unique word insertion for ldpc frame sync

git-svn-id: https://svn.code.sf.net/p/freetel/code@1347 01035d8c-6547-0410-b346-abe4f91aad63

diff --git a/codec2-dev/octave/ldpc.m b/codec2-dev/octave/ldpc.m
index addaafa659a7bf0e96ab4a5e6567fd66f4926c84..c00814786a0f9a451f6921cce0c1b8accb5c2c0e 100644 (file)
--- a/codec2-dev/octave/ldpc.m
+++ b/codec2-dev/octave/ldpc.m
@@ -20,6 +20,23 @@ function code_param = ldpc_init(rate, framesize, modulation, mod_order, mapping)
     code_param.bits_per_symbol = log2(mod_order);\r
 endfunction\r
 \r
+% inserts a unique word into a frame of bits\r
+\r
+function frameout = insert_uw(framein, uw)\r
+\r
+    luw = length(uw);\r
+    lframein = length(framein);\r
+    spacing = lframein/luw;\r
+\r
+    frameout = [];\r
+\r
+    for i=1:luw\r
+        frameout(1+(i-1)*spacing+i-1:i*spacing+i-1) = framein(1+(i-1)*spacing:i*spacing);\r
+        frameout(i*spacing+i) = uw(i);\r
+    end\r
+\r
+endfunction\r
+\r
 function [codeword s] = ldpc_enc(data, code_param)\r
         codeword = LdpcEncode( data, code_param.H_rows, code_param.P_matrix );\r
         s = Modulate( codeword, code_param.S_matrix );\r
@@ -39,53 +56,18 @@ function detected_data = ldpc_dec(code_param, max_iterations, demod_type, decode
     detected_data = x_hat(max_iterations,:);\r
 endfunction\r
 \r
-function sim_out = ldpc_proc(sim_in, resfile)\r
-\r
-    rate = 3/4; \r
-    framesize = 576;  \r
-\r
-    mod_order = 4; \r
-    modulation = 'QPSK';\r
-    mapping = 'gray';\r
-\r
-    demod_type = 0;\r
-    decoder_type = 0;\r
-    max_iterations = 100;\r
-\r
-    code_param = ldpc_init(rate, framesize, modulation, mod_order, mapping);\r
-\r
-    Ntrials = 84;\r
-    EsNo=10;\r
-\r
-    Tbits = Terrs = Ferrs = 0;\r
-    \r
-    data = [];\r
-    r = []; \r
-    for nn = 1: Ntrials        \r
-        d = round( rand( 1, code_param.data_bits_per_frame ) );\r
-        data = [data d];\r
-        [codeword, s] = ldpc_enc(d, code_param);\r
-        code_param.code_bits_per_frame = length(codeword);\r
-        code_param.symbols_per_frame = length(s);\r
-        r = [r s];\r
+% Packs a binary array into an array of 8 bit bytes, MSB first\r
+\r
+function packed = packmsb(unpacked)\r
+    packed = zeros(1,floor(length(unpacked)+7)/8);\r
+    bit = 7; byte = 1;\r
+    for i=1:length(unpacked)\r
+        packed(byte) = bitor(packed(byte), bitshift(unpacked(i),bit));\r
+        bit--;\r
+        if (bit < 0)\r
+            bit = 7;\r
+            byte++;\r
+        end \r
     end\r
-\r
-    for nn = 1: Ntrials        \r
-        st = (nn-1)*code_param.symbols_per_frame + 1;\r
-        en = (nn)*code_param.symbols_per_frame;\r
-        detected_data = ldpc_dec(code_param, max_iterations, demod_type, decoder_type, r(st:en), EsNo);\r
-        st = (nn-1)*code_param.data_bits_per_frame + 1;\r
-        en = (nn)*code_param.data_bits_per_frame;\r
-        error_positions = xor( detected_data(1:code_param.data_bits_per_frame), data(st:en) );\r
-        Nerrs = sum( error_positions);\r
-        \r
-        if Nerrs>0, fprintf(1,'x'),  else fprintf(1,'.'),  end\r
-        if (rem(nn, 50)==0),  fprintf(1,'\n'),  end    \r
-        if Nerrs>0,  Ferrs = Ferrs +1;  end\r
-        Terrs = Terrs + Nerrs;\r
-        Tbits = Tbits + code_param.data_bits_per_frame;        \r
-    end\r
-\r
 endfunction\r
 \r
-\r

diff --git a/codec2-dev/octave/ldpcenc.m b/codec2-dev/octave/ldpcenc.m
index 6c449272e8cabe34d461e2d9893d1b632e364e9a..0f8c5f9853d91461793c254fc5e0325868906727 100644 (file)
--- a/codec2-dev/octave/ldpcenc.m
+++ b/codec2-dev/octave/ldpcenc.m
@@ -1,50 +1,64 @@
-%test batch file   for the FSO-OOK simulations\r
+% ldpcenc.m\r
+% David Rowe 20 Dec 2013\r
 % \r
-% this version uses WiMax eIRA codes and includes erasures \r
+% LDPC encoder test program. Encodes and modulates a random data stream \r
 \r
-currentdir = pwd;\r
-thiscomp = computer;\r
+% Start CML library\r
 \r
+currentdir = pwd;\r
 addpath '/home/david/tmp/cml/mat'    % assume the source files stored here\r
 cd /home/david/tmp/cml\r
-CmlStartup              % note that this is not in the cml path!\r
-disp('added cluster path and run CmlStartup')\r
-\r
+CmlStartup                           % note that this is not in the cml path!\r
 cd(currentdir)\r
 \r
+% Our LDPC library\r
+\r
 ldpc;\r
 \r
-%\r
-%sim_in.Eprob = 0.1; \r
-%disp([' test with erasure probability of ' num2str(sim_in.Eprob)]); \r
+% Start simulation\r
+\r
+rate = 3/4; \r
+framesize = 576;  \r
+\r
+mod_order = 4; \r
+modulation = 'QPSK';\r
+mapping = 'gray';\r
+\r
+demod_type = 0;\r
+decoder_type = 0;\r
+max_iterations = 100;\r
+\r
+vocoderframesize = 52;\r
+nvocoderframes = 8;\r
+\r
+code_param = ldpc_init(rate, framesize, modulation, mod_order, mapping);\r
 \r
-%sim_in.comment = 'test ldpc';\r
-%sim_in.Esvec = 8:1/2:11; \r
+data = [];\r
+r = []; \r
 \r
-%sim_in.rate = 3/4;\r
-%sim_in.framesize = 16200\r
+% Encode a bunch of frames\r
 \r
-% sim_in.rate = 0.5;\r
-% sim_in.framesize = 204;\r
+Nframes = 100;\r
 \r
-sim_in.rate = 3/4; \r
-sim_in.framesize = 576;  \r
+% repeat same codeword frame for now to ease testing\r
 \r
-sim_in.mod_order = 4; \r
-sim_in.modulation = 'QPSK';\r
-sim_in.mapping = 'gray';\r
+vd = round( rand( 1, vocoderframesize*nvocoderframes) );\r
+d = insert_uw(vd, [1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0]);\r
 \r
-sim_in.Lim_Ferrs= 30;\r
-sim_in.Ntrials =  1000;\r
+data = [data d];\r
+[codeword, s] = ldpc_enc(d, code_param);\r
+code_param.code_bits_per_frame = length(codeword);\r
+code_param.symbols_per_frame = length(s);\r
+packedcodeword = packmsb(codeword);\r
 \r
+fc=fopen("codeword.bin","wb");\r
+for nn = 1: Nframes        \r
+    fwrite(fc,packedcodeword,"char");\r
+end\r
+fclose(fc);\r
 \r
-if exist('deb')~=1, deb = 0; end\r
-sim_in.deb =    deb;\r
+printf("framesize: %d data_bits_per_frame: %d code_bits_per_frame: %d\n", ...\r
+        framesize, code_param.data_bits_per_frame,  code_param.code_bits_per_frame);\r
 \r
-% init enc and dec\r
-% generate bits\r
-% encode\r
-% decode\r
-% measure BER\r
-ldpc_proc(sim_in, 'test.mat');\r
 \r
+ \r