A system for locating RFID tags in an area includes a platform and an RFID reader head associated with the platform. At least one support extends between the platform and an anchor position within an area. Separate support adjustment devices are associated with each support, with each support adjustment device being operable to adjust the length of the associated support between the platform and the anchor position associated with the support. So adjusting the length of the support varies the location of the RFID reader head in the area, thereby allowing an RFID reader associated with the RFID reader head to monitor a larger area than would otherwise be possible if the RFID reader were to remain in a fixed location. The RFID reader head itself may be movable with respect to the platform for finer adjustment of the position of the RFID reader.

This disclosure describes methods and apparatus to promote sustainable usage of smartphones such as preventing phone loss, preventing overheating and overcharging, and decreasing packaging waste. A method and apparatus to prevent phone loss is disclosed. Radio frequency beacons (or tags) attached to the owner transmit signals to the smartphone. The distance of the owner from the smartphone is estimated based on the quality of the received radio frequency signals in the smartphone. The system alerts user whenever the distance gets farther than a preset value. A method and apparatus to prevent overcharging of the battery is also disclosed. A plugging mechanism is presented that will be automatically detached from the smart phone when the battery is fully charged. Moreover, an alerting system is disclosed that alerts the user to stop using the device when the internal temperature of the device gets hotter than a preset threshold.

Systems and methods for locating one or more radio frequency identification (RFID) tags are provided. A phase difference of received information signals of illuminated RFID tags is utilized to locate the RFID tags. One or more exciters transmit interrogation signals to illuminate the RFID tags in which the exciters may have a plurality of antenna selectively configured to transmit through two or more antennas and to receive on one antenna. Multiple reads of the same RFID tag can also be performed to generate a probability model of the location of the RFID tag. An enhanced particle filter is applied to probability model to determine the exact location of the RFID.

Determining a location of a user device comprises a wireless computing system supported by an access point. The wireless computing system receives a signal from the user device. The system estimates a location of the user device based on RSSI and calculates a boundary around the estimated location. The wireless computing system selects a plurality of sections inside of the boundary and performs a coarse calculation of a location of the user device based on an angle of arrival of the received signal. The system determines sections of the plurality of sections that have results from the coarse calculation that are more likely to be a location of the user device. The system performs a fine calculation of the location based on the angle of arrival of the received signal within each of the sections. The system identifies a particular section as the location of the user device.

A system for estimating a location of a source transmitting a spectral-diversity signal having a known form but at least one unknown parameter is disclosed. The system comprises signal receiving circuits, each receiving the spectral-diversity signal and computing, for each signal carrier component in the spectral-diversity signal, a cross-ambiguity function based on the known form and on the received spectral-diversity signal. A central processor circuit estimates the location of the source, by calculating an extremum of an objective function constructed from all the cross-ambiguity functions.

Provided is a radio source position estimation system including a plurality of radio transmission devices spaced a predetermined distance apart from one another and configured to transmit radio frequency (RF) signals received from an arbitrary radio source and a central radio reception device configured to estimate a position of the radio source using the RF signals received from at least three radio transmission devices.

A software-defined radio system has a plurality of fixed radio receivers each operable to receive radio signals in a receiving band, to sample a received radio signal to produce a sample stream, and to send the sample stream over a network. The radio system includes at least one fixed sync signal transmitter operable to transmit predetermined sync signals in said receiving band to receivers of the aforementioned plurality. The radio system further comprises a data processing system which is connected to the network for receiving sample streams from the receivers. The data processing system is operable to align samples of a data signal contained in sample streams from different receivers by: detecting a sync signal in those sample streams; determining a timing offset between samples of the sync signal in those sample streams in dependence on predetermined locations of the different receivers and the transmitter of that sync signal; and aligning the samples of the data signal in dependence on the timing offset.

A software-defined radio system has a plurality of fixed radio receivers each operable to receive radio signals in a receiving band, to sample a received radio signal to produce a sample stream, and to send the sample stream over a network. The radio system includes at least one fixed sync signal transmitter operable to transmit predetermined sync signals in said receiving band to receivers of the aforementioned plurality. The radio system further comprises a data processing system which is connected to the network for receiving sample streams from the receivers. The data processing system is operable to align samples of a data signal contained in sample streams from different receivers by: detecting a sync signal in those sample streams; determining a timing offset between samples of the sync signal in those sample streams in dependence on predetermined locations of the different receivers and the transmitter of that sync signal; and aligning the samples of the data signal in dependence on the timing offset.

A system includes a first computing device having a first non-transitory machine-readable storage medium, first communication circuitry, and at least one first processor in communication with the first non-transitory machine-readable storage medium and the first communication circuitry. The at least one first processor is configured to execute instructions stored in the first non-transitory machine-readable storage medium to cause the first communication circuitry to receive a first signal from a first transmission medium, calculate a first authentication value for an object based on data included in the first signal, and cause the first communication circuitry to transmit a second signal to the first transmission medium. The second signal identifies whether the object is authentic based, at least in part, on the first authentication value.

A system includes a first computing device having a first non-transitory machine-readable storage medium, first communication circuitry, and at least one first processor in communication with the first non-transitory machine-readable storage medium and the first communication circuitry. The at least one first processor is configured to execute instructions stored in the first non-transitory machine-readable storage medium to cause the first communication circuitry to receive a first signal from a first transmission medium, calculate a first authentication value for an object based on data included in the first signal, and cause the first communication circuitry to transmit a second signal to the first transmission medium. The second signal identifies whether the object is authentic based, at least in part, on the first authentication value.