Improved data carrier detection

hardware/AFSK.c

@@ -61,6 +61,8 @@ void AFSK_init(Afsk *afsk) {
     AFSK_modem = afsk;
     // Set phase increment
     afsk->phaseInc = MARK_INC;
+    afsk->silentSamples = 0;
+
     // Initialise FIFO buffers
     fifo_init(&afsk->delayFifo, (uint8_t *)afsk->delayBuf, sizeof(afsk->delayBuf));
     fifo_init(&afsk->rxFifo, afsk->rxBuf, sizeof(afsk->rxBuf));
@@ -263,8 +265,12 @@ static bool hdlcParse(Hdlc *hdlc, bool bit, FIFOBuffer *fifo) {
     // If we have not yet seen a HDLC_FLAG indicating that
     // a transmission is actually taking place, don't bother
     // with anything.
-    if (!hdlc->receiving)
+    if (!hdlc->receiving) {
+        hdlc->dcd = false;
+        hdlc->dcd_count = 0;
+
         return ret;
+    }
 
     // First check if what we are seeing is a stuffed bit.
     // Since the different HDLC control characters like
@@ -312,6 +318,8 @@ static bool hdlcParse(Hdlc *hdlc, bool bit, FIFOBuffer *fifo) {
             } else {
                 // If it is, abort and return false
                 hdlc->receiving = false;
+                hdlc->dcd = false;
+                hdlc->dcd_count = 0;
                 LED_RX_OFF();
                 ret = false;
             }
@@ -324,6 +332,8 @@ static bool hdlcParse(Hdlc *hdlc, bool bit, FIFOBuffer *fifo) {
         } else {
             // If it is, well, you know by now!
             hdlc->receiving = false;
+            hdlc->dcd = false;
+            hdlc->dcd_count = 0;
             LED_RX_OFF();
             ret = false;
         }
@@ -338,7 +348,6 @@ static bool hdlcParse(Hdlc *hdlc, bool bit, FIFOBuffer *fifo) {
         hdlc->currentByte >>= 1;
     }
 
-    //digitalWrite(13, LOW);
     return ret;
 }
 
@@ -444,6 +453,9 @@ void AFSK_adc_isr(Afsk *afsk, int8_t currentSample) {
         } else {
             afsk->currentPhase -= PHASE_INC;
         }
+        afsk->silentSamples = 0;
+    } else {
+        afsk->silentSamples++;
     }
 
     // We increment our phase counter
@@ -513,6 +525,12 @@ void AFSK_adc_isr(Afsk *afsk, int8_t currentSample) {
         }
     }
 
+    if (afsk->silentSamples > DCD_TIMEOUT_SAMPLES) {
+        afsk->silentSamples = 0;
+        afsk->hdlc.dcd = false;
+        LED_RX_OFF();
+    }
+
 }
 
 

hardware/AFSK.h

@@ -53,6 +53,7 @@ inline static uint8_t sinSample(uint16_t i) {
 #define PHASE_INC    1                              // Nudge by an eigth of a sample each adjustment
 
 #define DCD_MIN_COUNT 6
+#define DCD_TIMEOUT_SAMPLES 96
                        
 #if BITRATE == 960
     #define FILTER_CUTOFF 600
@@ -107,6 +108,8 @@ typedef struct Afsk
     uint16_t phaseAcc;                      // Phase accumulator
     uint16_t phaseInc;                      // Phase increment per sample
 
+    uint8_t silentSamples;                 // How many samples were completely silent
+
     FIFOBuffer txFifo;                      // FIFO for transmit data
     uint8_t txBuf[CONFIG_AFSK_TX_BUFLEN];   // Actual data storage for said FIFO
 

main.c

@@ -41,7 +41,7 @@ void init(void) {
     sei();
 
     AFSK_init(&modem);
-    ax25_init(&AX25, &modem.fd, ax25_callback);
+    ax25_init(&AX25, &modem, &modem.fd, ax25_callback);
 
     serial_init(&serial);    
     stdout = &serial.uart0;

protocol/AX25.c

@@ -12,11 +12,13 @@
 #define DECODE_CALL(buf, addr) for (unsigned i = 0; i < sizeof((addr)); i++) { char c = (*(buf)++ >> 1); (addr)[i] = (c == ' ') ? '\x0' : c; }
 #define AX25_SET_REPEATED(msg, idx, val) do { if (val) { (msg)->rpt_flags |= _BV(idx); } else { (msg)->rpt_flags &= ~_BV(idx) ; } } while(0)
 
-void ax25_init(AX25Ctx *ctx, FILE *channel, ax25_callback_t hook) {
+void ax25_init(AX25Ctx *ctx, Afsk *modem, FILE *channel, ax25_callback_t hook) {
     memset(ctx, 0, sizeof(*ctx));
     ctx->ch = channel;
+    ctx->modem = modem;
     ctx->hook = hook;
     ctx->crc_in = ctx->crc_out = CRC_CCIT_INIT_VAL;
+    ctx->ready_for_data = true;
 }
 
 static void ax25_decode(AX25Ctx *ctx) {
@@ -93,6 +95,7 @@ void ax25_poll(AX25Ctx *ctx) {
         }
         ctx->escape = false;
     }
+
 }
 
 static void ax25_putchar(AX25Ctx *ctx, uint8_t c)
@@ -103,6 +106,7 @@ static void ax25_putchar(AX25Ctx *ctx, uint8_t c)
 }
 
 void ax25_sendRaw(AX25Ctx *ctx, void *_buf, size_t len) {
+    ctx->ready_for_data = false;
     ctx->crc_out = CRC_CCIT_INIT_VAL;
     fputc(HDLC_FLAG, ctx->ch);
     const uint8_t *buf = (const uint8_t *)_buf;
@@ -115,6 +119,7 @@ void ax25_sendRaw(AX25Ctx *ctx, void *_buf, size_t len) {
 
     fputc(HDLC_FLAG, ctx->ch);
 
+    ctx->ready_for_data = true;
 }
 
 #if SERIAL_PROTOCOL == PROTOCOL_SIMPLE_SERIAL

protocol/AX25.h

@@ -4,6 +4,7 @@
 #include <stdio.h>
 #include <stdbool.h>
 #include "device.h"
+#include "hardware/AFSK.h"
 
 #define AX25_MIN_FRAME_LEN 18
 #ifndef CUSTOM_FRAME_SIZE
@@ -30,6 +31,7 @@ struct AX25Msg;
 
 typedef struct AX25Ctx {
     uint8_t buf[AX25_MAX_FRAME_LEN];
+    Afsk *modem;
     FILE *ch;
     size_t frame_len;
     uint16_t crc_in;
@@ -37,6 +39,7 @@ typedef struct AX25Ctx {
     ax25_callback_t hook;
     bool sync;
     bool escape;
+    bool ready_for_data;
 } AX25Ctx;
 
 #if SERIAL_PROTOCOL == PROTOCOL_SIMPLE_SERIAL
@@ -68,6 +71,6 @@ typedef struct AX25Ctx {
 
 void ax25_poll(AX25Ctx *ctx);
 void ax25_sendRaw(AX25Ctx *ctx, void *_buf, size_t len);
-void ax25_init(AX25Ctx *ctx, FILE *channel, ax25_callback_t hook);
+void ax25_init(AX25Ctx *ctx, Afsk *modem, FILE *channel, ax25_callback_t hook);
 
 #endif

protocol/KISS.c

@@ -80,8 +80,7 @@ void kiss_csma(AX25Ctx *ctx, uint8_t *buf, size_t len) {
     }
 
     if (FLOWCONTROL) {
-        while (channel->sending_data) { /* Wait */ }
-
+        while (!ctx->ready_for_data) { /* Wait */ }
         fputc(FEND, &serial->uart0);
         fputc(CMD_READY, &serial->uart0);
         fputc(0x01, &serial->uart0);