A process executes at an electronic system. The process identifies device characteristics of an imaging device that includes signal emitters and signal detectors. The process illuminates a field of view by signals from the signal emitters according to a modulation signal generated by the imaging device. At each of the signal detectors, the process obtains a response signal, and samples the response signals to form a response vector. The process obtains a lookup table corresponding to the modulation signal and the device characteristics. The field of view is partitioned into a 3-dimensional plurality of voxels, and the lookup table specifies, for each voxel, expected signals received by the signal detectors when the voxel is filled and the signal emitters illuminate the field of view according to the modulation signal. The process compares the response vector to the lookup table to determine which voxels are filled.

An alarm screen comprises a frame comprising a laser sensor, a processing unit, and a wireless transmitter embedded in a hollow interior. The frame comprises an opening for the laser sensor to project a laser beam outside of the alarm screen. The laser sensor projects the beam through the opening, makes a set of one or more measurements of a distance between the laser sensor and an object in a path of the laser beam, and sends the set of measurements to the processing unit. The processing unit is configured to compare the distance measurements received from the laser sensor with a threshold distance detect, and send one or more signals to the wireless transmitter when at least one of the distance measurements received from the laser sensor exceeds the threshold. The wireless transmitter is configured to receive signals from the processing unit and wirelessly transmit the signals.

A device may receive radio frequency (RF) transmissions from access points provided in a zone, and may calculate channel state information (CSI) for the access points based on the RF transmissions. The device may identify CSI phases that satisfy a phase threshold to eliminate surrounding movement in the zone and to focus on an entry location of the zone, and may perform a short-time Fourier transform of the CSI phases to generate a frequency versus time graph. The device may perform a spectrogram analysis of the frequency versus time graph or may process the frequency versus time graph, with a machine learning model, to determine a quantity of people in the zone and a start and stop times associated with entries and exits of the people to and from the zone. The device may perform actions based on the quantity of people and the start and stop times.

A device may receive radio frequency (RF) transmissions from access points provided in a zone, and may calculate channel state information (CSI) for the access points based on the RF transmissions. The device may identify CSI phases that satisfy a phase threshold to eliminate surrounding movement in the zone and to focus on an entry location of the zone, and may perform a short-time Fourier transform of the CSI phases to generate a frequency versus time graph. The device may perform a spectrogram analysis of the frequency versus time graph or may process the frequency versus time graph, with a machine learning model, to determine a quantity of people in the zone and a start and stop times associated with entries and exits of the people to and from the zone. The device may perform actions based on the quantity of people and the start and stop times.

In an embodiment, a children face alert system is provided for use with a smart device with a display screen. A neural network model trained with dataset images with embedded distance information can run in the background of the smart device. When receiving a captured image frame of the face of a child using the smart device, the neural network model can determine that the captured image frame is from a child, and further determine whether the face of the child is within a predetermined distance to the display screen based on a size of the face on the captured image frame. If the face is within the predetermined distance, the smart device can display an alert that the face of the child is too close to the display screen and pause one or more user applications until the child's face moves outside of the predetermined distance.

A three-dimensional (3D) sensor device achieves high intrusion detection probability while keeping the probability of a false intrusion detection low by capturing a set of multiple spatial or temporal samples of a measured parameter for an object detected in the sensor's field of view. When an object is detected in the field of view, the TOF sensor device defines a window of N pixels comprising a subset of the pixels corresponding to the object, and obtains N distance measurements corresponding to the N pixels of the window. If the number of the N distance values that are less than a defined threshold distance is equal to or greater than a selected threshold value M (an integer less than N), the TOF sensor device determines that the object is intruding within a protective field and generates a suitable output.

A system, including: a radar including a transmitter and a receiver, the transmitter configured to transmit an electromagnetic wave; a reflector placed a predetermined distance away from the radar, the reflector configured to reflect the transmitted electromagnetic wave back to the receiver; and a control unit coupled to the radar and configured to measure a magnitude of the reflected electromagnetic wave received at the receiver from the reflector by measuring Doppler signal corresponding to the predetermined distance, wherein the control unit is configured to measure a reference value of the magnitude of the reflected electromagnetic wave when no intrusions are occurring, and wherein the control unit is configured to trigger an alarm when the magnitude of the reflected electromagnetic wave changes from the reference value.

An intrusion detection system and method are provided. The intrusion detection system may be configured to detect an intruder or authorized person in an area based on light-based feedback and absence of wireless communications with a remote device.

A system, including: a radar including a transmitter and a receiver, the transmitter configured to transmit an electromagnetic wave; a reflector placed a predetermined distance away from the radar, the reflector configured to reflect the transmitted electromagnetic wave back to the receiver; and a control unit coupled to the radar and configured to measure a magnitude of the reflected electromagnetic wave received at the receiver from the reflector by measuring Doppler signal corresponding to the predetermined distance, wherein the control unit is configured to measure a reference value of the magnitude of the reflected electromagnetic wave when no intrusions are occurring, and wherein the control unit is configured to trigger an alarm when the magnitude of the reflected electromagnetic wave changes from the reference value.

In an embodiment, a children face alert system is provided for use with a smart device with a display screen. A neural network model trained with dataset images with embedded distance information can run in the background of the smart device. When receiving a captured image frame of the face of a child using the smart device, the neural network model can determine that the captured image frame is from a child, and further determine whether the face of the child is within a predetermined distance to the display screen based on a size of the face on the captured image frame. If the face is within the predetermined distance, the smart device can display an alert that the face of the child is too close to the display screen and pause one or more user applications until the child's face moves outside of the predetermined distance.