From: drowe67 <drowe67@01035d8c-6547-0410-b346-abe4f91aad63>
Date: Mon, 16 Jan 2017 23:47:06 +0000 (+0000)
Subject: modified fsk get/put test frame utils so that they can re-sync on a continuous stream... 
X-Git-Url: http://git.whiteaudio.com/gitweb/?a=commitdiff_plain;h=c12bd9018e29298b70fb56bba13fd723386723ba;p=freetel-svn-tracking.git

modified fsk get/put test frame utils so that they can re-sync on a continuous stream, updated README examples

git-svn-id: https://svn.code.sf.net/p/freetel/code@2979 01035d8c-6547-0410-b346-abe4f91aad63
---

diff --git a/codec2-dev/README_fsk.txt b/codec2-dev/README_fsk.txt
index 7a3a2440..4638566f 100644
--- a/codec2-dev/README_fsk.txt
+++ b/codec2-dev/README_fsk.txt
@@ -18,24 +18,19 @@ Quickstart
 
 Built as part of codec2-dev, see README for build instructions.
 
-1. Using 10 test frames as a source of bits, generate 2FSK using a
-   8000 Hz sample rate, at 100 symbols/s (== 100 bit/s for 2FSK), with
-   two frequencies of 1200 and 2400 Hz, and stream via stdout to
-   "play" out speaker:
+1. Using 1000 test bits, generate 2FSK using a 8000 Hz sample rate, at
+   100 symbols/s (== 100 bit/s for 2FSK), with two frequencies of 1200
+   and 2400 Hz, and stream via stdout to "play" out speaker:
     
     $ cd build_linux/src
-    $ ./fsk_get_test_bits - 10 | ./fsk_mod 2 8000 100 1200 1200 - - | play -t raw -r 8000 -s -2 -
-
-    Each test frame has 400 bits, and the "fsk_get_test_bits"
-    generates 1+10=11 test frames in the example above - an extra
-    first frame is always generated to give the demod time to sync.
+    $ ./fsk_get_test_bits - 1000 | ./fsk_mod 2 8000 100 1200 1200 - - | play -t raw -r 8000 -s -2 -
 
     The low tone frequency is 1200Hz, and the upper tone 1200 + 1200 = 2400Hz.
 
-2. Measure the bit error rate of 100 frames of 100 bit/s 2FSK:
+2. Measure the bit error rate over 10,000 bits of 100 bit/s 2FSK:
 
-    $ ./fsk_get_test_bits - 100 | ./fsk_mod 2 8000 100 1200 100 - - | ./fsk_demod -l 2 8000 100 - - | ./fsk_put_test_bits -
-    FSK BER 0.000000, bits tested 39899, bit errors 0
+    $ ./fsk_get_test_bits - 10000 | ./fsk_mod 2 8000 100 1200 100 - - | ./fsk_demod -l 2 8000 100 - - | ./fsk_put_test_bits -
+    FSK BER 0.000000, bits tested 9800, bit errors 0
 
     In this example the two tones are at 1200 and 1200+100 = 1300Hz.
     A shift of 100Hz is the minimum possible for an incoherent FSK
@@ -46,11 +41,15 @@ Built as part of codec2-dev, see README for build instructions.
     is well suited to applications that can tolerate long latency, such
     as balloon telemetry.
 
-3. Measure the bit error rate of 100 frames at 1200 bits/s, using a
+    The demod and test frame logic takes a few frames to sync up, so
+    although we sent 10,000 bits, only 9800 are received.  However
+    there were no errors in those received bits.
+
+3. Measure the bit error rate of 5000 bits at 1200 bits/s, using a
    sample rate of 9600 Hz:
 
-    $ ./fsk_get_test_bits - 100 | ./fsk_mod 2 9600 1200 1200 1200 - - | ./fsk_demod -p 8 2 9600 1200 - - | ./fsk_put_test_bits -
-    FSK BER 0.000000, bits tested 39967, bit errors 0
+    $ ./fsk_get_test_bits - 5000 | ./fsk_mod 2 9600 1200 1200 1200 - - | ./fsk_demod -p 8 2 9600 1200 - - | ./fsk_put_test_bits -
+    FSK BER 0.000000, bits tested 4900, bit errors 0
 
     In this example, the -l and --lbr options are left out setting the modem
     up in "high speed" mode. In this mode, the demodulator operates on blocks of
@@ -70,6 +69,8 @@ Built as part of codec2-dev, see README for build instructions.
     P should be left alone unless CPU and memory usage needs to be lowered
     for the application.
 
+    (TODO, make this easier to understand, perhaps with figure)
+
 4.  (TODO High bit rate example like 115k project Horus)
 
 5. Automatically check C implementation against Octave using a variety of test conditions and 
diff --git a/codec2-dev/src/fsk_get_test_bits.c b/codec2-dev/src/fsk_get_test_bits.c
index 876b6205..fb26e2ed 100644
--- a/codec2-dev/src/fsk_get_test_bits.c
+++ b/codec2-dev/src/fsk_get_test_bits.c
@@ -2,7 +2,7 @@
 
   FILE........: fsk_get_test_bits.c
   AUTHOR......: Brady O'Brien
-  DATE CREATED: Januar 2016
+  DATE CREATED: January 2016
 
   Generates a pseudorandom sequence of bits for testing of fsk_mod and fsk_demod
 
@@ -30,65 +30,60 @@
 #include <stdio.h>
 #include <string.h>
 #include "fsk.h"
-#include "codec2_fdmdv.h"
 
-#define FSK_FRAME_SIZE 400
-#define INIT_SEQ {0,1,1,0,1,0,0,1,1,1,1,0,1,1,0,0,0,0,1,0,1,1,0,1,0,1,0,1,0,0,1,1}
-
-uint8_t init[] = INIT_SEQ;
+#define TEST_FRAME_SIZE 100  /* arbitrary chice, repeats after this
+                                many bits, sets frame size for rx
+                                processing */
 
 int main(int argc,char *argv[]){
-    int bitcnt;
-    int i,j;
+    int bitcnt, framecnt;
+    int i;
     FILE *fout;
     uint8_t *bitbuf;
     
-    
     if(argc != 3){
-        fprintf(stderr,"usage: %s OutputBitsOnePerByte FrameCount\n",argv[0]);
+        fprintf(stderr,"usage: %s OutputBitsOnePerByte numBits\n",argv[0]);
         exit(1);
     }
     
     /* Extract parameters */
     bitcnt = atoi(argv[2]);
-	
-	if(strcmp(argv[1],"-")==0){
-		fout = stdout;
-	}else{
-		fout = fopen(argv[1],"w");
-	}
+    framecnt = bitcnt/TEST_FRAME_SIZE;
+    if (framecnt == 0) {
+        fprintf(stderr,"Need a minimum of %d bits\n", TEST_FRAME_SIZE);
+        exit(1);
+    }
+
+    if(strcmp(argv[1],"-")==0){
+        fout = stdout;
+    }else{
+        fout = fopen(argv[1],"w");
+    }
     
     if(fout==NULL){
-        fprintf(stderr,"Couldn't open test vector files\n");
+        fprintf(stderr,"Couldn't open output file: %s\n", argv[1]);
         goto cleanup;
     }
     
     /* allocate buffers for processing */
-    bitbuf = (uint8_t*)alloca(sizeof(uint8_t)*FSK_FRAME_SIZE);
+    bitbuf = (uint8_t*)alloca(sizeof(uint8_t)*TEST_FRAME_SIZE);
     
-    /* Write out sync frame and sequence */
-    for(i=0; i<FSK_FRAME_SIZE; i++){
+    /* Generate buffer of test frame bits from known seed */
+    srand(158324);
+    for(i=0; i<TEST_FRAME_SIZE; i++){
 	bitbuf[i] = rand()&0x1;
     }
-    for(i=0;i<sizeof(init);i++){
-	bitbuf[FSK_FRAME_SIZE-sizeof(init)+i]=init[i];
-    }
-    fwrite(bitbuf,sizeof(uint8_t),FSK_FRAME_SIZE,fout);
-    
-    
-    /* Seed the RNG with some constant */
+        
+    /* Output test frames */
     srand(158324);
-    for(i=0; i<bitcnt; i++){
-	for(j=0; j<FSK_FRAME_SIZE; j++){
-		bitbuf[j] = rand()&0x1;
-	}
-	fwrite(bitbuf,sizeof(uint8_t),FSK_FRAME_SIZE,fout);
+    for(i=0; i<framecnt; i++){
+	fwrite(bitbuf,sizeof(uint8_t),TEST_FRAME_SIZE,fout);
 	if(fout == stdout){
 	    fflush(fout);
 	}
     }
     
-    cleanup:
+ cleanup:
     fclose(fout);
 
     return 0;
diff --git a/codec2-dev/src/fsk_put_test_bits.c b/codec2-dev/src/fsk_put_test_bits.c
index fc2fc221..f7e2273e 100644
--- a/codec2-dev/src/fsk_put_test_bits.c
+++ b/codec2-dev/src/fsk_put_test_bits.c
@@ -2,9 +2,10 @@
 
   FILE........: fsk_get_test_bits.c
   AUTHOR......: Brady O'Brien
-  DATE CREATED: Januar 2016
+  DATE CREATED: January 2016
 
-  Generates a pseudorandom sequence of bits for testing of fsk_mod and fsk_demod
+  Generates a pseudorandom sequence of bits for testing of fsk_mod and
+  fsk_demod.
 
 \*---------------------------------------------------------------------------*/
 
@@ -30,67 +31,72 @@
 #include <stdio.h>
 #include <string.h>
 #include "fsk.h"
-#include "codec2_fdmdv.h"
-
-#define FSK_FRAME_SIZE 100
-#define INIT_SEQ {0,1,1,0,1,0,0,1,1,1,1,0,1,1,0,0,0,0,1,0,1,1,0,1,0,1,0,1,0,0,1,1}
-
-uint8_t init[] = INIT_SEQ;
-uint8_t finit[sizeof(init)];
-
-int find_init(uint8_t next){
-	memmove(&finit[0],&finit[1],sizeof(init)-1);
-	finit[sizeof(init)-1] = next;
-	int i, err = 0;
-	for(i = 0;i<sizeof(init); i++){
-		if(init[i]!=finit[i]) err++;
-	}
-	return err<=3;
-}
+
+#define TEST_FRAME_SIZE 100  /* must match fsk_get_test_bits.c */
 
 int main(int argc,char *argv[]){
-    int bitcnt,bitcorr;
+    int bitcnt,biterr,i,errs;
     FILE *fin;
-    uint8_t bitbuf,cntbit;;
-    
-    /* Seed the RNG with some constant */
-    srand(158324);
+    uint8_t *bitbuf_tx, *bitbuf_rx, abit;
     
     if(argc != 2){
         fprintf(stderr,"usage: %s InputBitsOnePerByte \n",argv[0]);
         exit(1);
     }
     
-	
-	if(strcmp(argv[1],"-")==0 || argc<2){
-		fin = stdin;
-	}else{
-		fin = fopen(argv[1],"r");
-	}
+    if(strcmp(argv[1],"-")==0 || argc<2){
+        fin = stdin;
+    }else{
+        fin = fopen(argv[1],"r");
+    }
     
     if(fin==NULL){
-        fprintf(stderr,"Couldn't open test vector files\n");
+        fprintf(stderr,"Couldn't open input file: %s\n", argv[1]);
         goto cleanup;
     }
+
+    /* allocate buffers for processing */
+    bitbuf_tx = (uint8_t*)alloca(sizeof(uint8_t)*TEST_FRAME_SIZE);
+    bitbuf_rx = (uint8_t*)alloca(sizeof(uint8_t)*TEST_FRAME_SIZE);
+    
+    /* Generate known tx frame from known seed */
+    srand(158324);
+    for(i=0; i<TEST_FRAME_SIZE; i++){
+	bitbuf_tx[i] = rand()&0x1;
+	bitbuf_rx[i] = 0;
+    }
+    
     bitcnt = 0;
-    bitcorr = 0;
+    biterr = 0;
     
-    /* Find frame start word */
-    do{
-		fread(&bitbuf,sizeof(uint8_t),1,fin);
-	}while(!find_init(bitbuf));
-	
-	
-    while(fread(&bitbuf,sizeof(uint8_t),1,fin)>0){
-		cntbit = rand()&0x1;
-		if( (cntbit>0)==(bitbuf>0))
-			bitcorr++;
-		bitcnt++;
-		if(fin == stdin)
-			fflush(fin);
-	}
-	fprintf(stderr,"FSK BER %f, bits tested %d, bit errors %d\n",1-((float)bitcorr/(float)bitcnt),bitcnt,bitcnt-bitcorr);
+    while(fread(&abit,sizeof(uint8_t),1,fin)>0){
+
+        /* update silding window of input bits */
+
+        for(i=0; i<TEST_FRAME_SIZE-1; i++) {
+            bitbuf_rx[i] = bitbuf_rx[i+1];
+        }
+        bitbuf_rx[TEST_FRAME_SIZE-1] = abit;
+
+        /* compare to know tx frame.  If they are time aligned, there
+           will be a fairly low bit error rate */
+
+        errs = 0;
+        for(i=0; i<TEST_FRAME_SIZE; i++) {
+            if (bitbuf_rx[i] != bitbuf_tx[i]) {
+                errs++;
+            }
+        }
+        if (errs < 0.1*TEST_FRAME_SIZE) {
+            /* OK, we have a valid test frame sync, so lets count errors */
+            bitcnt += TEST_FRAME_SIZE;
+            biterr += errs;
+        }
+    }
+ 
+   fprintf(stderr,"FSK BER %f, bits tested %d, bit errors %d\n",
+           ((float)biterr/(float)bitcnt),bitcnt,biterr);
     
-    cleanup:
+ cleanup:
     fclose(fin);
 }