Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a first user equipment (UE) may transmit, to a second UE via reflection by one or more passive devices, a first reference signal (RS) that is based at least in part on a shared first key that corresponds to a configuration of the one or more passive devices. The first UE may receive, from the second UE via reflection, a second RS that is based at least in part on the first key. The first UE may generate a second key based at least in part on a measurement of the second RS. The first UE may transmit a positioning reference signal that is based at least in part on the second key and that is associated with a measurement of a range between the first UE and the second UE. Numerous other aspects are described.

Techniques are discussed herein for analyzing radar data to determine that radar noise from one or more target detections potentially conceals additional objects near the target detection. Determining whether an object may be concealed can be based at least in part on a radar noise level based on a target detection, as well as distributions of radar cross sections and/or doppler data associated with particular object types. For a location near a target detection, a radar system may determine estimated noise levels, and compare the estimated noise levels to radar cross section probabilities associated with object types to determine the likelihood that an object of the object type could be concealed at the location. Based on the analysis, the system may determine a vehicle trajectory or otherwise may control a vehicle based on the likelihood that an object may be concealed at the location.

Techniques are discussed herein for analyzing radar data to determine that radar noise from one or more target detections potentially conceals additional objects near the target detection. Determining whether an object may be concealed can be based at least in part on a radar noise level based on a target detection, as well as distributions of radar cross sections and/or doppler data associated with particular object types. For a location near a target detection, a radar system may determine estimated noise levels, and compare the estimated noise levels to radar cross section probabilities associated with object types to determine the likelihood that an object of the object type could be concealed at the location. Based on the analysis, the system may determine a vehicle trajectory or otherwise may control a vehicle based on the likelihood that an object may be concealed at the location.

A system for using thin and energy-autonomous backscatter tags and corresponding sensing nodes may operate with 24 GHz backscatter reflectarray tags having low power consumption. A digital beam steering, frequency-modulated continuous wave (FMCW) radar may be used for detection, localization, identification and communications. The tags may include environmental sensors that are used to modulate backscatter waves for data communications directed to a reader or may digitally modulate the backscatter transmissions without sensor data for independent localization of each tag in a network.

An imaging apparatus includes: a reflector which covers an imaging space on a pathway that a human passes through, from at least one of both sides of the pathway, and diffusely reflects a sub-terahertz wave; a first light source which emits a sub-terahertz wave onto the reflector; and a first detector which receives a reflected wave of the sub-terahertz wave emitted from the first light source, diffusely reflected by the reflector, and reflected by the human, and generates an image based on the reflected wave received. The first light source and the first detector are located at a first direction side relative to a center of the imaging space in a direction in which the pathway extends.

An imaging apparatus includes: a reflector which covers an imaging space on a pathway that a human passes through, from at least one of both sides of the pathway, and diffusely reflects a sub-terahertz wave; a first light source which emits a sub-terahertz wave onto the reflector; and a first detector which receives a reflected wave of the sub-terahertz wave emitted from the first light source, diffusely reflected by the reflector, and reflected by the human, and generates an image based on the reflected wave received. The first light source and the first detector are located at a first direction side relative to a center of the imaging space in a direction in which the pathway extends.

Apparatuses, systems, methods, and software for train control and tracking using multi sensors, SSD/QR signs, and/or RF reflectors are disclosed, which enable determination of train location on a guideway, train movement authority, train length, and coupler status of each vehicle (married pair) and the consist (integrity) of the train.

Apparatus and associated methods relate to a method of non-contact motion detection. A one-dimensional optical sensor detects motion of a target or objects on a conveyor belt through a continuous measurement of targets or objects and a real-time comparison of the pixel images captured by the one-dimensional optical sensor. In an illustrative embodiment, a one-dimensional sensor may be configured to determine motion of objects based on changes to the captured intensities of pixel images over time. The sensor may continually capture photoelectric pixel images and compare a current pixel image with a previous pixel image to determine a frame differential image value. The frame differential image value is evaluated against a predetermined threshold over a predetermined time period. Based on the evaluation, a signal is output indicating whether the objects on the conveyor belt are moving or jammed.

Provided is a measurement device including: a reception strength measurement unit configured to measure reception strengths of radio signals which have difference frequencies and which are transmitted from a plurality of transmission devices; and a recording unit configured to sequentially record the reception strengths for the plurality of transmission devices.

Provided is a measurement device including: a reception strength measurement unit configured to measure reception strengths of radio signals which have difference frequencies and which are transmitted from a plurality of transmission devices; and a recording unit configured to sequentially record the reception strengths for the plurality of transmission devices.