From 0c864fd4dc31538a441c1e9692bda2bef86f31e2 Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <tridge@samba.org>
Date: Wed, 19 Sep 2012 15:28:43 +1000
Subject: [PATCH] AP_Airspeed: a bit more filtering

this helps reduce noise at low speed
---
 libraries/AP_Airspeed/AP_Airspeed.cpp | 3 +--
 libraries/AP_Airspeed/AP_Airspeed.h   | 2 --
 2 files changed, 1 insertion(+), 4 deletions(-)

diff --git a/libraries/AP_Airspeed/AP_Airspeed.cpp b/libraries/AP_Airspeed/AP_Airspeed.cpp
index 91a7f3c783..d5b805ee21 100644
--- a/libraries/AP_Airspeed/AP_Airspeed.cpp
+++ b/libraries/AP_Airspeed/AP_Airspeed.cpp
@@ -11,7 +11,6 @@
 #include <FastSerial.h>
 #include <AP_Common.h>
 #include <AP_Airspeed.h>
-#include <LowPassFilter.h>
 
 // table of user settable parameters
 const AP_Param::GroupInfo AP_Airspeed::var_info[] PROGMEM = {
@@ -71,5 +70,5 @@ void AP_Airspeed::read(void)
     }
     _airspeed_raw           = _source->read();
     airspeed_pressure       = max((_airspeed_raw - _offset), 0);
-    _airspeed               = sqrt(airspeed_pressure * _ratio);
+    _airspeed               = 0.7 * _airspeed + 0.3 * sqrt(airspeed_pressure * _ratio);
 }
diff --git a/libraries/AP_Airspeed/AP_Airspeed.h b/libraries/AP_Airspeed/AP_Airspeed.h
index 4b059b8fc8..a4b94217d5 100644
--- a/libraries/AP_Airspeed/AP_Airspeed.h
+++ b/libraries/AP_Airspeed/AP_Airspeed.h
@@ -6,8 +6,6 @@
 #include <AP_Common.h>
 #include <AP_Param.h>
 #include <AP_AnalogSource.h>
-#include <Filter.h>
-#include <AverageFilter.h>
 
 class AP_Airspeed
 {