For passive sensor with resonator having a natural frequency, a method comprises: a first phase emission of an electromagnetic signal toward the passive sensor at an emission frequency, the resonator oscillating in a forced regime at the emission frequency and then oscillating at its natural frequency when the emission is cut off; a first phase reception of the damped signal oscillating at natural frequency emitted by passive sensor, a measurement of the frequency being performed; a second phase emission of an electromagnetic signal at the measured frequency toward the passive sensor, the resonator oscillating in a forced regime at the measured frequency and then oscillating at its natural frequency when the emission is cut off; a second phase reception of the damped signal oscillating at natural frequency, a measurement of the frequency being performed, determination of the natural frequency being stopped due to measurement performed in this second reception phase.

A transponder, able to equip a cooperative target facing a Doppler radar, includes at least one receiving antenna able to receive a signal transmitted by said radar and a transmitting antenna able to retransmit a signal. The signal received by the receiving antenna is amplitude-modulated before being retransmitted by the transmitting antenna to produce a variation of the radar cross-section of the target, the variation triggering a frequency shift between the signal transmitted and the signal received by the radar comparable to a Doppler echo. The transponder applies notably to the field of radars, more particularly for collaborative systems also operating at low velocity or nil velocity. It applies for example to assisted take-off, landing and deck-landing of drones, in particular rotary-wing drones, as well as manned helicopters.

A method for locating devices that transmit, backscatter or receive a wireless signal. The method comprising using each of one or more backscatter devices to modulate and backscatter a carrier signal transmitted by a transmitter. Modulating and backscattering the carrier signal generates a backscattered modulated signal comprising a sideband. The method further comprises receiving the one or more backscattered modulated signals with a receiver. At least one of the phase or amplitude of each sideband are used to determine at least one of: the distance between the transmitter and the backscatter device by which that sideband was generated, the distance between the receiver and the backscatter device by which that sideband was generated, and the sum thereof.

A system is disclosed for tracking receptacles serviced by a service vehicle. The system may have a locating device located onboard the at least one service vehicle and configured to generate a location signal indicative of a location of the at least one service vehicle, a receptacle sensor located onboard the at least one service vehicle and configured to generate an identity signal indicative of an identity of a receptacle in a vicinity of the at least one service vehicle, and a display. The system may also have at least one controller in communication with the locating device, the sensor, and the display. The at least one controller may be configured to show on the display an icon representing the receptacle overlaid on a map based on the location and identification signals.

Embodiments of the present invention include radio frequency identification location systems and methods. In one embodiment, RF signals are transmitted from one or more RFID readers, and in accordance therewith, backscattered signals are received from a tag to be located. A plurality of measured position parameters are used to determine a location of the tag. In one embodiment, one reader may transmit and three readers may receive signals to determine the position of a tag. In other embodiments, multiple readers may transmit and receive. In another embodiment, one reader may transmit from different positions to locate a tag. Embodiments of the invention may be used to track a moving tag. A reader's position may be determined using GPS, reference tags, or the reader may be positioned in a known location. A map may be provided to a user to display the location or movement of a tag or a corresponding item.

The invention relates to a localization apparatus for radio wave-assisted localization of a transponder, the localization apparatus comprising a control device, an evaluation device, a switching device, a first linear antenna array, and a second linear antenna array. The first antenna array and the second antenna array are controllable independently of one another, are arranged cross-wise with respect to one another, and include an angle not equal to zero between them. The control device is additionally adapted to control the switching device to connect the evaluation device alternately to the first antenna array and the second antenna array. The evaluation device is adapted to determine first and second reception angles at which a radio wave signal of the transponder is incident onto one of the first antenna array and the second antenna array when the first and second antenna arrays are connected to the evaluation device, respectively.

The present invention relates to systems, methods, and devices for consumers using RFID-tagged items for multichannel shopping using smartphones, tablets, and indoor navigation, preservation of consumer's privacy related to RFID-tagged items that they leave a retail store with, and automatically reading and locating retail inventory without directly using store labor. Robots and aerial mobile automated RFID reading devices are disclosed.

An identification or messaging system is provided that has embodiments including a embodiment with a structure with different faces and a base with reflective or resonance panels which are positioned at different receiving angles to detect direct signals and amplify them including in a sequence to be detected by an active emitter that emits electromagnetic radiation that is reflected and steered or resonated off or with the panels. An emitter can be an aerial platform with the emitter and a library of reflected or resonated signals that are associated with a particular sequence of panels on the structure which are associated with a particular entity identification or message. Thermal patterned and/or magnetic patterned panels (e.g., for backplane beamforming) and return signal steering can also be provided. Embodiments with secondary signaling systems can also be provided. A variety of various embodiments and methods are also provided.

An airborne redirection unit (ARU), for deflecting an RF energy beam, the ARU comprising: A canopy comprising a surface for slowing the rate of descent, A beam director supported at the canopy, the ARU being configured to focus the RF energy beam.

A tracking system comprising: a transmitter configured to steer an RF beam across a detection range, a passive RFID tag configured to be enabled for locating substantially when located in the center of the RF beam of the transmitter, and an RFID reader configured to detect the tag 104 once enable.