Example embodiments relate to radar transceivers. One embodiment includes a radar transceiver. The radar transceiver includes a chirp generator for generating a chirp having an initial frequency and a final frequency. The radar transceiver also includes a controllable variable gain amplifier having an input connected to an output of the chirp generator. Further, the radar transceiver includes a control unit connected to a control input on the chirp generator and to a control input on the controllable variable gain amplifier. The control unit is adapted to output a first control signal to the chirp generator such that the chirp generator starts generating the chirp. The control unit is also adapted to output a second control signal to the controllable variable gain amplifier such that the controllable variable gain amplifier starts increasing an amplification in the controllable variable gain amplifier from a first amplification level to a second amplification level.

Techniques and apparatuses are described that enable full-duplex operation for radar sensing using a wireless communication chipset. A controller initializes or controls connections between one or more transceivers and antennas in the wireless communication chipset. This enables the wireless communication chipset to be used as a continuous-wave radar or a pulse-Doppler radar. By utilizing these techniques, the wireless communication chipset can be re-purposed or used for wireless communication or radar sensing.

Techniques and apparatuses are described that implement a smart-device-based radar system capable of performing near-range detection. The radar system employs a near-range detection module for detecting objects at near ranges in the presence of interference and a far-range detection module for detecting objects at far ranges. By evaluating separate range intervals, these modules can be designed to achieve a target false-alarm rate and detection performance by tailoring their processing to general characteristics of objects and interference at their respective range intervals. This enables the near-range detection module to detect a near-range object without generating a false detection associated with the interference. By utilizing the near-range detection module and the far-range detection module, the radar system can detect objects at both near and far ranges while achieving a target false-alarm rate.

Aspects of the present disclosure are directed to radar communications with disparate pulse repetition intervals, as may be implemented with radar transmission, receiver and processing circuitry. As may be utilized in accordance with one or more embodiments herein, time division multiplexing (TDM) multi-input multi-output (MIMO) radar signals are transmitted by transmitting sets of successive radar signals, each set having a pulse repetition interval (PRI) that is different than the PRI of sets of radar signals transmitted in another one of the sets. Positional characteristics of a target may be ascertained based on the PRI used in each of the sets and on phase characteristics of ones of the radar signals reflected from the target.

Systems and methods for calibrating a radar sensor based upon synthetic aperture radar (SAR) principles are described herein. A relative motion is induced between a radar sensor and a calibration target in the field-of-view of the radar sensor. The radar sensor receives returns from the calibration target. The radar sensor outputs, based upon the relative motion between the radar sensor and the calibration target, detections that are indicative of locations of points on the calibration target. A computing system generates calibration data based upon the detections, the calibration data comprising a correction factor between a position measured by the radar sensor and a corresponding true position of an object. The computing system programs the radar sensor based on the calibration data such that subsequent to being programmed, the radar sensor outputs detections based upon radar returns and the calibration data.

A radar system, comprising: a receive antenna configured to receive a receive signal reflected from a bullet, the receive signal exhibiting a Doppler shift according to the motion of the bullet; and a detector implementing a set of matched filters each configured to determine a measure of correlation between the Doppler shift of the receive signal and one of a set of pre-stored Doppler shifts, wherein each of the pre-stored Doppler shifts respectively represents the Doppler shift of a bullet passing the antenna at a different speed or a distance of a point of closest approach.

A method for determining a kinematic structure of a two-dimensional wind field and a system determining the same are provided. The method comprises receiving a plurality of Doppler velocities and a plurality of distances between a Doppler radar and a gate. Each Doppler velocity of the plurality of Doppler velocities corresponds to a respective distance of the plurality of distances between the Doppler radar and the gate. The method further comprises calculating a plurality of distance Doppler velocity values. The distance Doppler velocity values represent the plurality of measured Doppler velocities and the distance between the Doppler radar and the gate. The method further comprises estimating the kinematic structure of the 2D wind field using the plurality of distance Doppler wind velocity values.

The disclosed subject matter relates to Frequency Diversity Pulse Pair (FDPP) methods and technology implemented by, alternating the order of the pulse pair transmitted or order of the group of multiple pulses transmitted, the pulses differentiated based on the center frequency of each transmitted pulse. For example, where a pair of transmitted pulses have center frequencies f.sub.1 and f.sub.2, the pulses transmitted in pairs such that the first pair may be f.sub.1 followed by f.sub.2 and the second pair are a different order, such as f.sub.2 followed by f.sub.1.

A method for estimating a spin of a projectile, the method comprising obtaining from a radar transceiver a first time series comprising observations of a radial velocity of the projectile relative to the radar transceiver, calculating, from the first time series, a center velocity of the projectile, extracting from the first time series a second time series comprising a variation in the first time series around the calculated center velocity estimating a frequency of the second time series, and determining the spin of the projectile WO based on the estimated frequency of the second time series.

A sports ball is configured to enhance detection of spin properties by radar. The ball includes a spherical body having a first reflectivity with respect to radiation generated by a radar to be used in detecting spin of the ball. In addition, the ball includes a plurality of markers. Each of the markers has a second reflectivity with respect to the radiation generated by a radar to be used in detecting spin of the ball. The second reflectivity is different from the first reflectivity. The markers are distributed on the ball so that every great circle extending around an exterior surface of the ball is within a distance d of a projection on the exterior surface of the ball of at least one of the markers. The distance d is less than a radius of the ball.