diff --git a/farms/superTreefarm.lua b/farms/superTreefarm.lua
index 9b2e8dc..3611286 100644
--- a/farms/superTreefarm.lua
+++ b/farms/superTreefarm.lua
@@ -25,7 +25,6 @@ local GRID = {
 }
 
 local HOME_PT = { x = 0, y = 0, z = 0, heading = 0 }
-local HIGH_PT = { x = 0, y = 8, z = 0, heading = 0 }
 
 local DIG_BLACKLIST = {
   [ 'minecraft:furnace'     ] = true,
@@ -457,6 +456,7 @@ local function countSaplings()
 end
 
 local function randomSapling()
+  countSaplings()
   local sapling = ALL_SAPLINGS[math.random(1, #ALL_SAPLINGS)]
 
   if sapling.count > 0 then
diff --git a/gps/gpsServer.lua b/gps/gpsServer.lua
index 952eba6..f907015 100644
--- a/gps/gpsServer.lua
+++ b/gps/gpsServer.lua
@@ -1,4 +1,5 @@
 local Config = require('config')
+local GPS    = require('gps')
 local Util   = require('util')
 
 local args       = { ... }
@@ -6,11 +7,14 @@ local gps 			 = _G.gps
 local os         = _G.os
 local peripheral = _G.peripheral
 local turtle     = _G.turtle
+local vector     = _G.vector
 
 local WIRED_MODEM = 'computercraft:wired_modem_full'
 local CABLE       = 'computercraft:cable'
 local ENDER_MODEM = 'computercraft:advanced_modem'
 
+local positions = { }
+
 local function build()
 	if not turtle.has(WIRED_MODEM, 8) or
 		 not turtle.has(CABLE, 4) or
@@ -48,8 +52,18 @@ local function build()
 	end
 end
 
+local function memoize(t, k, fn)
+	local e = t[k]
+	if not e then
+		e = fn()
+		t[k] = e
+	end
+	return e
+end
+
 local function server()
 	local modems = Config.load('gpsServer')
+	local computers = { }
 
 	for k, modem in pairs(modems) do
 		Util.merge(modem, peripheral.wrap(k))
@@ -60,11 +74,27 @@ local function server()
 		local e, p1, p2, p3, p4, p5 = os.pullEvent( "modem_message" )
 		if e == "modem_message" then
 			-- We received a message from a modem
-			local sSide, sChannel, sReplyChannel, sMessage, nDistance = p1, p2, p3, p4, p5
-			if sChannel == gps.CHANNEL_GPS and sMessage == "PING" then
+			local sSide, channel, computerId, sMessage, distance = p1, p2, p3, p4, p5
+			if channel == gps.CHANNEL_GPS and sMessage == "PING" then
 				-- We received a ping message on the GPS channel, send a response
+				local computer = memoize(computers, computerId, function() return { } end)
+				local modem = modems[sSide]
+				table.insert(computer, {
+					position = vector.new(modem.x, modem.y, modem.z), distance = distance
+				})
+				if #computer == 4 then
+					local pt = GPS.trilaterate(computer)
+					if pt then
+						positions[computerId] = pt
+						term.clear()
+						for k,v in pairs(positions) do
+							Util.print('ID: %d: %s %s %s', k, v.x, v.y, v.z)
+						end
+					end
+					computers[computerId] = nil
+				end
 				for _, modem in pairs(modems) do
-					modem.transmit( sReplyChannel, gps.CHANNEL_GPS, { modem.x, modem.y, modem.z })
+					modem.transmit( computerId, gps.CHANNEL_GPS, { modem.x, modem.y, modem.z })
 				end
 			end
 		end