diff --git a/libraries/AP_AnalogSource/AP_AnalogSource_ADC.h b/libraries/AP_AnalogSource/AP_AnalogSource_ADC.h
index a438f00f40..c6807eaba1 100644
--- a/libraries/AP_AnalogSource/AP_AnalogSource_ADC.h
+++ b/libraries/AP_AnalogSource/AP_AnalogSource_ADC.h
@@ -9,7 +9,7 @@ class AP_AnalogSource_ADC : public AP_AnalogSource
 {
     public:
     AP_AnalogSource_ADC( AP_ADC * adc, int ch, float prescale = 1.0 ) :
-        _adc(adc), _ch(ch) {}
+        _adc(adc), _ch(ch), _prescale(prescale) {}
     int read(void);
 
     private:
diff --git a/libraries/AP_RangeFinder/AP_RangeFinder_MaxsonarXL.h b/libraries/AP_RangeFinder/AP_RangeFinder_MaxsonarXL.h
index 6dea8c63a9..6492bb2599 100644
--- a/libraries/AP_RangeFinder/AP_RangeFinder_MaxsonarXL.h
+++ b/libraries/AP_RangeFinder/AP_RangeFinder_MaxsonarXL.h
@@ -8,8 +8,6 @@
 
 class AP_RangeFinder_MaxsonarXL : public RangeFinder
 {
- // public:
-	//AP_GPS_MTK(Stream *s);
   public:
 	AP_RangeFinder_MaxsonarXL(AP_AnalogSource *source, ModeFilter *filter);
 
diff --git a/libraries/AP_RangeFinder/RangeFinder.h b/libraries/AP_RangeFinder/RangeFinder.h
index 8e930b0d05..5b08ce4723 100644
--- a/libraries/AP_RangeFinder/RangeFinder.h
+++ b/libraries/AP_RangeFinder/RangeFinder.h
@@ -18,9 +18,9 @@
 #define AP_RANGEFINDER_ORIENTATION_BACK_LEFT 	  5, -5,  0
 #define AP_RANGEFINDER_ORIENTATION_FRONT_LEFT 	  5,  5,  0
 */
-//#define AP_RANGEFINDER_PITOT_TUBE 1007
 
-//#define AP_RANGEFINDER_NUM_AVERAGES 4
+// define Pitot tube's ADC Channel
+#define AP_RANGEFINDER_PITOT_TYPE_ADC_CHANNEL 7
 
 class RangeFinder
 {