From 069ebf37c7634d8f2ba25aab958de583320f08d6 Mon Sep 17 00:00:00 2001
From: davidbaker <david.baker@flightaware.com>
Date: Tue, 24 Mar 2015 12:05:38 -0500
Subject: [PATCH] Only send messages that have the LatLon updated.

Before we send messages if the LatLon or Altitude/Direction was updated. One of the values was stale.
Now the LatLon will be very accurate but the Altitude can be very stale.
---
 net_io.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/net_io.c b/net_io.c
index 7c35958..7a701e4 100644
--- a/net_io.c
+++ b/net_io.c
@@ -1025,7 +1025,7 @@ void modesReadFromClients(void) {
 
 void showFlightsFATSV(void) {
     struct aircraft *a = Modes.aircrafts;
-    time_t now = time(NULL);
+    time_t now = time(NULL), seen;
     int age, emittedSecondsAgo;
     static time_t lastTime = 0;
     char msg[TSV_BUFFER_SIZE], *p = msg;
@@ -1054,11 +1054,17 @@ void showFlightsFATSV(void) {
             continue;
         }
 
-        age = (int)(now - a->seen);
-        emittedSecondsAgo = (int)(now - a->fatsv_last_emitted);
+		// ADSB messages have seenLatLon set, Mode A/C never set seenLatLon
+		if (a->seenLatLon == 0) {
+			seen = a->seen;
+		} else {
+			seen = a->seenLatLon;
+		}
+		age = (int)(seen - a->fatsv_last_emitted);
+        emittedSecondsAgo = (int)(seen - a->fatsv_last_emitted);
 
         // don't emit if it hasn't updated since last time
-        if (age > emittedSecondsAgo) {
+        if (age == 0) {
             continue;
         }
 
@@ -1117,7 +1123,7 @@ void showFlightsFATSV(void) {
             }
         }
 
-        p += sprintf(p, "clock\t%ld\thexid\t%06X", a->seen, a->addr);
+        p += sprintf(p, "clock\t%ld\thexid\t%06X", seen, a->addr);
 
         // if ((a->bFlags & MODES_ACFLAGS_CALLSIGN_VALID) && *a->flight != '\0') {
         if (*a->flight != '\0') {
@@ -1173,7 +1179,7 @@ void showFlightsFATSV(void) {
 
         p += sprintf(p, "\n");
 
-        a->fatsv_last_emitted = now;
+        a->fatsv_last_emitted = seen;
         a->fatsv_emitted_altitude = alt;
         a->fatsv_emitted_track = a->track;