add corner pegging

src/AprsService.scala

@@ -195,10 +195,10 @@ class AprsService extends Service with LocationListener {
 	}
 
 	def smartBeaconSpeedRate(speed : Float) : Int = {
-		val SB_FAST_SPEED = 14 // [m/s] = ~50km/h
+		val SB_FAST_SPEED = 28 // [m/s] = ~100km/h
 		val SB_FAST_RATE = 60
 		val SB_SLOW_SPEED = 1 // [m/s] = 3.6km/h
-		val SB_SLOW_RATE = 600
+		val SB_SLOW_RATE = 1200
 		if (speed <= SB_SLOW_SPEED)
 			SB_SLOW_RATE
 		else if (speed >= SB_FAST_SPEED)
@@ -207,14 +207,44 @@ class AprsService extends Service with LocationListener {
 			((SB_SLOW_RATE - SB_FAST_RATE) * (SB_FAST_SPEED - speed) / (SB_FAST_SPEED-SB_SLOW_SPEED)).toInt
 	}
 
+	// returns the angle between two bearings
+	def getBearingAngle(alpha : Float, beta : Float) : Float = {
+		val delta = math.abs(alpha-beta)%360
+		if (delta <= 180) delta else (360-delta)
+	}
+	// obtain max speed in [m/s] from moved distance, last and current location
+	def getSpeed(location : Location) : Float = {
+		val dist = location.distanceTo(lastLoc)
+		val t_diff = location.getTime - lastLoc.getTime
+		math.max(math.max(dist*1000/t_diff, location.getSpeed), lastLoc.getSpeed)
+	}
+
+	def smartBeaconCornerPeg(location : Location) : Boolean = {
+		if (!location.hasBearing || !lastLoc.hasBearing)
+			return false
+		val SB_TURN_TIME = 30
+		val SB_TURN_MIN = 10
+		val SB_TURN_SLOPE = 240.0
+		val t_diff = location.getTime - lastLoc.getTime
+		val turn = getBearingAngle(location.getBearing, lastLoc.getBearing)
+		// threshold depends on slope/speed [mph]
+		val threshold = SB_TURN_MIN + SB_TURN_SLOPE/(getSpeed(location)*2.23693629)
+
+		Log.d(TAG, "smartBeaconCornerPeg: %1.0f < %1.0f %d/%d".format(turn, threshold,
+			t_diff/1000, SB_TURN_TIME))
+		// need to corner peg if turn time reached and turn > threshold
+		(t_diff/1000 >= SB_TURN_TIME && turn > threshold)
+	}
+
 	// return true if current position is "new enough" vs. lastLoc
 	def smartBeaconCheck(location : Location) : Boolean = {
 		if (lastLoc == null)
 			return true
+		if (smartBeaconCornerPeg(location))
+			return true
 		val dist = location.distanceTo(lastLoc)
 		val t_diff = location.getTime - lastLoc.getTime
-		// obtain max speed from moved distance, last and current location
-		val speed = math.max(math.max(dist*1000/t_diff, location.getSpeed), lastLoc.getSpeed)
+		val speed = getSpeed(location)
 		//if (location.hasSpeed && location.hasBearing)
 		val speed_rate = smartBeaconSpeedRate(speed)
 		Log.d(TAG, "smartBeaconCheck: %1.0fm, %1.2fm/s -> %d/%ds - %s".format(dist, speed,