diff --git a/main/gen_gdl90.go b/main/gen_gdl90.go
index 75777086..c427a65d 100644
--- a/main/gen_gdl90.go
+++ b/main/gen_gdl90.go
@@ -211,7 +211,7 @@ func makeOwnshipReport() bool {
 		msg[12] = msg[12] | 0x0B // "Airborne" + "True Heading"
 	}
 
-	msg[13] = 0xBB // NIC and NACp.
+	msg[13] = byte(0x80 | (mySituation.NACp & 0x0F)) //Set NIC = 8 and use NACp from ry835ai.go.
 
 	gdSpeed := uint16(0) // 1kt resolution.
 	if isGPSGroundTrackValid() {
@@ -239,6 +239,15 @@ func makeOwnshipReport() bool {
 
 	msg[18] = 0x01 // "Light (ICAO) < 15,500 lbs"
 
+	// Create callsign "Stratux".
+	msg[19] = 0x53
+	msg[20] = 0x74
+	msg[21] = 0x72
+	msg[22] = 0x61
+	msg[23] = 0x74
+	msg[24] = 0x75
+	msg[25] = 0x78
+
 	sendGDL90(prepareMessage(msg), false)
 	return true
 }
@@ -737,7 +746,7 @@ func printStats() {
 		log.Printf("stats [up since: %s]\n", humanize.Time(timeStarted))
 		log.Printf(" - CPUTemp=%.02f deg C, MemStats.Alloc=%s, MemStats.Sys=%s, totalNetworkMessagesSent=%s\n", globalStatus.CPUTemp, humanize.Bytes(uint64(memstats.Alloc)), humanize.Bytes(uint64(memstats.Sys)), humanize.Comma(int64(totalNetworkMessagesSent)))
 		log.Printf(" - UAT/min %s/%s [maxSS=%.02f%%], ES/min %s/%s\n", humanize.Comma(int64(globalStatus.UAT_messages_last_minute)), humanize.Comma(int64(globalStatus.UAT_messages_max)), float64(maxSignalStrength)/10.0, humanize.Comma(int64(globalStatus.ES_messages_last_minute)), humanize.Comma(int64(globalStatus.ES_messages_max)))
-		log.Printf(" - Total traffic targets tracked=%s, last GPS fix: %s\n", humanize.Comma(int64(len(seenTraffic))), humanize.Time(mySituation.LastFixLocalTime))
+		log.Printf(" - Total traffic targets tracked=%s, last GPS fix: %s, GPS solution type: %d, NACp: %d, est accuracy %.02f m\n", humanize.Comma(int64(len(seenTraffic))), humanize.Time(mySituation.LastFixLocalTime), mySituation.quality, mySituation.NACp, mySituation.Accuracy)
 	}
 }
 
diff --git a/main/ry835ai.go b/main/ry835ai.go
index 334c1ca2..d58d2d68 100644
--- a/main/ry835ai.go
+++ b/main/ry835ai.go
@@ -31,6 +31,7 @@ type SituationData struct {
 	quality                 uint8
 	Satellites              uint16
 	Accuracy                float32 // Meters.
+	NACp                    uint8   // NACp categories are defined in AC 20-165A
 	Alt                     float32 // Feet.
 	alt_accuracy            float32
 	LastFixLocalTime        time.Time
@@ -266,7 +267,7 @@ func processNMEALine(l string) bool {
 		if err1 != nil {
 			return false
 		}
-		mySituation.quality = uint8(q)
+		mySituation.quality = uint8(q) // 1 = 3D GPS; 2 = DGPS (SBAS /WAAS)
 
 		// Satellites.
 		sat, err1 := strconv.Atoi(x[7])
@@ -280,7 +281,28 @@ func processNMEALine(l string) bool {
 		if err1 != nil {
 			return false
 		}
-		mySituation.Accuracy = float32(hdop * 5.0) //FIXME: 5 meters ~ 1.0 HDOP?
+		if mySituation.quality == 2 {
+			mySituation.Accuracy = float32(hdop * 4.0) //Estimate for WAAS / DGPS solution
+		} else {
+			mySituation.Accuracy = float32(hdop * 8.0) //Estimate for 3D non-WAAS solution
+		}
+
+		// NACp estimate.
+		if mySituation.Accuracy < 3 {
+			mySituation.NACp = 11
+		} else if mySituation.Accuracy < 10 {
+			mySituation.NACp = 10
+		} else if mySituation.Accuracy < 30 {
+			mySituation.NACp = 9
+		} else if mySituation.Accuracy < 92.6 {
+			mySituation.NACp = 8
+		} else if mySituation.Accuracy < 185.2 {
+			mySituation.NACp = 7
+		} else if mySituation.Accuracy < 555.6 {
+			mySituation.NACp = 6
+		} else {
+			mySituation.NACp = 0
+		}
 
 		// Altitude.
 		alt, err1 := strconv.ParseFloat(x[9], 32)