The invention is a system that enables passive sonar identification of underwater items by making use of lift bags and/or flags, having distinctive sequences of bands of sonar-signal-reflecting materials, wherein the lift items are partially inflated so as to present a predictable orientation with respect to the floor of a body of water and its surface.

A sensor device may include a signal generator circuit configured to generate a supplemental signal that is combined with an ultrasonic reception voltage signal generated by an ultrasonic receiving element in response to received ultrasonic waves. The sensor device may comprise an ultrasonic receiving circuit configured to receive the combination of the ultrasonic reception voltage signal and the supplemental signal, and generate a detection signal that indicates when the space is occupied. The sensor device may also comprise a control circuit configured to receive the detection signal and detect an occupancy condition in the space in response to the detection signal. The combination of the supplemental signal with the ultrasonic reception voltage signal may ensure that the magnitudes of signals processed by the ultrasonic receiving circuit are large enough that the ultrasonic receiving circuit may appropriately generate the detection signal and the control circuit may detect the occupancy condition.

Techniques are disclosed for modifying the acoustic signature of plastic structures. An example structure implementing the techniques includes an inner wall forming an inner shell of the structure, the inner wall having a first edge and a second edge opposing the first edge, and an outer wall forming an outer shell of the structure, the outer wall having a first edge and a second edge opposing the first edge. The structure also includes an upper wall member joining the first edge of the inner wall to the first edge of the outer wall and a lower wall member joining the second edge of the inner wall to the second edge of the outer wall to form a wall cavity, an infill structure within the wall cavity, and at least two holes in the structure providing an opening from an exterior of the structure to the wall cavity.

A method is accordingly provided for operating an ultrasonic sensor, a plurality of measuring cycles being successively carried out. In each measuring cycle—an electroacoustic transducer of the ultrasonic sensor is excited using an excitation pulse, causing it to mechanically oscillate, as a result of which a measuring signal is transmitted by the transducer, an echo signal is received by the transducer, and a piece of object information is ascertained from the echo signal. The frequency curve of the excitation pulse is differentiated into two measuring cycles successively carried out at least at the end of the frequency curve. The ascertained pieces of object information from at least two measuring cycles are compared with one another and an interference is identified as a function of the result of the comparison.

A reception unit receives, with an ultrasonic sensor, received signals including a reflected wave obtained when an acoustic signal emitted from a mobile body is reflected by an object. A disturbance judgment unit judges whether a jamming attack in which a jamming signal is transmitted from outside is being made, on the basis of the received signals. An object detection unit detects an object in surroundings of the mobile body on the basis of the received signals if it is judged that no attack is being made and does not perform object detection if it is judged that an attack is being made.

A transmission circuit according to an embodiment includes: a plurality of constant current circuits, a plurality of switching elements, and controlling circuitry. The plurality of constant current circuits are connected in parallel to a power source line connected to a single power source and a transducer element. Each of the plurality of switching elements is connected to a different one of the plurality of constant current circuits and to the transducer element. The controlling circuitry is configured to control the plurality of switching elements on the basis of a waveform signal indicating a waveform of an ultrasound wave output from the transducer element.

A method for checking a distance measuring device of a transportation vehicle wherein the distance measuring device has ultrasonic sensors. A functional impairment of at least one ultrasonic sensor, a check is performed to determine whether one of the ultrasonic sensors is maladjusted, and an often occurring source of a fault causing a functional impairment of ultrasonic sensors is considered.

A method for automatically determining a potential transmission region, comprising: acquiring multiple binary indications for a direct line of sight between a transmitter and an airborne vehicle respective of multiple geo-positions of the airborne vehicle; acquiring each of the multiple geo-positions respective of each of the multiple binary indications for the direct line of sight; for each one of the acquired geo-positions, determining a layer of access respective of topographical data for the geographical region and the acquired geo-position, as a subset of the geographical region that includes at least one potential point defining a potential line of sight between the transmitter and the airborne vehicle, thereby determining multiple layers of access; determining an intersection of the multiple layers of access; and determining, from the intersection, the potential transmission region respective of the transmitter and the geo-positions of the airborne vehicle.

A method for automatically determining a potential transmission region, comprising: acquiring multiple binary indications for a direct line of sight between a transmitter and an airborne vehicle respective of multiple geo-positions of the airborne vehicle; acquiring each of the multiple geo-positions respective of each of the multiple binary indications for the direct line of sight; for each one of the acquired geo-positions, determining a layer of access respective of topographical data for the geographical region and the acquired geo-position, as a subset of the geographical region that includes at least one potential point defining a potential line of sight between the transmitter and the airborne vehicle, thereby determining multiple layers of access; determining an intersection of the multiple layers of access; and determining, from the intersection, the potential transmission region respective of the transmitter and the geo-positions of the airborne vehicle.

The invention is a system that enables passive sonar identification of underwater items by making use of lift bags and/or flags, having distinctive sequences of bands of sonar-signal-reflecting materials, wherein the lift items are partially inflated so as to present a predictable orientation with respect to the floor of a body of water and its surface.