A saddle riding type vehicle including a main body extending along a longitudinal axis and having a front part, a tail part and a central part interposed between the front part and the tail part, at least one front wheel and at least one rear wheel, a motor operatively connected to at least one of the wheels, a system mounted on the main body for reducing a collision risk and comprising at least one active radar reflector, where the collision risk reduction system allows the radar visibility of the vehicle to be increased as a radar target, i.e. increasing its equivalent radar cross section, in order to reduce the risk of the vehicle being involved in a collision with another vehicle equipped with automotive radar which, in an operating condition and during operation, approaches the vehicle.

A system for testing vehicular radar is disclosed. The system includes a re-illumination element adapted to receive electromagnetic waves, and to transmit response signals. The re-illumination element includes: a plurality of miniature radar target simulators (MRTS's), each comprising: a receive antenna; a variable gain amplifier (VGA); an in-phase-quadrature (IQ) mixer; a variable attenuator; and a transmit antenna. The MRTS's are disposed in an array comprising rows and columns of the MRTS's, and each MRTS of the array is laterally spaced a distance p.sub.x and vertically spaced a distance p.sub.y from an adjacent MRTS. An incremental subtended azimuth angle (δϕ) and an incremental subtended elevation (δθ) angle are finer than an azimuth resolution specification (ϕ.sub.res) and an elevation resolution specification (θ.sub.res) of a radar device under test (DUT).

A distance measuring device according to an embodiment includes a first device including a first transceiver configured to transmit a first known signal and a second known signal and receive a third known signal corresponding to the first known signal and a fourth known signal corresponding to the second known signal, a second device including a second transceiver configured to transmit the third known signal and the fourth known signal and receive the first and second known signals and a calculating section configured to calculate a distance between the first device and the second device on a basis of phases of the first to fourth known signals, and the first transceiver and the second transceiver transmit/receive the first and third known signals one time each and transmit/receive the second and fourth known signals one time each, performing transmission/reception a total of four times.

The disclosed computer-implemented method may include transmitting, by at least one radar device, a frequency-modulated radar signal to at least one transponder located within a physical environment surrounding a user, detecting, by a processing device communicatively coupled to the at least one radar device a signal returned to the at least one radar device from the at least one transponder in response to the frequency-modulated radar signal, determining a beat frequency of the returned signal by performing a zero-crossing analysis of the returned signal in the time domain, and calculating, based at least in part on the beat frequency of the returned signal, a distance between the at least one transponder and the at least one radar device. Various other methods, systems, and computer-readable media are also disclosed.

A radio frequency identification (RFID) system includes an array of antennas to distinguish line-of-sight (LOS) paths from non-line-of-sight (NLOS) paths. The distance between adjacent antennas in the array of antennas is less than half the wavelength of the radio frequency (RF) signal of the system. Each antenna in the antenna array is also digitally controlled to change relative phase difference among the antennas, thereby allowing digital steering of the array of antennas across angles of arrival (AOAs) between 0 and π. The digital steering generates a plot of signal amplitudes as a function of AOAs. LOS paths are distinguished from NLOS paths based on the shapes (e.g., depth, gradient, etc.) of local extremes (e.g., maxima or minima) in the plot.

Disclosed active reflector apparatus and methods that inhibit self-induced oscillation. One illustrative apparatus embodiment includes an amplifier and an adjustable phase shifter. The amplifier amplifies a receive signal to generate a transmit signal, the transmit signal causing interference with the receive signal. The adjustable phase shifter modifies the phase of the transmit signal relative to that of the receive signal to inhibit oscillation. A controller may periodically test a range of settings for the adjustable phase shifter to identify undesirable phase shifts prone to self-induced oscillation, and may maintain the phase shift setting at a value that inhibits oscillation.

Disclosed active reflector apparatus and methods that inhibit self-induced oscillation. One illustrative apparatus embodiment includes an amplifier and an adjustable phase shifter. The amplifier amplifies a receive signal to generate a transmit signal, the transmit signal causing interference with the receive signal. The adjustable phase shifter modifies the phase of the transmit signal relative to that of the receive signal to inhibit oscillation. A controller may periodically test a range of settings for the adjustable phase shifter to identify undesirable phase shifts prone to self-induced oscillation, and may maintain the phase shift setting at a value that inhibits oscillation.

The disclosure provides some embodiments for securing long training field (LTF) sequence. A responding station (RSTA) configures a location management report (LMR) frame. The LMR frame is configured to include an LMR in respect of a previous measurement, and data to be used to generate a null data packet (NDP) for a current measurement that is to be performed following the previous measurement. The RSTA further encrypts the LMR frame using protected management frames (PMF) scheme, and transmits the encrypted LMR frame to an initiating station (ISTA) for generating an LTF sequence for the current measurement. In response to receiving an NDP announcement (NDPA) and an NDP for the current measurement from the ISTA, the RSTA generates an NDP for the current measurement based on the NDPA and the data using CCMP, and transmits the NDP to the ISTA.

A digital self-injection-locked (SIL) radar includes a digital SIL oscillator, a wireless signal transceiver and a digital frequency demodulator. The digital SIL oscillator generates a digital output signal. The wireless signal transceiver is electrically connected to the digital SIL oscillator to convert the digital output signal into a wireless signal for transmission to a target, receives a reflected signal from the target, and converts the reflected signal into a digital injection signal for injection into the digital SIL oscillator. Accordingly, the digital SIL oscillator operates in an SIL state and generates a digital oscillation signal. The digital frequency demodulator is electrically connected to the digital SIL oscillator to receive and demodulate the digital oscillation signal into a digital demodulation signal.

In a wireless local area network (WLAN) system, a transmitting STA may transmit wake-up time information related to a receiving STA to the receiving STA. The transmitting STA may transmit a sensing start frame to the receiving STA during a wake-up time. The transmitting STA may transmit a sensing frame to the receiving STA. The transmitting STA may transmit a feedback requesting frame for the sensing frame to the receiving STA. The transmitting STA may receive a feedback frame for the sensing frame from the receiving STA. The wake-up time information may include duration information for maintaining an awake state in which the receiving STA can monitor a signal received from the transmitting STA, and period information for transitioning to the awake state.