altos/aprs: Encode last serial number in SSID. Transmit serial in comment

This makes it a lot easier to tell which device is sending
information, and to receive data from multiple devices on the same
receiver.

Signed-off-by: Keith Packard <keithp@keithp.com>

2 files changed, 4 insertions, 24 deletions

diff --git a/src/drivers/ao_aprs.c b/src/drivers/ao_aprs.c
index 8a1b6a4d..c33016f0 100644
--- a/src/drivers/ao_aprs.c
+++ b/src/drivers/ao_aprs.c
@@ -261,6 +261,7 @@ static uint8_t TNC_AX25_HEADER[] = {
 
 #define TNC_CALLSIGN_OFF	7
 #define TNC_CALLSIGN_LEN	6
+#define TNC_SSID_OFF		13
 
 static void
 tncSetCallsign(void)
@@ -275,6 +276,7 @@ tncSetCallsign(void)
 	}
 	for (; i < TNC_CALLSIGN_LEN; i++)
 		TNC_AX25_HEADER[TNC_CALLSIGN_OFF + i] = ' ' << 1;
+	TNC_AX25_HEADER[TNC_SSID_OFF] = 0x60 | ((ao_serial_number % 10) << 1);
 #endif
 }
 
@@ -530,6 +532,7 @@ static int tncComment(uint8_t *buf)
 #ifdef AO_SENSE_MAIN
 		       " M%d.%d"
 #endif
+		       " %d"
 		       , ao_gps_locked(),
 		       ao_num_sats(),
 		       battery/10,
@@ -542,6 +545,7 @@ static int tncComment(uint8_t *buf)
 		       , main/10,
 		       main%10
 #endif
+		       , ao_serial_number
 		);
 #else
 	return sprintf((char *) buf,
diff --git a/src/test/ao_aprs_test.c b/src/test/ao_aprs_test.c
index 86cf527a..573b5cb2 100644
--- a/src/test/ao_aprs_test.c
+++ b/src/test/ao_aprs_test.c
@@ -97,36 +97,12 @@ audio_gap(int secs)
 #endif
 }
 
-#include <math.h>
-
-int
-ao_aprs_encode_altitude_expensive(int meters)
-{
-	double	feet = meters / 0.3048;
-
-	double	encode = log(feet) / log(1.002);
-	return floor(encode + 0.5);
-}
-
 // This is where we go after reset.
 int main(int argc, char **argv)
 {
 	int	e, x;
 	int	a;
 
-	for (a = 1; a < 100000; a++) {
-		e = ao_aprs_encode_altitude(a);
-		x = ao_aprs_encode_altitude_expensive(a);
-
-		if (e != x) {
-			double	back_feet, back_meters;
-			back_feet = pow(1.002, e);
-			back_meters = back_feet * 0.3048;
-			fprintf (stderr, "APRS altitude encoding failure: altitude %d actual %d expected %d actual meters %f\n",
-				 a, e, x, back_meters);
-		}
-	}
-
     audio_gap(1);
 
     ao_gps_data.latitude = (45.0 + 28.25 / 60.0) * 10000000;