In one implementation, first and second messages are received that include encoded position information for a transmitter. It is determined that both were received within some time of a previous message and that the second message was received within some time of the first message. A first location of the transmitter is determined based on the encoded position in the first message and the previously determined location. A second location of the transmitter is determined based on the encoded position in the second message and the previously determined location. It also is determined that the first and second locations are within a threshold distance. An updated second location of the transmitter is determined based on the encoded position information in the second message and the first location. A determination is made that the second location and the updated second location are within a threshold distance.

A measuring device (10) that is portable is configured to be capable of BLE communication with an information processing device (20). The measuring device (10) is configured to acquire living body related information of a user, receive a first advertising packet transmitted at a predetermined cycle from an information processing device (20), start encryption of the living body related information using a public key when the first advertising packet is received, calculate an estimated distance between the measuring device (10) and the information processing device (20) on the basis of a received signal strength indicator of the first advertising packet, and transmit a second advertising packet including the living body related information thus encrypted when the estimated distance is less than a first threshold.

A technique for measuring yaw (left-right direction) of a device includes obtaining a first measurement of an orientation of the device relative to a local magnetic frame of reference (FoR) and a second measurement of the orientation of the device relative to a spatial FoR, with both measurements made while the device is disposed at a known location and in the same orientation. The technique further includes computing an offset between the two measurements and storing the offset in connection with the known location. When the device later returns to the same location, the yaw direction of the device is determined based on acquiring a new measurement of the device's orientation relative to the local magnetic FoR and applying the offset as a correction.

A system and method for locating radio-frequency identification tags within a predetermined area. The method can incorporate sub-threshold superposition response mapping techniques, alone, or in combination with other methods for locating radio-frequency identification tags such as but not limited to time differential on arrival (TDOA), frequency domain phase difference on arrival (FD-PDOA), and radio signal strength indication (RSSI). The system can include a plurality of antennas dispersed in a predefined area; one or more radio-frequency identification tags; a radio-frequency transceiver in communication with said antennas; a phase modulator coupled to the radio-frequency transceiver; and a system controller in communication with said transceiver and said phase modulator. Calibration techniques can be employed to map constructive interference zones for improved accuracy.

A method of tracking wearable sensors attached to respective body parts of a user includes acquiring multiple yaw measurements from a wearable sensor by measurement circuitry within the wearable sensor, calculating errors in the yaw measurements based on comparisons of the yaw measurements with one or more yaw references, and correcting the yaw measurements by removing the errors.

A system, method, and computer program product are provided for estimating a distance to an object. The system includes a transmitter for transmitting RF signals from a location of an object. The system further includes measurement equipment, including a receiver, for receiving the transmitted RF signals as corresponding received RF signals and measuring a plurality of phase differences at different frequencies between the transmitted RF signals and the corresponding received RF signals. The system also includes a processor. The processor is configured to calculate normalized phases from the plurality of phase differences. The processor is further configured to calculate corrected phases by resolving one or more ambiguities from the normalized phases. The processor is also configured to obtain a characteristic curve using the corrected phases. The processor is additionally configured to provide an estimate of the distance based on the characteristic curve and the corrected phases.

Method of timing, in a receiver, a radio signal generated in and transmitted from a transmitter, the radio signal comprising a series of frequency chirps, the system including: receiving the radio signal from the transmitter; synthesizing projection vectors comprising a series of frequency chirps that are a complex-conjugate image of those comprised in the radio signal the projection vectors being time-shifted relative to one another by determined shift intervals of time; multiplying the received radio signal by the projection vectors and accumulating the results; interpolating the accumulating results to determine a peak time shift.

A system, method, and computer program product are provided for estimating a distance to an object. The system includes a transmitter for transmitting RF signals from a location of an object. The system further includes measurement equipment, including a receiver, for receiving the transmitted RF signals as corresponding received RF signals and measuring a plurality of phase differences at different frequencies between the transmitted RF signals and the corresponding received RF signals. The system also includes a processor. The processor is configured to calculate corrected phases by resolving one or more ambiguities from the plurality of phase differences. The processor is further configured to obtain a characteristic curve using the corrected phases. The processor is also configured to provide an estimate of the distance based on the characteristic curve and the corrected phases.

A system configured for rough localization of moveable cooperative targets. The system includes at least one laser tracker, having a moveable upper part connected to a base part, an optical target rough location detector automatically detecting a rough location of a cooperative target, a target fine position detector automatically detecting a fine position of a cooperative target within a fine position field of view, motors for changing an orientation of the moveable upper part, a motor controller, and a computer, a first and a second radio frequency telegram (RFT) transceiver (RFTT) anchor-module, wherein each RFTT anchor-module's position is referenced to the laser tracker, a cooperative target associated with a RFTT tag-module and each of the RFTT tag- and anchor-modules an evaluation unit configured for determining a RFT-transmission specific parameter based on the transmission of RFTs between the RFTT anchor- and tag-modules and providing said RFT-transmission specific parameter to the computer.

A system is provided for resolving ambiguity in a phase measurement used in a distance estimation for an object. The system includes a transmitter for transmitting RF signals from an object location. The system includes measurement equipment for receiving the transmitted RF signals as corresponding received RF signals and measuring a plurality of phases at different frequencies between the transmitted RF signals and the corresponding received RF signals. The system includes a processor. The processor is configured to calculate normalized phases from the plurality of measured phases. The processor is configured to perform an intra-frequency ambiguity resolution process that resolves an ambiguity for the normalized phases for a single frequency using an ambiguity factor. The processor is configured to perform an inter-frequency ambiguity resolution process that resolves an ambiguity for the normalized phases across multiple tones using a characteristic curve to provide a resolved phase measurement for the distance estimation.