Abstract: A buoy is provided with first and second fixed hydrodynamic surfaces (15,16). When the buoy is towed through water by a tether (17), the first hydrodynamic surface (15) generates a downward force that reduces with increased speed through the water. The second hydrodynamic surface (16) generates an upward force that increases with increased speed through the water so that the buoy dives up to an upper critical speed through the water speed and rises beyond said upper critical speed through the water. The downward force of the first hydrodynamic surface (15) overcomes the buoyancy of the buoy at a lower critical speed through the water above, which the buoy dives. The hydrodynamic surface (15) comprises first fins (15) mounted on an outer casing (1) of the buoy and are spaced angularity and extend parallel to the center axis of the buoy which is substantially aligned with the direction of towing.

Abstract: A buoy is provided with first and second fixed hydrodynamic surfaces (15,16). When the buoy is towed through water by a tether (17), the first hydrodynamic surface (15) generates a downward force that reduces with increased speed through the water. The second hydrodynamic surface (16) generates an upward force that increases with increased speed through the water so that the buoy dives up to an upper critical speed through the water speed and rises beyond said upper critical speed through the water. The downward force of the first hydrodynamic surface (15) overcomes the buoyancy of the buoy at a lower critical speed through the water above, which the buoy dives. The hydrodynamic surface (15) comprises first fins (15) mounted on an outer casing (1) of the buoy and are spaced angularity and extend parallel to the centre axis of the buoy which is substantially aligned with the direction of towing.

Abstract: A method of providing an indication of the direction of a target such as a sniper. A rifle mounted sensor array detects an acoustic pulse originating from the target. The signal is processed to estimate the direction of the target, and an indication is provided when the weapon is aligned with the estimated direction. The direction of arrival of an acoustic pulse is estimated by spectrally decomposing each signal from the sensor so as to generate one or more spectral components for each signal, and processing the spectral components to estimate the direction of arrival.

Abstract: A method of providing an indication of the direction of a target such as a sniper. A rifle mounted sensor array detects an acoustic pulse originating from the target. The signal is processed to estimate the direction of the target, and an indication is provided when the weapon is aligned with the estimated direction. The direction of arrival of an acoustic pulse is estimated by spectrally decomposing each signal from the sensor so as to generate one or more spectral components for each signal, and processing the spectral components to estimate the direction of arrival.