Abstract: Time is transferred from an ultra wideband (UWB) transmitter to UWB receiver by transmitting a signal structure having an associated timing reference point together with a time value for the timing reference point. The UWB receiver receives the timing signal structure by synchronizing a receiver time base to the signal structure, demodulating the time value information, and using the demodulated time value information to set a receiver clock value. Propagation delay information is used to adjust the receiver clock value by advancing the receiver clock value to account for the propagation delay. In one embodiment, propagation delay is determined from a known distance between the transmitter and receiver. In another embodiment, the transmitter and receiver are part of a two-way link wherein propagation delay is measured by round trip timing measurements.

Abstract: A circuit of a node of a radio network, and a method for distance measurement with a transceiver for receiving a first signal with a first frequency by downmixing to an intermediate frequency, with a phase measurement unit, which is set up to determine a first value of a first phase for a first frequency value of the first frequency. The transceiver is formed to transmit a second signal with a first frequency value of a second frequency for determining a first value of a second phase. The control circuit is set up to change the first frequency and the second frequency, in that a second frequency value of the first frequency and the first frequency value of the first frequency have a frequency difference, and whereby a second frequency value of the second frequency and the first frequency value of the second frequency have the frequency difference. The phase measurement unit is set up to determine a second value of the first phase for the second frequency value of the first frequency.

Abstract: A radio frequency ranging system is grounded in establishing and maintaining phase and frequency coherency of signals received by a slave unit from a master unit and retransmitted to the master unit by the slave unit. For a preferred embodiment of the invention, coherency is established through the use of a delta-sigma phase-lock loop, and maintained through the use, on both master and slave units, of thermally-insulated reference oscillators, which are highly stable over the short periods of time during which communications occur. A phase relationship counter is employed to keep track of the fractional time frames of the phase-lock loop as a function of the reference oscillator, thereby providing absolute phase information for an incoming burst on any channel, thereby enabling the system to almost instantaneously establish or reestablish the phase relationship of the local oscillator so that it synchronized with the reference oscillator.

Abstract: A position determining system for a vehicle comprises an imaging unit for collecting image data. A wireless device reads or interrogates a radio frequency identification tag. An identification module determines whether the collected image data contains a visual landmark. A confirmation module determines whether the identified visual landmark is associated with a corresponding radio frequency identification tag having a particular tag identifier. A range finder or distance estimator determines a position offset of the vehicle with respect to the identified visual landmark. A data processor determines a vehicular position of the vehicle based on the determined position offset and a stored reference position associated with at least one of the visual landmark and the radio frequency identification tag.

Abstract: A device measures distance using a wireless signal that has two simultaneously transmitted components. Each of the two components includes a respective repeated code, the two codes having different durations. On receipt of the signal, the propagation distance is calculated separately for each code and compared. The calculated distance is considered to be valid only if the two calculations yield the same result. The durations of the two codes may be proportional to numbers having a relative prime relationship. The signal is generated and transmitted by the same device that performs the distance calculation, with the signal being retransmitted back to the device by a remote device, or may be generated and transmitted by the remote device.

Abstract: A device and a method for eliminating interference between a radar working on the L frequency band and an aeronautical radio navigation equipment item, such as DME (Distance Measurement Equipment). When the radio navigation equipment operates, the radar emits periodically in all or part of the frequency band and then halts its emissions, each emission has a given duration and being separated from the previous emission by an interval of silence.

Abstract: A ranging apparatus includes a reference pulse generator generating a reference pulse having a first frequency at a first point in time of transmitting a ranging signal from a first device; a delay pulse generator generating a delay pulse signal having a second frequency at a second point in time of receiving the a response signal transmitted from the second device in response to the ranging signal; an overlap detector detecting a third point in time that the reference and delay pulses overlap each other; a counter counting one of the reference and delay pulses until the third point; and a distance calculator calculating an amount of time from the first point to the second point by applying the first and second frequencies, and a count value of the counter and calculating the distance between the first device and the second device by using the amount of time.

Abstract: A system is disclosed for position registration and phase synchronization of monitors in a monitor network. Each monitor includes a transceiver having a transponder circuit with a calibrated transponder delay. To measure a distance between monitors, an oscillator at a first monitor generates a measurement signal which is transponded by a second monitor for receipt by the first monitor. A phase difference between the received signal and the first monitor oscillator is determined and used with the signal velocity and transponder delay to calculate the distance between monitors. The measured distances are combined with other data (e.g. monitor elevations) to calculate monitor locations. A phase delay is then measured by transmitting a signal from the first to the second monitor for comparison with the second monitor oscillator. A phase difference between oscillators (for use in synchronizing the monitors) is then calculated using the phase delay, separation distance and signal velocity.

Abstract: Improved distance estimation of a selected transmitter. An improved distance estimate from a target transmitter to a receiver is produced by assessing the target transmitter to determine transmit power, and combining this information with a propagation model, received signal strength, and reference signal strength indications. Target transmit power may be assessed through knowledge of the target device or device class, and/or transmit power reporting features of target wireless networks. The assessment may be made through looking up reported target device characteristics in a database, making inferences based on target device characteristics, or through standards-based diagnostic and/or reporting mechanisms.

Abstract: Provided are a method, apparatus, and medium for measuring a distance using a radio frequency (RF) signal. The method of measuring a distance includes setting the transmitter power of an RF signal of a signal generating module to a minimum so as to measure the longest distance when no obstacle exists, measuring a distance between the signal generating module and a fixed module using the RF signal whose transmitter power is set to the minimum, if the measured distance between the signal generating module and the fixed module is available, determining that no obstacle exists therebetween, and if the measured distance is not available, determining that an obstacle exists therebetween, and determining the distance according to the result of the determination of existence of an obstacle.

Abstract: A device measures distance using a wireless signal that has two simultaneously transmitted components. Each of the two components includes a respective repeated code, the two codes having different durations. On receipt of the signal, the propagation distance is calculated separately for each code and compared. The calculated distance is considered to be valid only if the two calculations yield the same result. Preferably, the durations of the two codes are proportional to numbers having a relative prime relationship. The signal is generated and transmitted by the same device that performs the distance calculation, with the signal being retransmitted back to the device by a remote device, or may be generated and transmitted by the remote device.

Abstract: A system for tracking an object in space for position, comprises a transponder device connectable to the object. The transponder device has one or several transponder aerial(s) and a transponder circuit connected to the transponder aerial for receiving an RF signal through the transponder aerial. The transponder device adds a known delay to the RF signal thereby producing an RF response for transmitting through the transponder aerial. A transmitter is connected to a first aerial for transmitting the RF signal through a first aerial. A receiver is connected to the first, a second and third aerials for receiving the RF response of the transponder device therethrough. A position calculator is associated to the transmitter and the receiver for calculating a position of the object as a function of the known delay and the time period between the emission of the RF signal and the reception of the RF response from the first, second and third aerials. A method is also provided.

Abstract: A system and method for highly selective intrusion detection using a sparse array of ultra wideband (UWB) radars. Two or more UWB radars are arranged in a sparse array around an area to be protected. Each UWB radar transmits ultra wideband pulses that illuminate the area to be protected. Signal return data is processed to determine, among other things, whether an alarm condition has been triggered. High resolution radar images are formed that give an accurate picture of the area to be protected. This image is used to detect motion in a highly selective manner and to track moving objects within the protected area. Motion can be distinguished based on criteria appropriate to the environment in which the intrusion detection system operates.

Abstract: A robot platform includes perceptors, locomotors, and a system controller. The system controller executes instructions for producing an occupancy grid map of an environment around the robot, scanning the environment to generate a current obstacle map relative to a current robot position, and converting the current obstacle map to a current occupancy grid map. The instructions also include processing each grid cell in the occupancy grid map. Within the processing of each grid cell, the instructions include comparing each grid cell in the occupancy grid map to a corresponding grid cell in the current occupancy grid map. For grid cells with a difference, the instructions include defining a change vector for each changed grid cell, wherein the change vector includes a direction from the robot to the changed grid cell and a range from the robot to the changed grid cell.

Abstract: A method and apparatus for measuring a distance in a wireless environment are provided, in which a first device transmits a distance measurement signal to a second device and receives at least one response signal for the distance measurement signal from the second device, matches the received response signal with a reference signal to detect an earliest response signal, and calculates a time taken from the transmission of the distance measurement signal to the second device and the reception of the response signal from the second device using a peak value of the matched reference signal.

Abstract: There is provided a device and method for detecting an overlap of pulse signals, capable of easily detecting a point where reference and delayed pulse signals overlap each other, and an apparatus for estimating a distance using the same. The device for detecting an overlap of pulse signals, the device detecting a point where first and second pulse signals having different frequencies begin to overlap each other, the device including: a duty adjustor generating a third pulse signal by increasing a duty of the second pulse signal; a pulse signal calculator multiplying the first and second pulse signals by the third pulse signal, respectively and adding respective results together to output a signal; and an overlap determiner determining a middle of a pulse with a greatest width in the signal outputted from the pulse signal calculator as a point where the first and second pulse signals overlap each other.

Abstract: The present invention provides for reducing power consumption of a positioning system having wireless beacons. A wireless transmitter static beacon is provided, which has a known position, signal strength, and range. A mobile device is positioned within the range of the static beacon and its position is determined based on a signal from the static beacon. Foreign wireless transmitter devices and their locations are detected. The immobility of the foreign devices is evaluated by periodically determining their positions and calculating the frequency with which their positions change, and by determining the devices' types. A subset of the foreign devices that are immobile are selected and amalgamated into the positioning system based on device type and position-changing frequency. The signal strength of the static beacon is reduced, which in turn reduces the range of the static beacon.

Abstract: A method of using a wireless communication system to determine locations is provided. The method including exchanging communication frames between at least two synchronized nodes in the communication system, wherein each communication frame includes at least one of data signals and radar signals. Determining distances of at least one of nodes and reflective sources based in least in part on at least one of direct and reflected radar signals and determining locations of at least one of the nodes and the reflective sources based on the determined distances.

Abstract: Disclosed is a distance measuring system comprising a transmitter that sequentially generates pulse sequences each having a plurality of pulse signals of equal amplitudes arranged at equi-time intervals, and transmits the generated pulse sequence as a radio wave; and a receiver that receives the pulse sequence transmitted from the transmitter as a radio wave, and has a distance calculator that acquires propagation times of the pulse signals in the received pulse sequence, and calculates a distance from the transmitter by giving different weightings to the pulse signals for the propagation times acquired for the respective pulse signals. As the amplitudes of the pulse signals in the received pulse sequence become larger, the weightings are made larger.

Abstract: A system and method for monitoring topological changes in a defined area. A grid of sensors is arranged in the area, with known distances between them. The sensors communicate wirelessly with a host computer, which individually addresses each sensor to instruct that sensor to be in an interrogate mode or responder mode. When a sensor is in interrogate mode, it measures distance from a neighboring sensor using radar (continuous wave phase difference) measurements. When a sensor is in responder mode, it receives, delays, and returns a signal received from a neighboring sensor.

Abstract: A system and method for monitoring topological changes in a defined area. A grid of sensors is arranged in the area, with known distances between them. The sensors communicate wirelessly with a host computer, which individually addresses each sensor to instruct that sensor to be in an interrogate mode or responder mode. When a sensor is in interrogate mode, it measures distance from a neighboring sensor using radar (continuous wave phase difference) measurements. When a sensor is in responder mode, it receives, delays, and returns a signal received from a neighboring sensor.

Abstract: The invention relates to a system, device, and method for using radar signals to measure the distance (h) to a surface from said device, the device comprising a transmitter and a transmitting antenna for transmitting radar signals, and a receiver and a receiving antenna for receiving a radar signal. The device may also comprise a first additional reflecting object separate from the receiving antenna, which additional reflector is designed so as to introduce a first predetermined alteration in radar signals upon reflection, with the device being equipped with means to differ between received signals with and without said predetermined alteration. The first predetermined alteration introduced by the first separate reflector can be, for example, a modulation shift or a shift in the polarization of the signal. In a typical embodiment the additional reflector is located close to the radar unit creating a double transition from radar unit to the surface.

Abstract: A communication device (e.g., an vehicle-mounted device) comprises a transmitter that transmits a distance-calculation signal with which to calculate a distance to a partner communication device (e.g., a mobile device), a detector that receives the distance-calculation signal returned from the partner communication device and detects a phase difference between the distance-calculation signal when transmitted and the distance-calculation signal when received, and a calculator that calculates the distance to the partner communication device based on the phase difference detected by the detector.

Abstract: A method reduces errors in two-way ranging between transceivers due to a frequency offset. A first transceiver measures a time CA1 between, transmitting a request frame and receiving a reply frame, and a time CA2 between receiving a first information bit of the reply frame and receiving a last information bit of the reply frame. A second transceiver measures a time CB2 between receiving the request frame and transmitting the last information bit of the reply frame, and a time CB1 between receiving a first information bit of the request frame and a last information bit of the request frame. A correction factor ? C = C B ? ? 1 C A ? ? 2 is applied according to C ^ B ? ? 2 = C B ? ? 2 ? o , and the one-way time is T ^ i = C A ? ? 1 - C ^ B ? ? 2 2 ? T i , where Ti is an idea period of the clocks of the transceivers.

Abstract: According to the invention, IEEE 802.15.4a packets are used for communications, ranging and passive radar (detecting changes/motions, tracking objects in the environment) functionality. Changes and motions in the environment are detected by exploiting the specific preamble structure of the IEEE 802.15.4a packets. A sequence of packets transmitted through an environment is received. Each packet includes a preamble. The preamble in each packet is despread to update a reference multipath profile and to obtain a current multipath profile for a currently received packet. The reference multipath profile is compared with the current multipath profile to detect an object in the environment.

Abstract: A system and method for highly selective intrusion detection using a sparse array of time modulated ultra wideband (TM-UWB) radars. Two or more TM-UWB radars are arranged in a sparse array around the perimeter of a building. Each TM-UWB radar transmits ultra wideband pulses that illuminate the building and the surrounding area. Signal return data is processed to determine, among other things, whether an alarm condition has been triggered. High resolution radar images are formed that give an accurate picture of the inside of the building and the surrounding area. This image is used to detect motion in a highly selective manner and to track moving objects within the building and the surrounding area. Motion can be distinguished based on criteria appropriate to the environment in which the intrusion detection system operates.

Abstract: An apparatus and method for low frequency asset tracking includes a low frequency transmitter tag associated with a cargo container or other high value commodity, a plurality of receivers that detect low frequency signals, and a microprocessor that uses algorithms and/or data pertaining to the propagation characteristics of the signal to locate the position of the container or high value commodity. The tag may include sensors to monitor container properties or conditions, such as temperature, motion, intrusion, RF fields, or other properties of interest. Sensor data may be modulated on the low frequency transmitter signal.

Abstract: A bistatic radar system having a transmitter that generates unique signals at spatially independent transmitter degrees of freedom and a receiver that filters the signal at each receiver degree of freedom into a group of signals identical in number to the number of transmitter degrees of freedom. The receiver formats the filtered signals into a 2-dimensional array of elements. The receiver rotates the array so that the new axes are aligned with the Doppler gradient. The data is then re-sampled and projected to linearize the clutter signal. The receiver may be integrated with a broad class of adaptive and non-adaptive clutter mitigation approaches such as electronic clutter tuning and projected bistatic space-time adaptive processing, or STAP.

Abstract: A system and method for highly selective intrusion detection using a sparse array of time modulated ultra wideband (TM-UWB) radars. Two or more TM-UWB radars are arranged in a sparse array around the perimeter of a building. Each TM-UWB radar transmits ultra wideband pulses that illuminate the building and the surrounding area. Signal return data is processed to determine, among other things, whether an alarm condition has been triggered. High resolution radar images are formed that give an accurate picture of the inside of the building and the surrounding area. This image is used to detect motion in a highly selective manner and to track moving objects within the building and the surrounding area. Motion can be distinguished based on criteria appropriate to the environment in which the intrusion detection system operates.

Abstract: A system for tracking an object in space for position, comprises a transponder device connectable to the object. The transponder device has one or several transponder aerial(s) and a transponder circuit connected to the transponder aerial for receiving an RF signal through the transponder aerial. The transponder device adds a known delay to the RF signal thereby producing an RF response for transmitting through the transponder aerial. A transmitter is connected to a first aerial for transmitting the RF signal through a first aerial. A receiver is connected to the first, a second and third aerials for receiving the RF response of the transponder device therethrough. A position calculator is associated to the transmitter and the receiver for calculating a position of the object as a function of the known delay and the time period between the emission of the RF signal and the reception of the RF response from the first, second and third aerials. A method is also provided.

Abstract: According to the invention, IEEE 802.15.4a packets are used for communications, ranging and passive radar (detecting changes/motions, tracking objects in the environment) functionality. Changes and motions in the environment are detected by exploiting the specific preamble structure of the IEEE 802.15.4a packets. A sequence of packets transmitted through an environment is received. Each packet includes a preamble. The preamble in each packet is despread to update a reference multipath profile and to obtain a current multipath profile for a currently received packet. The reference multipath profile is compared with the current multipath profile to detect an object in the environment.

Abstract: A system and method for electromagnetic position determination utilizing a calibration process. For calibration, a transmitter is positioned at multiple locations in an area of interest and multiple receivers receive and record signal characteristics from the transmitter to generate a calibration data set. The unknown position of a transmitter may be determined by receiving signals from the transmitter by multiple receivers. A locator data set is generated based on the comparison between two received signal characteristics determined for each receiver. The locator data set is compared with the calibration data set to determine the unknown position. In one embodiment, the signal comparisons are the differences between electric and magnetic field phase. Further embodiments utilize signal amplitude differences. A reciprocal method utilizing a single receiver and multiple transmitter locations is disclosed.

Abstract: A system and method for determining a position of a target within an acceptable tolerance using an iterative approach. A airborne or space-based measuring device is used to measure an estimated position of the target. The information from the measuring device is used in conjunction with either live captured or stored topography, or the like, information relating to the surface of the planet proximate the target to iteratively determine the actual position of the target.

Abstract: A system and method of dynamically updating an almanac of base stations with wireless phones that are controlled by end users. First, second, and third location information are received respectfully from a first, second, and third wireless phones. A position of each wireless device is known. The distance between each wireless device an uncooperative base station is determined while accounting for an uncertainty factor. A location of the uncooperative base station is calculated using the first, second, and third location information and the distances. The almanac is updated with the location.

Abstract: In a method for determining the distance between two transmitting and receiving stations, a transmission signal is generated in each station and is transmitted as a series of microwave pulses having a predefined pulse repetition frequency to the other respective station. The coincidence of pulses of the transmission signal sent by the respective station and the signal received by the station is detected in each station as a coincidence event, and the number of pulses transmitted and received by the respective station at the time of the coincidence event is determined. The distance between the stations is then calculated on the basis of the number of the determined pulses.

Abstract: A system and method for performing distance measurement using wireless signals. A time of flight calculation is enabled by an interrogating device that transmits an interrogation signal to a responding device, which returns a synchronized signal back to the interrogating device. The wireless signals between the interrogating device and the receiving device have a harmonic relationship. In one embodiment, a time shift of a received signal relative to a transmitted interrogation signal is determined based on a comparison of a first reference point on a signal representative of the transmitted interrogation signal and a second reference point on a signal representative of the received signal.

Abstract: A method for determining the distance between a base station (SLG) and a mobile object (DT1–DT3). A HF carrier frequency and an offset frequency (df) are predetermined for a QAM modulation. The HF carrier frequency is increased and decreased by the offset frequency in sequence over time in such a way that the HF carrier base frequencies (fo+df, fo?df) resulting in an HF carrier signal (TS) thus modulated exhibit an identical phase when the frequency is changed. The HF carrier signal is subsequently transmitted and simultaneously mixed (MIX) with an HF carrier signal (RS) that has been backscattered by the mobile object to obtain a carrier phase signal (PS). The corresponding carrier phase (PH1, PH2) for the two HF carrier base frequencies is determined in sequence over time. The difference (dPH) between these phases is used to calculate the distance between the base station and the respective mobile object.

Abstract: A vehicle positioning and tracking radar system includes a rotating antenna with a pair of spatially separated transmit feeds for simultaneously transmitting a pair of frequency-modulated continuous-wave (FMCW) electromagnetic signals having a first polarisation and a pair of spatially separated receive feeds for receiving an electromagnetic signal having a second polarisation, wherein the first and second polarisations are different from one another, such that the transmit feed and receive feed at the rotating antenna are isolated from each other; and a coded modulated transponder receives transmit signals from the rotating antenna with the first polarization and transmits a receive signal to the rotating antenna with the second polarization.

Abstract: A bistatic radar has a radar transmitter at a first location on a moving platform having a motion and a radar receiver at a second location, remote from the first location. The transmitter illuminates a target along an indirect path with an encoded radar signal. The target reflects the encoded radar signal to the radar receiver. The transmitter concurrently provides the encoded radar signal to the radar receiver along a direct path. The encoded radar signal is radiated at a start time from a central reference point, and contains the first location, the pulse start time, the central reference point and the motion of the moving platform. Bit synchronization codes are also included. The radar receiver receives the encoded radar signal from the radar transmitter along the direct path during a first time interval, and the same encoded radar signal reflected from the target along the indirect path during a second time interval.

Abstract: Frequency calibration of a bi-static type of radar system is performed by positioning radar transmitter and receiver in spaced relation to each other over a targeted seawater surface from which radar radiation along a forward radiation scattering path is reflected toward the receiver while radar energy is also radiated along a direct path to the receiver by-passing the seawater during sequential frequency measurement tests to determine a frequency diffraction factor. A radiation blocking barrier is positioned by a floating support at a reflection location at an angular position on the seawater surface for intersection by the forward scattering path to block reflection of radar energy radiation toward the receiver during one of the measurement tests.

Abstract: Separation determination systems for determining the separation between a base station and a transponder, whereby the base station includes an oscillating signal source, for generating a signal and a transmission device for broadcasting the signal. The transponder includes a receiving device, for receiving the signal from the base station, an oscillator, for generating a signal which is phase-coherent therewith and a transmission device for broadcasting the phase-coherent signal. The base station furthermore includes a receiver device, for receiving the phase-coherent signal from the transponder and a separation determination device for determining the distance between base station and transponder. The system and components may be improved whereby the oscillator in the transponder is energized with the received signal in order to generate a quasi-phase-coherent signal.

Abstract: A network, sensor and method are provided that utilize the capabilities of impulse radio technology to help monitor and/or control the environment within a building. In particular, the network includes a sensor attached to a first impulse radio unit that is capable of transmitting an impulse radio signal containing sensor related information to a second impulse radio unit. The second impulse radio unit is attached to a control station that uses the sensor related information (e.g., environmental related information, safety related information or surveillance related information) to monitor and/or control the environment within a building. In one aspect of the present invention, the control system can better control and monitor the environment within the building because the sensor may be moved around within the building and reference impulse radio units may interact with the first impulse radio unit to enable the determination of the current position of the sensor.

Abstract: A method for measuring distance and relative speed between two points, one of which is stationary. The method employs a radio signal modulating a periodic pulse train sent from stationary point to a movable point and simultaneously being retransmitted back to the stationary point with both the transmission and the retransmission occurring during exactly the same period of time. The number of pulses sent from the stationary point during that period of time is known. The number of pulses received by the stationary point during the transmission period, being less than all of the pulses sent to the movable point is used to determine the distance. The process is repeated after a precise time period of no transmissions and a new distance is between the points is determined. Knowing the change in distance and the precise time period over which the change occurred, permits a determination of relative speed of the two points.

Abstract: Surveillance systems and methods having both a radio frequency component and a video image are provided. The radio frequency component can determine the orientation and position of an RFID tag within a surveillance area. The orientation of the RFID tag is can be determined with respect to two or more orthogonal planes using inductance and a predetermined number of mutually orthogonal antenna loops.

Abstract: A method and apparatus is disclosed for determining the range between two planes, ownship (10) and target (12). Model data (66) estimating the velocity and position of target (12) is compared to actual flight path data of the target (12) passively received by ownship (10). The model data (66) and actual data is compared, and an error measurement is calculated. The model data is also subject to position and velocity constraints (78 and 82) which penalize unrealistic estimates. The error measurement and penalties are used to create a perturbation model (90) which is added to the model data to generate new model data. When the model data (66) conforms closely to the actual data, a range is computed from the model data (66).

Abstract: A system for measuring distance between a first locus and a second locus includes: (a) at least one beacon device; a respective beacon device of the at least one beacon device being situated at the first locus and transmitting a respective electromagnetic signal; and (b) at least one locator device; a respective locator device of the at least one locator device being situated at the second locus and receiving the respective electromagnetic signal. The respective locator device is situated at a distance from the respective beacon device within near-field range of the respective electromagnetic signal. The respective locator device distinguishes at least two characteristics of the respective electromagnetic signal. The respective locator device employs the at least two characteristics to effect the measuring.

Abstract: A system and a method for distance measurement utilizes a radio system. The distance is measured in coarse resolution, and in fine resolution that corresponds to distance attributes. The distance between first and second radio transceivers is determined from the coarse distance and the fine distance attributes.

Abstract: A method for determining the position of at least one second transmitting and receiving device (3) in respect of a first transmitting and receiving device in a passive access control system operating in the GHz range, comprising the steps of using a radar method, wherein signals (f1, f2) are received in the first transmitting and receiving device on the left-hand side and right-hand side of a modulation frequency (fmod), determining the distance of two signals (f1, f2) closest to the left-hand side and right-hand side modulation frequency (fmod) wherein the distance is proportional to the distance between the first transmitting and receiving device and at least one second transmitting and receiving device (3), so that multipath propagations are not taken into consideration.

Abstract: A transceiver for short-pulse radar applications is disclosed in which a shift register or the like is used to collect return signal information in a manner to reduce the number of transmit pulses needed and to increase the speed of determining the positions of multiple scattering objects. In addition, there is also disclosed cooperating transceivers arranged as transponders similarly utilizing shift registers or other pulse sampling techniques to accurately determine the linear distance between them based on relationships between or among propagation time, measured offsets, and internal clock skews. Corresponding methods are also disclosed.

Abstract: A network of localizers determines relative locations in three-dimensional space to within 1 cm by cooperatively measuring propagation times of pseudorandom sequences of electromagnetic impulses. Ranging transmissions may include encoded digital information to increase accuracy. The propagation time is determined from a correlator circuit which provides an analog pseudo-autocorrelation function sampled at discrete time bins. The correlator has a number of integrators, each integrator providing a signal proportional to the time integral of the product of the expected pulse sequence delayed by one of the discrete time bins, and the non-delayed received antenna signal. With the impulses organized as doublets the sampled correlator output can vary considerably in shape depending on where the autocorrelation function peak falls in relation to the nearest bin. Using pattern recognition the time of arrival of the received signal can be determined to within a time much smaller than the separation between bins.