Fixed detection of Code 11 (CCITT#5).

[lcr.git] / ss5_decode.c

diff --git a/ss5_decode.c b/ss5_decode.c
index 541f6be..0a00a6f 100644 (file)
--- a/ss5_decode.c
+++ b/ss5_decode.c
@@ -19,7 +19,7 @@
 #define NCOEFF         8       /* number of frequencies to be analyzed */
 
 #define MIN_DB         0.01995262 /* -17 db */
-#define DIFF_DB                0.31622777 /*  -5 db */
+#define DIFF_DB                0.2 // 0.31622777 /*  -5 db */
 #define SNR            1.3     /* noise may not exceed signal by that factor */
 
 /* For DTMF recognition:
@@ -56,7 +56,7 @@ char ss5_decode(unsigned char *data, int len)
        signed short buf[len];
        signed long sk, sk1, sk2, low, high;
        int k, n, i;
-       int f1 = 0, f2 = 0, f3 = 0;
+       int f1 = 0, f2 = 0;
        double result[NCOEFF], power, noise, snr;
        signed long long cos2pik_;
        char digit = ' ';
@@ -115,45 +115,33 @@ char ss5_decode(unsigned char *data, int len)
                        f2 = i;
                }
        }
-       power = 0.0;
-       for (i = 0; i < NCOEFF; i++) {
-               if (i != f1  && i != f2 && result[i] > power) {
-                       power = result[i];
-                       f3 = i;
-               }
-       }
 
-#if 0
-       /* check one frequency */
-       if (result[f1] > MIN_DB /* must be at least -17 db */
-        && result[f1]*DIFF_DB > result[f2]) /* must be 5 db above other tones */
-               digit = decode_one[f1];
-       /* check two frequencies */
-       if (result[f1] > MIN_DB && result[f2] > MIN_DB /* must be at lease -17 db */
-        && result[f1]*DIFF_DB <= result[f2] /* f2 must be not less than 5 db below f1 */
-        && result[f1]*DIFF_DB > result[f3]) /* f1 must be 5 db above other tones */
-               digit = decode_two[f1][f2];
-#endif
        snr = 0;
        /* check one frequency */
        if (result[f1] > MIN_DB /* must be at least -17 db */
         && result[f1]*SNR > noise) { /*  */
                digit = decode_one[f1];
-               snr = result[f1] / noise;
+               if (digit != ' ')
+                       snr = result[f1] / noise;
        }
        /* check two frequencies */
        if (result[f1] > MIN_DB && result[f2] > MIN_DB /* must be at lease -17 db */
         && result[f1]*DIFF_DB <= result[f2] /* f2 must be not less than 5 db below f1 */
         && (result[f1]+result[f2])*SNR > noise) { /* */
                digit = decode_two[f1][f2];
-               snr = (result[f1]+result[f2]) / noise;
+               if (digit != ' ')
+                       snr = (result[f1]+result[f2]) / noise;
        }
 
        /* debug powers */
 #ifdef DEBUG_LEVELS
-       for (i = 0; i < NCOEFF; i++)
-               printf("%d:%3d %c ", i, (int)(result[i]*100), (f1==i || f2==i)?'*':' ');
-       printf("N:%3d digit:%c snr=%3d\n", (int)(noise*100), digit, (int)(snr*100));
+       if (noise > 0.2) {
+               for (i = 0; i < NCOEFF; i++)
+                       printf("%d:%3d %c ", i, (int)(result[i]*100), (f1==i || f2==i)?'*':' ');
+               printf("N:%3d digit:%c snr=%3d\n", (int)(noise*100), digit, (int)(snr*100));
+               if (result[f1]*DIFF_DB <= result[f2]) /* f2 must be not less than 5 db below f1 */
+                       printf("jo!");
+       }
 #endif
 
        return digit;