A communications system, including at least one tag and a plurality of beacons. The tags are configured to detect beacon advertisement messages, initiate a connection with at least one of the plurality of and transmit a Constant Tone (CT) to the at least one of the plurality of beacons. The tag is further configured to determine a location thereof based on the sampled CT from both the beacon and the tag and then report the location via the one of the beacons and/or an access point. Phase ranging mitigation techniques which include hop duplication, hop interpolation and ADC DC offset correction are employed so as to provide more accurate ranging values even in the case where there are many other devices in local proximity and which are competing for use of the same RF channels as those used by the tags and beacons.

The embodiments described herein provide ranging and location determination capabilities in RF-opaque environments, such as a jungle, that preclude the use of Global Positioning System (GPS) and/or laser ranging systems, utilizing transponders and Global Positioning System (GPS) receivers located on aerial vehicles. The aerial vehicles operate above the RF-opaque environment, and communicate with a ranging device within the RF-opaque environment on frequencies that propagate in the RF-opaque environment. The ranging device transmits RF signals to the transponders, which are received by the transponders and re-broadcasted back to the ranging device on a different frequency. The aerial vehicles also provide their coordinates to the ranging device using their GPS receivers. The ranging device uses information about the transmitted and received RF signals and the GPS coordinates of the aerial vehicles to calculate a perpendicular distance to a property line from the ranging device, and/or to calculate a coordinate location of the ranging device.

A data processing system for navigation using-spread spectrum signals herein implements causing a transceiver of the data processing system to transmit a first electromagnetic signal; receiving, via the transceiver, second electromagnetic signals associated with a first object responsive to the first electromagnetic signal, the second electromagnetic signals including first spread-spectrum signals and an identification of the first object incorporated into the first spread-spectrum signals, each respective second electromagnetic signal of the second electromagnetic signals being transmitted from a separate location on the first object; analyzing the second electromagnetic signals to obtain the identification of the first object; and determining a first estimated location of the data processing system relative to the first object by calculating a difference between the time of transmission of the first electromagnetic signal and a respective time of receipt of each of the second electromagnetic signals.

The present document provides a method by which first vehicle-to-X (V2X) user equipment (UE) for supporting distance measurement transmits a ranging response signal in a wireless communication system, the method comprising: receiving a ranging request signal from second V2X UE; and transmitting, to the second V2X UE, the ranging response signal as a response to the ranging request signal on the basis of distance measurement parameter information, wherein the distance measurement parameter information includes information on a cyclic prefix (CP) length used for the ranging response signal, and the CP length used for the ranging response signal is different from a CP length to be used in V2X data channel transmission.

The present document provides a method by which first vehicle-to-X (V2X) user equipment (UE) for supporting distance measurement transmits a ranging response signal in a wireless communication system, the method comprising: receiving a ranging request signal from second V2X UE; and transmitting, to the second V2X UE, the ranging response signal as a response to the ranging request signal on the basis of distance measurement parameter information, wherein the distance measurement parameter information includes information on a cyclic prefix (CP) length used for the ranging response signal, and the CP length used for the ranging response signal is different from a CP length to be used in V2X data channel transmission.

A distance measuring apparatus according to an embodiment includes, a filter section configured to perform band limitation on a transmission signal and output the transmission signal, and to perform band limitation on a reception signal from an antenna section and output the reception signal, a distance measuring section configured to perform a distance measurement computation based on the transmission signal and the reception signal, and to obtain a delay of a signal passing through the filter section and perform calibration of the distance measurement computation, a signal interruption section configured to interrupt transmission of a signal between the filter section and the antenna section, and a control section configured to control the signal interruption section to interrupt the transmission of the signal during a period of the calibration.

A transceiver circuit is disclosed. The transceiver circuit includes an antenna, a receiver RF chain configured to receive a receiver RF signal from the antenna, a transmitter RF chain configured to transmit a transmitter RF signal to the antenna, a frequency synthesizer configured to generate an oscillator signal, and a controller configured to cause the receiver RF chain to receive a first reflection signal from the antenna, down convert the first reflection signal to a non-zero intermediate frequency, and determine a range estimate to another transceiver circuit based on a phase of the first reflection signal.

A system and method for an efficient secure phase-based ranging using loopback calibration, including receiving, by a reflector during a current timeslot, an incoming constant tone (CT) signal having a phase shift; determining, by the reflector during the current timeslot or a previous timeslot, a phase shift correction value by using a receiver/transmitter (Rx/Tx) loopback path of the reflector; and/or generating, by the reflector, an outgoing CT signal having an updated phase shift by adjusting the phase shift of the incoming CT signal based on the phase shift correction value.

A system and method for an efficient secure phase-based ranging using loopback calibration, including receiving, by a reflector during a current timeslot, an incoming constant tone (CT) signal having a phase shift; determining, by the reflector during the current timeslot or a previous timeslot, a phase shift correction value by using a receiver/transmitter (Rx/Tx) loopback path of the reflector; and/or generating, by the reflector, an outgoing CT signal having an updated phase shift by adjusting the phase shift of the incoming CT signal based on the phase shift correction value.

A radio-frequency method for range finding includes modulating a reference signal having an intermediate frequency to a downlink signal having a carrier frequency using a clock signal. The downlink signal is transmitted to a tag using a transceiver. An uplink signal backscattered from the tag is received and demodulated using the clock signal. The uplink signal has a frequency that is a harmonic of the carrier frequency. A distance between the tag and the transceiver is calculated based on a phase of the demodulated uplink signal. A system for range finding includes a transceiver and a processor. The transceiver modulates a reference signal to a downlink signal and transmits the downlink signal. The transceiver receives and demodulates an uplink signal. The processor is configured to receive the demodulated uplink signal and calculate a distance between the tag and the transceiver using a phase of the demodulated uplink signal.