = rx_bits;
-          dump_bits(dual_rx_bits);
+          %dump_bits(dual_rx_bits);
       else
           dual_rx_symbols(1:Nc) = rx_symbols(1:Nc).*conj(prev_rx_symbols(1:Nc)./abs(prev_rx_symbols(1:Nc)));
           dual_rx_bits(1:Nc*Nb) = rx_bits;
@@ -156,8 +167,12 @@ function fdmdv_demod(rawfilename, nbits, NumCarriers, errorpatternfilename, symb
 
     % freq est state machine
 
-    [track fest_state bad_sync] = freq_state(sync, fest_state, bad_sync);
+    [entered_track track fest_state bad_sync] = freq_state(sync, fest_state, bad_sync);
     track_log = [track_log track];
+    if (entered_track == 1)
+        sync_track = 1;
+    end
+    entered_track_log = [entered_track_log entered_track];
 
     % count bit errors if we find a test frame
 
@@ -196,6 +211,14 @@ function fdmdv_demod(rawfilename, nbits, NumCarriers, errorpatternfilename, symb
     test_frame_sync_log = [test_frame_sync_log test_frame_sync_state];
   end
  
+  if nargin == 5
+    fclose(fm);
+    etfilename = strcat(strtok(symbolfilename,"."),"_et.bin");
+    fet = fopen(etfilename, "wb");
+    fwrite(fet, entered_track_log, "short");
+    fclose(fet);
+  end
+
   % ---------------------------------------------------------------------
   % Print Stats
   % ---------------------------------------------------------------------
diff --git a/codec2-dev/octave/ldpc.m b/codec2-dev/octave/ldpc.m
index 2e9cf125..a8bbedbc 100644
--- a/codec2-dev/octave/ldpc.m
+++ b/codec2-dev/octave/ldpc.m
@@ -1,15 +1,5 @@
 % ldpc.m
-% ldpc functions
-
-% LDPC demo;   Bill Cowley 
-% Call the CML routines and simulate one set of SNRs.   See test_ldpc1.m
-%
-% sim_in the input parameter structure
-% sim_out contains BERs and other stats for each value of SNR
-% resfile is the result file
-%
-% 4/oct/2013:   edited to use the WiMax eIRA codes 
-%               see 'help InitializeWiMaxLDPC' for parameter values 
+% LDPC functions
 
 1;
 
@@ -42,7 +32,6 @@ function frameout = insert_uw(framein, uw)
     spacing = 2*lframein/luw;
 
     frameout = [];
-    mod_uw = [];
 
     pin = 1; pout = 1; puw = 1;
     while (luw)
@@ -51,7 +40,6 @@ function frameout = insert_uw(framein, uw)
         pin += spacing; 
         pout += spacing;
         frameout(pout:pout+1) = uw(puw:puw+1);
-        mod_uw(pout:pout+1) = qpsk_mod(uw(puw:puw+1));
         puw += 2;
         pout += 2;
         luw -= 2;
@@ -80,6 +68,29 @@ function frameout = remove_uw(framein, lvd, luw)
 endfunction
 
 
+% removes a unique word from a frame of symbols.  The UW symbols are spread
+% throughout the input frame 1 symbol at a time.
+
+function framesymbolsout = remove_uw_symbols(framesymbolsin, ldatasymbols, luwsymbols)
+
+    spacing = ldatasymbols/luwsymbols;
+
+    framesymbolsout = [];
+
+    pin = 1; pout = 1;
+    while (luwsymbols)
+        %printf("pin %d pout %d luw %d  ", pin, pout, luwsymbols);
+        %printf("pin+spacing-1 %d ldatasymbols %d lframein: %d\n", pin+spacing-1, ldatasymbols, length(framesymbolsin));
+        framesymbolsout(pout:pout+spacing-1) = framesymbolsin(pin:pin+spacing-1);
+        pin  += spacing + 1; 
+        pout += spacing;
+        luwsymbols--;
+    end
+
+endfunction
+
+
+
 % builds up a sparse QPSK modulated version version of the UW for use
 % in UW sync at the rx
 
@@ -166,3 +177,21 @@ function unpacked = unpackmsb(packed)
     end
 endfunction
 
+
+% symbol interleaver that acts on bits 2 at a time
+
+function y = interleave_bits(interleaver, x)
+    y =  zeros(1,length(x));
+    for i = 1:length(interleaver)
+        dst = interleaver(i);
+        y(2*(dst-1)+1:2*dst) = x(2*(i-1)+1:2*(i));
+    end
+endfunction
+
+% symbol de-interleaver
+
+function x = deinterleave_symbols(interleaver, y)
+    for i = 1:length(interleaver)
+        x(i) = y(interleaver(i));
+    end
+endfunction
diff --git a/codec2-dev/octave/ldpcdec.m b/codec2-dev/octave/ldpcdec.m
index 6e261cd1..91e89411 100644
--- a/codec2-dev/octave/ldpcdec.m
+++ b/codec2-dev/octave/ldpcdec.m
@@ -4,130 +4,192 @@
 % LDPC decoder test program, given a file of QPSK symbols (IQIQ floats), 
 % performs frame sync, decodes, and measures BER.
 
-% Start CML library
+function ldpcdec(filename)
 
-currentdir = pwd;
-addpath '/home/david/tmp/cml/mat'    % assume the source files stored here
-cd /home/david/tmp/cml
-CmlStartup                           % note that this is not in the cml path!
-cd(currentdir)
+  % Start CML library
 
-% Our LDPC library
+  currentdir = pwd;
+  addpath '/home/david/tmp/cml/mat'    % assume the source files stored here
+  cd /home/david/tmp/cml
+  CmlStartup                           % note that this is not in the cml path!
+  cd(currentdir)
 
-ldpc;
+  % Our LDPC library
 
-% Start simulation
+  ldpc;
 
-rand('state',1);
+  % Start simulation
 
-rate = 3/4; 
-framesize = 576;  
+  rand('state',1);
 
-mod_order = 4; 
-modulation = 'QPSK';
-mapping = 'gray';
+  rate = 3/4; 
+  framesize = 576;  
 
-demod_type = 0;
-decoder_type = 0;
-max_iterations = 100;
-EsNo = 10;
-Eprob = 0.0;
+  mod_order = 4; 
+  modulation = 'QPSK';
+  mapping = 'gray';
 
-vocoderframesize = 52;
-nvocoderframes = 8;
-nbitspermodemframe = 72;
+  demod_type = 0;
+  decoder_type = 0;
+  max_iterations = 100;
+  EsNo = 4;
+  Eprob = 0.0;
 
-code_param = ldpc_init(rate, framesize, modulation, mod_order, mapping);
-code_param.code_bits_per_frame = 576;
+  nbitspervocoderframe = 52;
+  nvocoderframes = 8;
+  nbitspermodemframe = 72;
 
-data = [];
-r = []; 
+  code_param = ldpc_init(rate, framesize, modulation, mod_order, mapping);
+  code_param.code_bits_per_frame = 576;
 
-Nframes = 100;
-uw = [1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0];
+  data = [];
+  r = []; 
+  load interleaver.txt
+  interleaver = interleaver + 1;
 
-% repeat same simulated vocoder data to ease testing
+  Nframes = 100;
+  uw = [1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0];
 
-vd = round( rand( 1, vocoderframesize*nvocoderframes) );
+  % repeat same simulated vocoder data to ease testing
 
-% Decoder: Sync with LDPC frames, LDPC decode, strip off UW, measure BER -------
+  vd = round( rand( 1, nbitspervocoderframe*nvocoderframes) );
 
-fm=fopen("modcodeword.bin","rb");
+  % Decoder: Sync with LDPC frames, de-interleave, LDPC decode, strip off UW, measure BER -------
 
-mod_uw = build_mod_uw(uw, 2*length(vd)/length(uw));
+  mcwfilename = strcat(filename,"_modcodeword.bin");
+  fm=fopen(mcwfilename,"rb");
+  etfilename = strcat(filename,"_et.bin");
+  fet=fopen(etfilename ,"rb");
+  epfilename = strcat(filename,".err");
+  fep=fopen(epfilename ,"wb");
+  printf("Input QPSK symbols: %s\n", mcwfilename);
+  if (fet == -1)
+    printf("Input entered track file: none\n");
+  else
+    printf("Input entered track file: %s\n", etfilename);
+  end
+  printf("Output error pattern file: %s\n", epfilename);
 
-mod_codeword = zeros(1, code_param.code_bits_per_frame/2);
-lmod_codeword = code_param.code_bits_per_frame/2;
+  mod_uw = build_mod_uw(uw, 2*length(vd)/length(uw));
 
-Terrs = 0; Ferrs = 0; Tbits = 0; Tframes = 0; nerr = [];
-corr = []; n = 0;
-sync_state = 0; sync_count = 0;
-mod_unpackedmodem_log = [];
+  mod_codeword = zeros(1, code_param.code_bits_per_frame/2);
+  lmod_codeword = code_param.code_bits_per_frame/2;
 
-[mod_unpackedmodem_float32, count] = fread(fm,nbitspermodemframe, "float32");
-while (count == nbitspermodemframe)
-    n++;
+  Terrs = 0; Ferrs = 0; Tbits = 0; Tframes = 0; nerr = [];
+  corr = []; n = 0;
+  sync_state = 0; sync_count = 0;
+  mod_unpackedmodem_log = [];
+  sync_state_log = [];
+  entered_track_log = [];
 
-    mod_unpackedmodem = mod_unpackedmodem_float32(1:2:nbitspermodemframe) + j*mod_unpackedmodem_float32(2:2:nbitspermodemframe);
-    mod_unpackedmodem_log = [mod_unpackedmodem_log mod_unpackedmodem];
-    erasures = rand(1,length(mod_unpackedmodem)) < Eprob; 
-    mod_unpackedmodem(erasures) = 0;
+  [mod_unpackedmodem_float32, count] = fread(fm,nbitspermodemframe, "float32");
+  if (fet == -1)
+      entered_track = 0;
+  else
+     entered_track = fread(fet, 1, "int");
+  end
 
-    % keep buffer of one entire codeword
+  while (count == nbitspermodemframe)
+      n++;
 
-    mod_codeword(1:lmod_codeword-length(mod_unpackedmodem)) = mod_codeword(length(mod_unpackedmodem)+1:lmod_codeword);
-    mod_codeword(lmod_codeword-length(mod_unpackedmodem)+1:lmod_codeword) = mod_unpackedmodem;
+      mod_unpackedmodem = mod_unpackedmodem_float32(1:2:nbitspermodemframe) + j*mod_unpackedmodem_float32(2:2:nbitspermodemframe);
+      mod_unpackedmodem_log = [mod_unpackedmodem_log mod_unpackedmodem];
+      erasures = rand(1,length(mod_unpackedmodem)) < Eprob; 
+      mod_unpackedmodem(erasures) = 0;
 
-    [uw_sync corr(n)] = look_for_uw(mod_codeword(1:length(mod_uw)), mod_uw);
-    if (uw_sync)
-      sync_state = 1;
-    end
+      % keep buffer of one entire codeword
 
-    if (sync_state && (sync_count == 0))
-        Tframes++;
+      mod_codeword(1:lmod_codeword-length(mod_unpackedmodem)) = mod_codeword(length(mod_unpackedmodem)+1:lmod_codeword);
+      mod_codeword(lmod_codeword-length(mod_unpackedmodem)+1:lmod_codeword) = mod_unpackedmodem;
 
-        % force UW symbols as they are known (is this needed?)
+      [uw_sync corr(n)] = look_for_uw(mod_codeword(1:length(mod_uw)), mod_uw);
 
-        % LDPC decode
+      next_sync_state = sync_state;
+      if ((sync_state == 0) && (uw_sync == 1))
+        next_sync_state = 1;
+        sync_count = 0;
+      end
+      if ((sync_state == 1) && (entered_track != 0))
+        next_sync_state = 0;
+      end
+      sync_state = next_sync_state;
+      sync_state_log = [sync_state_log sync_state];
+      entered_track_log = [entered_track_log entered_track];
 
-        detected_data = ldpc_dec(code_param, max_iterations, demod_type, decoder_type, mod_codeword, EsNo);
-
-        % unpack payload data, removing UW
-
-        vd_rx = remove_uw(detected_data(1:code_param.data_bits_per_frame), length(vd), length(uw));
-
-        % measure BER
-
-        error_positions = xor(vd, vd_rx);
-        Nerrs = sum(error_positions);
-        if Nerrs>0, fprintf(1,'x'); Ferrs++; ,  else fprintf(1,'.'),  end
-        Tbits += length(vd);
-        Terrs += Nerrs;
-        nerr(Tframes) = Nerrs;
-
-        % save packed payload data to disk
-    end
-
-    if (sync_state)
-        sync_count++;
-        if (sync_count == 8)
-            sync_count = 0;
-        end
-    end
-
-    % read in one modulated modem frame at a time
-
-    [mod_unpackedmodem_float32, count] = fread(fm, nbitspermodemframe, "float32");
-end
-
-fprintf(1,"\nFrames: %d bits: %d errors: %d BER = %f FER = %f\n", Tframes, Tbits, Terrs, Terrs/Tbits, Ferrs/Tframes);
-%subplot(211)
-%plot(corr);
-%subplot(212)
-%plot(nerr);
-figure(1)
-clf;
-[n m] = size(mod_unpackedmodem_log);
-plot( real(mod_unpackedmodem_log), imag(mod_unpackedmodem_log), '+')
-axis([-2 2 -2 2]);
-title('Scatter Diagram');
+      if (sync_state && (sync_count == 0))
+          Tframes++;
+
+          % remove UW symbols
+
+          mod_codeword_no_uw = remove_uw_symbols(mod_codeword, code_param.data_bits_per_frame/2 - length(uw)/2, length(uw)/2);
+          mod_codeword_no_uw = [mod_codeword_no_uw mod_codeword((code_param.data_bits_per_frame/2+1):code_param.code_bits_per_frame/2)];
+
+          % de-interleave
+
+          tmp = deinterleave_symbols(interleaver, mod_codeword_no_uw);
+        
+          % insert known symbols at end of data
+
+          mod_codeword_deinter = [ tmp(1:(code_param.data_bits_per_frame/2 - length(uw)/2)) ...
+                                 ones(1,length(uw)/2) * qpsk_mod([0 0]) ...
+                                 tmp((code_param.data_bits_per_frame/2 - length(uw)/2+1):length(tmp)) ];
+ 
+          % LDPC decode
+
+          detected_data = ldpc_dec(code_param, max_iterations, demod_type, decoder_type, mod_codeword_deinter, EsNo);
+
+          % unpack payload data, removing UW
+
+          vd_rx = detected_data(1:(code_param.data_bits_per_frame - length(uw)));
+
+          % measure BER
+
+          error_positions = xor(vd, vd_rx);
+          Nerrs = sum(error_positions);
+          if Nerrs>0, fprintf(1,'x'); Ferrs++; ,  else fprintf(1,'.'),  end
+          Tbits += length(vd);
+          Terrs += Nerrs;
+          nerr(Tframes) = Nerrs;
+
+          % save error patterns is simulated vocoder data to disk
+
+          fwrite(fep, error_positions, "short");
+          
+      end
+
+      if (sync_state)
+          sync_count++;
+          if (sync_count == 8)
+              sync_count = 0;
+          end
+      end
+
+      % read in one modulated modem frame at a time
+
+      [mod_unpackedmodem_float32, count] = fread(fm, nbitspermodemframe, "float32");
+      if (fet == -1)
+          entered_track = 0;
+      else
+          entered_track = fread(fet, 1, "int");
+      end
+  end
+
+  fclose(fep);
+
+  fprintf(1,"\nFrames: %d bits: %d errors: %d BER = %f FER = %f\n", Tframes, Tbits, Terrs, Terrs/Tbits, Ferrs/Tframes);
+
+  figure(8)
+  clf;
+  [n m] = size(mod_unpackedmodem_log);
+  plot( real(mod_unpackedmodem_log), imag(mod_unpackedmodem_log), '+')
+  axis([-2 2 -2 2]);
+  title('Scatter Diagram');
+
+  figure(9)
+  subplot(311)
+  plot(sync_state_log);
+  subplot(312)
+  plot(entered_track_log);
+  subplot(313)
+  plot(nerr);
+endfunction
diff --git a/codec2-dev/octave/ldpcenc.m b/codec2-dev/octave/ldpcenc.m
index 4a1e28f4..023c5172 100644
--- a/codec2-dev/octave/ldpcenc.m
+++ b/codec2-dev/octave/ldpcenc.m
@@ -1,172 +1,125 @@
 % ldpcenc.m
 % David Rowe 20 Dec 2013
 % 
-% LDPC encoder test program. Encodes and modulates a random data stream 
+% LDPC encoder function. Takes a random data pattern, LDPC Encodes and
+% inserts Unique Word (UW) sync bits and ouputs this as a packed
+% binary file suitable for the Nc=18 carrier FDMDV modulator,
+% fdmdv_mod.  Also produces a "modulated" output file of QPSK
+% symbols, suitable for feeding into ldpcdec for testing.
 
-% Start CML library
+function ldpcenc(filename)
 
-currentdir = pwd;
-addpath '/home/david/tmp/cml/mat'    % assume the source files stored here
-cd /home/david/tmp/cml
-CmlStartup                           % note that this is not in the cml path!
-cd(currentdir)
+  % Start CML library
 
-% Our LDPC library
+  currentdir = pwd;
+  addpath '/home/david/tmp/cml/mat'    % assume the source files stored here
+  cd /home/david/tmp/cml
+  CmlStartup                           % note that this is not in the cml path!
+  cd(currentdir)
+  
+  % Our LDPC library
 
-ldpc;
+  ldpc;
 
-% Start simulation
+  % Start simulation
 
-rand('state',1);
+  rand('state',1);
 
-rate = 3/4; 
-framesize = 576;  
+  rate = 3/4; 
+  framesize = 576;  
 
-mod_order = 4; 
-modulation = 'QPSK';
-mapping = 'gray';
+  mod_order = 4; 
+  modulation = 'QPSK';
+  mapping = 'gray';
 
-demod_type = 0;
-decoder_type = 0;
-max_iterations = 100;
-EsNo = 10;
-Eprob = 0.15;
+  demod_type = 0;
+  decoder_type = 0;
+  max_iterations = 100;
 
-vocoderframesize = 52;
-nvocoderframes = 8;
-nbitspermodemframe = 72;
+  nbitspervocoderframe = 52;
+  nvocoderframes = 8;
+  nbitspermodemframe = 72;
 
-code_param = ldpc_init(rate, framesize, modulation, mod_order, mapping);
+  code_param = ldpc_init(rate, framesize, modulation, mod_order, mapping);
 
-data = [];
-r = []; 
+  data = [];
+  r = []; 
+  load interleaver.txt
+  interleaver = interleaver + 1;
 
-% Encoder: Generate simulated vocoder data, insert UW, and LPDC encode ---------------
+  % Encoder: Generate simulated vocoder data
+  %          LPDC encode
+  %          interleave           
+  %          insert UW bits
 
-Nframes = 100;
-uw = [1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0];
+  Nframes = 100;
+  uw = [1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0];
 
-% repeat same simulated vocoder data to ease testing
+  % repeat same simulated vocoder data to ease testing
 
-vd = round( rand( 1, vocoderframesize*nvocoderframes) );
-d  = insert_uw(vd, uw);
+  vd = round( rand( 1, nbitspervocoderframe*nvocoderframes) );
 
-data = [data d];
-[codeword, s] = ldpc_enc(d, code_param);
-code_param.code_bits_per_frame = length(codeword);
-code_param.symbols_per_frame = length(s);
-packedcodeword = packmsb(codeword);
+  % pad data with zeros the size of UW
 
-fc=fopen("codeword.bin","wb");
-for nn = 1: Nframes        
-    fwrite(fc,packedcodeword,"uchar");
-end
-fclose(fc);
+  vdpad = [vd zeros(1, length(uw))];
 
-%printf("framesize: %d data_bits_per_frame: %d code_bits_per_frame: %d\n", ...
-%        framesize, code_param.data_bits_per_frame,  code_param.code_bits_per_frame);
+  % LDPC encode
 
-printf("Encoded %d LDPC frames\n", Nframes);
+  [codewordpad, s] = ldpc_enc(vdpad, code_param);
+  code_param.code_bits_per_frame = length(codewordpad);
+  code_param.symbols_per_frame = length(s);
 
-% Modulator: Modulate to QPSK symbols ------------------------------------------
+  % remove padded zeros after encoding to leave room for UW bits (code
+  % is systematic)
 
-lpackedcodeword=length(packedcodeword);
-fc=fopen("codeword.bin","rb");
-fm=fopen("modcodeword.bin","wb");
-lpackedmodem = nbitspermodemframe/8;
-n = 0;
+  codeword = [ codewordpad(1:length(vd)) codewordpad((length(vd)+length(uw)+1):length(codewordpad)) ];
 
-[packedmodem, count] = fread(fc,lpackedmodem,"uchar");
-while (count == lpackedmodem)
-    n++;
-    unpackedmodem = unpackmsb(packedmodem);
+  % interleave, insert UW bits, and pack bits (as C modulator likes packed bits)
 
-    ii = 1;
-    for i=1:2:length(unpackedmodem)
-        mod_unpackedmodem(ii) = qpsk_mod(unpackedmodem(i:i+1));
-        mod_unpackedmodem_float32(i) = real(mod_unpackedmodem(ii));
-        mod_unpackedmodem_float32(i+1) = imag(mod_unpackedmodem(ii));
-        ii += 1;
-    end
+  codeword_interleaved = interleave_bits(interleaver, codeword);
+  codeword_interleaved_uw = [insert_uw(codeword_interleaved(1:length(vd)), uw) codeword_interleaved(length(vd)+1:length(codeword_interleaved)) ];
+  packedcodeword = packmsb(codeword_interleaved_uw);
 
-    fwrite(fm, mod_unpackedmodem_float32, "float32");
-    [packedmodem, count] = fread(fc,lpackedmodem,"uchar");
-end
-fclose(fc);
-fclose(fm);
-printf("Modulated %d modem frames\n", n);
+  cwfilename = strcat(filename,"_codeword.bin");
+  fc=fopen(cwfilename,"wb");
+  for nn = 1: Nframes        
+      fwrite(fc,packedcodeword,"uchar");
+  end
+  fclose(fc);
 
+  %printf("framesize: %d data_bits_per_frame: %d code_bits_per_frame: %d\n", ...
+  %        framesize, code_param.data_bits_per_frame,  code_param.code_bits_per_frame);
 
-% Decoder: Sync with LDPC frames, LDPC decode, strip off UW, measure BER -------
+  printf("Encoded %d LDPC codewords, saved in packed file: %s\n", Nframes, cwfilename);
 
-fm=fopen("modcodeword.bin","rb");
+  % Modulator: Modulate to QPSK symbols ------------------------------------------
 
-mod_uw = build_mod_uw(uw, 2*length(vd)/length(uw));
+  nbytespackedcodeword=length(packedcodeword);
+  fc=fopen(cwfilename,"rb");
+  mcwfilename = strcat(filename,"_modcodeword.bin");
+  fm=fopen(mcwfilename,"wb");
+  nbytespackedmodemframe = nbitspermodemframe/8;
+  n = 0;
 
-mod_codeword = zeros(1, code_param.code_bits_per_frame/2);
-lmod_codeword = code_param.code_bits_per_frame/2;
+  [packedmodem, count] = fread(fc,nbytespackedmodemframe,"uchar");
+  while (count == nbytespackedmodemframe)
+      n++;
+      unpackedmodem = unpackmsb(packedmodem);
 
-Terrs = 0; Ferrs = 0; Tbits = 0; Tframes = 0; nerr = [];
-corr = []; n = 0;
-sync_state = 0; sync_count = 0;
+      ii = 1;
+      for i=1:2:length(unpackedmodem)
+          mod_unpackedmodem(ii) = qpsk_mod(unpackedmodem(i:i+1));
+          mod_unpackedmodem_float32(i) = real(mod_unpackedmodem(ii));
+          mod_unpackedmodem_float32(i+1) = imag(mod_unpackedmodem(ii));
+          ii += 1;
+      end
 
-[mod_unpackedmodem_float32, count] = fread(fm,nbitspermodemframe, "float32");
-while (count == nbitspermodemframe)
-    n++;
+      fwrite(fm, mod_unpackedmodem_float32, "float32");
+      [packedmodem, count] = fread(fc,nbytespackedmodemframe,"uchar");
+  end
+  fclose(fc);
+  fclose(fm);
+  printf("Modulated %d modem frames to file: %s\n", n, mcwfilename);
+endfunction
 
-    mod_unpackedmodem = mod_unpackedmodem_float32(1:2:nbitspermodemframe) + j*mod_unpackedmodem_float32(2:2:nbitspermodemframe);
-    erasures = rand(1,length(mod_unpackedmodem)) < Eprob; 
-    mod_unpackedmodem(erasures) = 0;
 
-    % keep buffer of one entire codeword
-
-    mod_codeword(1:lmod_codeword-length(mod_unpackedmodem)) = mod_codeword(length(mod_unpackedmodem)+1:lmod_codeword);
-    mod_codeword(lmod_codeword-length(mod_unpackedmodem)+1:lmod_codeword) = mod_unpackedmodem;
-
-    [uw_sync corr(n)] = look_for_uw(mod_codeword(1:length(mod_uw)), mod_uw);
-    if (uw_sync)
-      sync_state = 1;
-    end
-
-    if (sync_state && (sync_count == 0))
-        Tframes++;
-
-        % force UW symbols as they are known (is this needed?)
-
-        % LDPC decode
-
-        detected_data = ldpc_dec(code_param, max_iterations, demod_type, decoder_type, mod_codeword, EsNo);
-
-        % unpack payload data, removing UW
-
-        vd_rx = remove_uw(detected_data(1:code_param.data_bits_per_frame), length(vd), length(uw));
-
-        % measure BER
-
-        error_positions = xor(vd, vd_rx);
-        Nerrs = sum(error_positions);
-        if Nerrs>0, fprintf(1,'x'); Ferrs++; ,  else fprintf(1,'.'),  end
-        Tbits += length(vd);
-        Terrs += Nerrs;
-        nerr(Tframes) = Nerrs;
-
-        % save packed payload data to disk
-    end
-
-    if (sync_state)
-        sync_count++;
-        if (sync_count == 8)
-            sync_count = 0;
-        end
-    end
-
-    % read in one modulated modem frame at a time
-
-    [mod_unpackedmodem_float32, count] = fread(fm, nbitspermodemframe, "float32");
-end
-
-fprintf(1,"\nFrames: %d bits: %d errors: %d BER = %f FER = %f\n", Tframes, Tbits, Terrs, Terrs/Tbits, Ferrs/Tframes);
-subplot(211)
-plot(corr);
-subplot(212)
-plot(nerr);
diff --git a/codec2-dev/octave/pl2.m b/codec2-dev/octave/pl2.m
index 50d82262..17671c08 100644
--- a/codec2-dev/octave/pl2.m
+++ b/codec2-dev/octave/pl2.m
@@ -2,53 +2,40 @@
 % This program is distributed under the terms of the GNU General Public License 
 % Version 2
 
-function pl2(samname1, samname2, start_sam, end_sam, pngname)
+function pl2(samname1, samname2, start_sam, end_sam, offset)
   
   fs1=fopen(samname1,"rb");
   s1=fread(fs1,Inf,"short");
   fs2=fopen(samname2,"rb");
   s2=fread(fs2,Inf,"short");
 
-  st = 1;
-  en = length(s1);
+  st1 = st2 = 1;
+  en1 = en2 = length(s1);
   if (nargin >= 3)
-    st = start_sam;
+    st1 = st2 = start_sam;
   endif
   if (nargin >= 4)
-    en = end_sam;
+    en1 = en2 = end_sam;
+  endif
+
+  if (nargin == 5)
+    st2 += offset        
+    en2 += offset        
   endif
 
   figure(1);
   clf;
   subplot(211);
   l1 = strcat("r;",samname1,";");
-  plot(s1(st:en), l1);
-  axis([1 en-st min(s1(st:en)) max(s1(st:en))]);
+  plot(s1(st1:en1), l1);
+  axis([1 en1-st1 min(s1(st1:en1)) max(s1(st1:en1))]);
   subplot(212);
   l2 = strcat("r;",samname2,";");
-  plot(s2(st:en),l2);
-  axis([1 en-st min(s1(st:en)) max(s1(st:en))]);
+  plot(s2(st2:en2),l2);
+  axis([1 en2-st2 min(s1(st2:en2)) max(s1(st2:en2))]);
  
   figure(2)
-  plot(s1(st:en)-s2(st:en));
-  max(s1(st:en)-s2(st:en))
+  plot(s1(st1:en1)-s2(st2:en2));
   
-  if (nargin == 5)
-
-    % small image
-
-    __gnuplot_set__ terminal png size 420,300
-    s = sprintf("__gnuplot_set__ output \"%s.png\"", pngname);
-    eval(s)
-    replot;
-
-    % larger image
-
-    __gnuplot_set__ terminal png size 800,600
-    s = sprintf("__gnuplot_set__ output \"%s_large.png\"", pngname);
-    eval(s)
-    replot;
-
-  endif
 
 endfunction