geofence: can select gps instead of global position

src/modules/navigator/geofence_params.c

@@ -63,10 +63,23 @@ PARAM_DEFINE_INT32(GF_ON, 1);
  * Geofence altitude mode
  *
  * Select which altitude reference should be used
- * 0 = GPS, 1 = AMSL
+ * 0 = WGS84, 1 = AMSL
  *
  * @min 0
  * @max 1
  * @group Geofence
  */
-PARAM_DEFINE_INT32(GF_ALTMODE, 1);
+PARAM_DEFINE_INT32(GF_ALTMODE, 0);
+
+/**
+ * Geofence source
+ *
+ * Select which position source should be used. Selecting GPS instead of global position makes sure that there is
+ * no dependence on the position estimator
+ * 0 = global position, 1 = GPS
+ *
+ * @min 0
+ * @max 1
+ * @group Geofence
+ */
+PARAM_DEFINE_INT32(GF_SOURCE, 0);