diff --git a/libraries/AP_GPS/AP_GPS.cpp b/libraries/AP_GPS/AP_GPS.cpp
index 55dd083b2b..e2a315b7ae 100644
--- a/libraries/AP_GPS/AP_GPS.cpp
+++ b/libraries/AP_GPS/AP_GPS.cpp
@@ -155,38 +155,38 @@ const AP_Param::GroupInfo AP_GPS::var_info[] = {
 
     // @Param: POS1_X
     // @DisplayName: Antenna X position offset
-    // @Description: X position of the first GPS antenna in body frame. Use antenna phase centroid location if provided by the manufacturer.
+    // @Description: X position of the first GPS antenna in body frame. Positive X is forward of the origin. Use antenna phase centroid location if provided by the manufacturer.
     // @Units: m
     // @User: Advanced
 
     // @Param: POS1_Y
     // @DisplayName: Antenna Y position offset
-    // @Description: Y position of the first GPS antenna in body frame. Use antenna phase centroid location if provided by the manufacturer.
+    // @Description: Y position of the first GPS antenna in body frame. Positive Y is to the right of the origin. Use antenna phase centroid location if provided by the manufacturer.
     // @Units: m
     // @User: Advanced
 
     // @Param: POS1_Z
     // @DisplayName: Antenna Z position offset
-    // @Description: Z position of the first GPS antenna in body frame. Use antenna phase centroid location if provided by the manufacturer.
+    // @Description: Z position of the first GPS antenna in body frame. Positive Z is down from the origin. Use antenna phase centroid location if provided by the manufacturer.
     // @Units: m
     // @User: Advanced
     AP_GROUPINFO("POS1", 16, AP_GPS, _antenna_offset[0], 0.0f),
 
     // @Param: POS2_X
     // @DisplayName: Antenna X position offset
-    // @Description: X position of the second GPS antenna in body frame. Use antenna phase centroid location if provided by the manufacturer.
+    // @Description: X position of the second GPS antenna in body frame. Positive X is forward of the origin. Use antenna phase centroid location if provided by the manufacturer.
     // @Units: m
     // @User: Advanced
 
     // @Param: POS2_Y
     // @DisplayName: Antenna Y position offset
-    // @Description: Y position of the second GPS antenna in body frame. Use antenna phase centroid location if provided by the manufacturer.
+    // @Description: Y position of the second GPS antenna in body frame. Positive Y is to the right of the origin. Use antenna phase centroid location if provided by the manufacturer.
     // @Units: m
     // @User: Advanced
 
     // @Param: POS2_Z
     // @DisplayName: Antenna Z position offset
-    // @Description: Z position of the second GPS antenna in body frame. Use antenna phase centroid location if provided by the manufacturer.
+    // @Description: Z position of the second GPS antenna in body frame. Positive Z is down from the origin. Use antenna phase centroid location if provided by the manufacturer.
     // @Units: m
     // @User: Advanced
     AP_GROUPINFO("POS2", 17, AP_GPS, _antenna_offset[1], 0.0f),