An electronic device includes a transceiver and a processor. The processor is operably connected to the transceiver. The processor is configured to transmit, via the transceiver, radar signals for activity recognition. The processor is also configured to identify a first set of features and a second set of features from received reflections of the radar signals, the first set of features indicating whether an activity is detected based on power of the received reflections. Based on the first set of features indicating that the activity is detected, the processor is configured to compare one or more of the second set of features to respective thresholds to determine whether a condition is satisfied. After a determination that the condition is satisfied, the processor is configured to perform an action based on a cropped portion of the second set of features.

Methods, apparatus, systems and articles of manufacture are disclosed to improve Doppler velocity estimation. An example apparatus is disclosed including a transmitter to transmit a first sweep signal at a first position in a first block of time during a transmit time sequence pattern, and transmit a second sweep signal at a second position in a second block of time during the transmit time sequence pattern, the second position different than the first position. The example apparatus also includes a velocity analyzer to determine a velocity and a direction of arrival of a target object identified during the transmit time sequence pattern.

A method and system improve on the accuracy of detecting the presence of people in a room. Aspects of the embodiments may be used for occupancy sensors by monitoring occupant physiological movements. In an embodiment, a Doppler radar sensor may be used to measure the occupant-related physiological signals, calculate the Riemann integral (RI) of the occupants' cardiopulmonary movement displacement, body movement index (BMI), and amplitude difference accumulation (ADA) of the body movement. A determination for detection of occupants may be by adaptive thresholding.

A non-invasive microwave measuring device (01) is for calculating the flow rate of a fluid. The device (01) includes a non-invasive microwave fluid velocity measuring device (03) having a patch antenna or horn antenna to generate a microwave signal (14) that is transmitted at a specific elevation angle α towards the fluid surface (16) and to receive the reflected microwave signal (15) from the fluid surface (16) with a doppler shift frequency. The measuring device (03) is suspended from a drone (02) by a suspension system (04). The suspension system (04) eliminates vibration noise generated by the drone (02). At least one vibration sensor eliminates false velocity readings. At least one angle sensor compensates for Pitch, Roll and Yaw from the drone (02) that influence the fluid surface velocity measurement.

The vehicle odometry and motion direction system and method is described. The vehicle odometry and motion direction system and method determines if the first ground speed data is acceptable. Ground speed data is calculated for all targets within a radar's field of view and targets ground speed data is processed to determine second ground speed data. The vehicle odometry and motion direction system and method determines trusted ground speed data using first ground speed data and second ground speed data and adjusts the trusted ground speed data due to errors in radar Doppler speed data.

A method and system are provided for generating a trigger signal from a radar signal received over the air from a radar under test. The method includes detecting power of the radar signal received from the radar under test at a radio frequency (RF) power detector, the radar signal including multiple bursts of RF energy in a burst pattern; identifying repeating radar frames from the burst pattern using the detected power of the radar signal, each radar frame having at least one burst; and creating trigger signals corresponding to the radar frames, respectively, by synchronizing to the at least one burst in each radar frame.

Embodiments are directed to a method for determining velocity of an object. The method includes in response to two interleaved chirp sequences being sent towards the object, processing responsive chirps of each of the two interleaved chirp sequences independently from one another to produce respective Doppler-spectrum data sets, and calculating the velocity of the object based on the respective Doppler-spectrum data sets. Each of the interleaved chirp sequences being characterized by a common time spacing between respective chirps of the respective chirp sequence, and each chirp of one of the chirp sequences being offset by an amount of time that is different than the common time spacing.

Implementations of the subject technology provide object detection and/or classification for electronic devices. Object detection and/or classification can be performed using a radar sensor of an electronic device. The electronic device may be a portable electronic device. In some examples, object classification using a radar sensor can be based on an identification of user motion using radar signals and/or based on extraction of surface features from the radar signals. In some examples, object classification using a radar sensor can be based on time-varying surface features extracted from the radar signals. Surface features that can be extracted from the radar signals include a radar cross-section (RCS), a micro-doppler signal, a range, and/or one or more angles associated with one or more surfaces of the object.

Systems and methods for modulation and demodulation using a micro-Doppler effect are described. In an embodiment, the method includes radiating, using a picosecond pulse generator with an antenna, a train of THz pulses that form a frequency comb, where the frequency comb is reflected from an object such that the frequency several tones in the frequency comb are shifted based on the speed of the object and demodulating the reflected frequency comb to recover a THz Doppler signature of the object.

A method for estimating a spin of a projectile, the method comprising obtaining a first data series representing a radial velocity of a projectile over time in accordance with a radar signal reflected from the projectile, subtracting a center velocity of the first data series from the first data series to form a second data series representing a variation of the radial velocity of the projectile around the center velocity over time, dividing the second data series into respective time intervals, estimating, for each of the time intervals of the second data series, a frequency of the variation of the radial velocity of the projectile around the center velocity, and determining a spin of the projectile based on the estimated frequencies of the variation of the radial velocity of the projectile.