diff --git a/sw/airborne/subsystems/ins/ins_int_extended.h b/sw/airborne/subsystems/ins/ins_int_extended.h
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+++ b/sw/airborne/subsystems/ins/ins_int_extended.h
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+/*
+ * Copyright (C) 2008-2012 The Paparazzi Team
+ *
+ * This file is part of paparazzi.
+ *
+ * paparazzi is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * paparazzi is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with paparazzi; see the file COPYING.  If not, write to
+ * the Free Software Foundation, 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+/**
+ * @file subsystems/ins/ins_int_extended.h
+ *
+ * INS for rotorcrafts combining vertical and horizontal filters.
+ * This filter includes estimation of the baro drift based on sonar.
+ *
+ * Vertical filter is always enabled
+ *
+ * TODO: use GPS alt if good enough, especially when sonar readings are not available
+ *
+ */
+
+#ifndef INS_INT_EXTENDED_H
+#define INS_INT_EXTENDED_H
+
+#include "subsystems/ins.h"
+#include "std.h"
+#include "math/pprz_geodetic_int.h"
+#include "math/pprz_algebra_float.h"
+
+// TODO integrate all internal state to the structure
+///** Ins extended implementation state (fixed point) */
+//struct InsIntExtended {
+//};
+//
+///** global INS state */
+//extern struct InsInt ins_impl;
+
+/* gps transformed to LTP-NED  */
+extern struct LtpDef_i  ins_ltp_def;
+extern          bool_t  ins_ltp_initialised;
+extern struct NedCoor_i ins_gps_pos_cm_ned;
+extern struct NedCoor_i ins_gps_speed_cm_s_ned;
+
+/* barometer                   */
+extern int32_t ins_baro_alt;  ///< altitude calculated from baro in meters with #INT32_POS_FRAC
+extern int32_t ins_qfe;
+extern bool_t  ins_baro_initialised;
+#if USE_SONAR
+extern bool_t  ins_update_on_agl; /* use sonar to update agl if available */
+extern int32_t ins_sonar_offset;
+#endif
+
+/* output LTP NED               */
+extern struct NedCoor_i ins_ltp_pos;
+extern struct NedCoor_i ins_ltp_speed;
+extern struct NedCoor_i ins_ltp_accel;
+#if USE_HFF
+/* horizontal gps transformed to NED in meters as float */
+extern struct FloatVect2 ins_gps_pos_m_ned;
+extern struct FloatVect2 ins_gps_speed_m_s_ned;
+#endif
+
+/* copy position and speed to state interface */
+#define INS_NED_TO_STATE() {             \
+  stateSetPositionNed_i(&ins_ltp_pos);   \
+  stateSetSpeedNed_i(&ins_ltp_speed);    \
+  stateSetAccelNed_i(&ins_ltp_accel);    \
+}
+
+#endif /* INS_INT_EXTENDED_H */