NXDN: Fix NXDN_LICH_OFFBITS and LICH_ERR_THRESHOLD to work as expected post NXDN Viterbi overhaul; Revert back to 1 bit error on lich "dividing";

NXDN: Skip Dibits prior to exit on bad sync in nxdn_frame;

NXDN: Reimplement the CAC fail demodulator and dibit buffer soft reset;

src/nxdn_deperm.c

@@ -591,6 +591,7 @@ void nxdn_facch1(dsd_opts * opts, dsd_state * state, uint8_t * bits)
 
 }
 
+static int cac_fail = 0;
 void nxdn_cac(dsd_opts * opts, dsd_state * state, uint8_t * bits)
 {
 
@@ -646,6 +647,10 @@ void nxdn_cac(dsd_opts * opts, dsd_state * state, uint8_t * bits)
 		fprintf (stderr, "%s", KNRM);
 	}
 
+	//check for accumulative cac failures and reset if multiple errors pile up
+	if (crc != 0) cac_fail++;
+	else cac_fail = 0;
+
 	if (crc == 0) NXDN_Elements_Content_decode(opts, state, 1, cac_message_buffer);
 
 	if (opts->payload == 1)
@@ -660,6 +665,45 @@ void nxdn_cac(dsd_opts * opts, dsd_state * state, uint8_t * bits)
 		if (crc != 0) fprintf (stderr, " CRC ERR ");
 
 	}
+
+	//reset some parameters if CAC continues to fail
+	if (cac_fail > 5)
+	{
+		//simple reset
+		state->synctype = -1; //was 0, which is p25p1
+		state->lastsynctype = -1;
+		state->carrier = 0;
+		state->last_cc_sync_time = time(NULL)+2; //probably not necesary
+		cac_fail = 0; //reset
+
+		//more advanced modulator reset
+		state->center = 0;
+		state->jitter = -1;
+		state->synctype = -1;
+		state->min = -15000;
+		state->max = 15000;
+		state->lmid = 0;
+		state->umid = 0;
+		state->minref = -12000;
+		state->maxref = 12000;
+		state->lastsample = 0;
+		for (int i = 0; i < 128; i++) state->sbuf[i] = 0;
+		state->sidx = 0;
+		for (int i = 0; i < 1024; i++) state->maxbuf[i] = 15000;
+		for (int i = 0; i < 1024; i++) state->minbuf[i] = -15000;
+		state->midx = 0;
+		state->symbolcnt = 0;
+
+		//reset the dibit buffer
+		state->dibit_buf_p = state->dibit_buf + 200;
+		memset (state->dibit_buf, 0, sizeof (int) * 200);
+		state->offset = 0;
+
+		//debug notification
+		// fprintf (stderr, " RESET CARRIER; ");
+
+	}
+
 }
 
 void idas_scch(dsd_opts * opts, dsd_state * state, uint8_t * bits, uint8_t direction)

src/nxdn_frame.c

@@ -13,7 +13,7 @@
 #include "dsd.h"
 #include "nxdn_const.h"
 
-#define LICH_ERR_THRESHOLD 2 //Threshold for lich dibit "dividing" errors
+#define LICH_ERR_THRESHOLD 7 //Threshold for lich dibit "dividing" errors (8 is perfect, 7 is 1 bit error)
 // #define NXDN_DEBUG_LICH      //print LICH debug info on err on payload == 1
 #define NXDN_LICH_OFFBITS    //use the offbits to help determine sync status (disable if bad signal / bad sample)
 
@@ -298,17 +298,17 @@ void nxdn_frame (dsd_opts * opts, dsd_state * state)
 			break;
 	} // end of switch(lich)
 
-	// //collect remaining dibits at this point (before bad frame skip)
-	// for (int i = 0; i < 174; i++) //192total-10FSW-8lich = 174
-	//  	dbuf[i+8] = getDibit(opts, state);
+	//collect remaining dibits at this point (before bad frame skip)
+	for (int i = 0; i < 174; i++) //192total-10FSW-8lich = 174
+	 	dbuf[i+8] = getDibit(opts, state);
 
 	//go to end if bad returns from earlier
 	if (state->lastsynctype == -1)
 		goto END;
 
-	//collect remaining dibits at this point (after bad frame skip)
-	for (int i = 0; i < 174; i++) //192total-10FSW-8lich = 174
-	 	dbuf[i+8] = getDibit(opts, state);
+	// //collect remaining dibits at this point (after bad frame skip)
+	// for (int i = 0; i < 174; i++) //192total-10FSW-8lich = 174
+	//  	dbuf[i+8] = getDibit(opts, state);
 
 	//enable these after good lich parity and known lich value
 	state->carrier = 1;

src/soft_viterbi_k5.c

@@ -19,7 +19,7 @@ static uint32_t prevMetrics[NUM_STATES];
 static uint32_t currMetrics[NUM_STATES];
 static uint32_t prevMetricsData[NUM_STATES];
 static uint32_t currMetricsData[NUM_STATES];
-static uint16_t viterbi_history[600];
+static uint16_t viterbi_history[600*2];
 
 /**
 * @brief Decode unpunctured convolutionally encoded data.
@@ -66,7 +66,7 @@ uint32_t viterbi_decode(uint8_t* out, const uint16_t* in, const uint16_t len)
 uint32_t viterbi_decode_punctured(uint8_t* out, const uint16_t* in, const uint8_t* punct, const uint16_t in_len, const uint16_t p_len)
 {
 
-	uint16_t umsg[400*2]; //unpunctured message
+	uint16_t umsg[600*2]; //unpunctured message
 	uint16_t p=0;		      //puncturer matrix entry
 	uint16_t u=0;		      //bits count - unpunctured message
 	uint16_t i=0;         //bits read from the input message