A system to detect an occupant left in a vehicle includes a sensor, a determiner, and a controller. The sensor outputs a radio wave and detects a wave reflected by the occupant being left in the compartment. The determiner determines whether the occupant is left in the compartment, at least based on a detection result from the detected reflected wave. The controller selects a radio wave to be output from the sensor from those of different frequencies including a first radio wave a second radio wave lower in frequency than the first radio wave. The controller is configured to switch from the first radio wave to the second radio wave when the occupant is leaving the vehicle, and cause the determiner to determine whether the occupant is left, based on a detection result from the reflected wave detected by the sensor which output the second radio wave.

Provided is an array antenna divided into a plurality of sub-arrays disposed along a first dimension, wherein each sub-array comprises: a plurality of frequency scannable elements disposed along the first dimension and a plurality of phase shifters or transmit/receive (T/R) modules disposed along a second spatial dimension, each phase shifter or T/R module connected to a plurality of frequency scannable elements disposed along the first spatial dimension; and one or more processors being configured to generate a recurring radar waveform having a transmit portion, the transmit portion having multiple successive pulses at different frequencies to generate transmit beams by the array antenna at different angles in the first dimension; control at least one of the plurality of phase shifters or T/R modules along the second dimension to cause the transmit beams to be generated by the array antenna at different angles in the second dimension; and process return signals received by the plurality of sub-arrays to estimate a target location.

Provided is an array antenna divided into a plurality of sub-arrays disposed along a first dimension, wherein each sub-array comprises: a plurality of frequency scannable elements disposed along the first dimension and a plurality of phase shifters or transmit/receive (T/R) modules disposed along a second spatial dimension, each phase shifter or T/R module connected to a plurality of frequency scannable elements disposed along the first spatial dimension; and one or more processors being configured to generate a recurring radar waveform having a transmit portion, the transmit portion having multiple successive pulses at different frequencies to generate transmit beams by the array antenna at different angles in the first dimension; control at least one of the plurality of phase shifters or T/R modules along the second dimension to cause the transmit beams to be generated by the array antenna at different angles in the second dimension; and process return signals received by the plurality of sub-arrays to estimate a target location.

Techniques are provided for alerting a user of a virtual reality (VR) system of hazards in the proximate environment. An example method of proximity sensing with a virtual reality headset includes communicating with a station via a first wireless link, detecting a target object using radio frequency sensing on a second wireless link, determining a rate of approach associated with the target object, and generating an alert based at least in part on the rate of approach.

Techniques are provided for alerting a user of a virtual reality (VR) system of hazards in the proximate environment. An example method of proximity sensing with a virtual reality headset includes communicating with a station via a first wireless link, detecting a target object using radio frequency sensing on a second wireless link, determining a rate of approach associated with the target object, and generating an alert based at least in part on the rate of approach.

Object detection systems and methods are provided. An object detection system comprises a plurality of nodes, each node having a transmitter configured to transmit a radar signal as a beam, and one or more receivers configured to receive a reflected radar signal. The nodes and transmitters are arranged such that the radar beam of one transmitter at least partly overlaps with the radar beam from the transmitter at an adjacent one of the nodes. The object detection system comprises a processor configured to receive a digitised signal from each node, process the digitised signal to detect characteristics of any Doppler effects created by the movement of an object through one or more of the radar beams, compare the Doppler characteristics with Doppler signatures associated with known objects, and thereby classify the object.

A method for determining at least one object information item of at least one target object (18) which is sensed with a radar system (12), in particular of a vehicle (10), a radar system (12) and a driver assistance system (20) are described. In the method, transmission signals (32a, 32b) are transmitted into a monitoring range (14) of the radar system (12) with at least one transmitter (26a, 26b). Echoes, which are reflected at the at least one target object (18), of the transmission signals (32a, 32b) are received as received signals (34a, 34b) with at least one receiver (30), and if necessary are converted into a form which can be used by an electronic control and/or evaluation device (28). The received signals (34a, 34b) are subjected to at least one multi-dimensional discrete Fourier transformation. At least one target signal is determined from the result of the at least one Fourier transformation. At least one object information item is determined from the at least one target signal. At the transmitter end, at least one first transmission signal (32a) and at least one second transmission signal (32b) are generated from a frequency-modulated continuous wave signal. The at least one second transmission signal (32b) is encoded by means of phase modulation with respect to the at least one first transmission signal (32a), with the result that an at least temporary signal orthogonality between the at least one first transmission signal (32a) and the at least one second transmission signal (32b) is obtained. The at least one first transmission signal (32a) is emitted with at least one first transmitter (26a), and the at least one second transmission signal (32b) is emitted with at least one second transmitter (26b), simultaneously into the monitoring range (14) of the radar system (12). The at least one second transmission signal (32b) is emitted with regular transmission pauses of a predefined length.

A method for creating a virtual reception channel in a radar system includes an antenna possessing two physical reception channels (1.sub.r, 2.sub.r) spaced apart by a distance d in a direction x, two emission channels (1.sub.e, 2.sub.e) spaced apart by the same distance d in the same direction x and processing means, the method comprising: dynamically selecting two different waveforms, the waveforms being orthogonal to each other; generating a radar pulse of given central wavelength in each emission channel, each of the emission channels emitting one of the two different waveforms; acquiring with the reception channels echoes due to pulses emitted by the emission channels and reflected by at least one target; compressing the pulses by matched filtering of the echoes acquired by each physical reception channel, this involving correlating them with each of the waveforms generated in the emission channel; and repeating steps a) to c) while randomly changing one of the values of each of the phase codes associated with the generated waveforms until the level of the sidelobes of all the compressed pulses has stabilized; and radar system for implementing such a method.

According to one embodiment, a radar apparatus includes first antennas, a second antenna, and a third antenna. If the first antennas are used as transmission antennas, the second and third antennas are used as reception antennas. If the second and third antennas are used as the transmission antennas, the first antennas are used as the reception antennas. The first antennas are arranged in a first direction at a first distance and in a second direction crossing the first direction at a second distance. A distance between the second antenna and the third antenna in the first direction is approximately equal to a product of the first distance and a number of first antennas arranged in the first direction.

According to one embodiment, a radar apparatus includes first antennas, a second antenna, and a third antenna. If the first antennas are used as transmission antennas, the second and third antennas are used as reception antennas. If the second and third antennas are used as the transmission antennas, the first antennas are used as the reception antennas. The first antennas are arranged in a first direction at a first distance and in a second direction crossing the first direction at a second distance. A distance between the second antenna and the third antenna in the first direction is approximately equal to a product of the first distance and a number of first antennas arranged in the first direction.