Abstract: Iterative geolocation of a stationary RF emitter through the use of TDOA may include the use of a single portable geolocation (e.g., TDOA) sensor, a pair of portable geolocation sensors and three of more portable geolocation sensors. Adding portable geolocation sensors to the iterative process reduces the constraints on the signals to be located as well as providing a reduction in the number of iterations required to obtain improved location accuracy.

Abstract: Embodiments provide systems and methods for determining the geolocation of an emitter on earth. A solution is obtained from two TDOA measurements that need not be acquired at the same time. A solution is obtained from a TDOA measurement and an FDOA measurement that need not be acquired at the same time and need not be coming from the same satellite pair. A location of an emitter can be determined from minimizing a cost function of the weighted combination of the six solutions derived from the two TDOA measurements and the two FDOA measurements, where the weight of each solution in the combination is determined based on the intersection angle of the two curves that define the possible locations of the emitter based on the TDOA and/or FDOA measurements.

Abstract: In a Wireless Location System (WLS) deployed in connection with a CDMA-based wireless communications system, Location Measurement Units are used to collect multi-path corrupted radio signaling for use in time difference of arrival (TDOA) and hybrid positioning methods. Signal processing techniques are used to enhance the WLS's ability to determine the minimally time-delayed multi-path component and thus increase the accuracy of the TDOA location in CDMA-based wireless communications systems. The signal processing includes a filtering technique for reducing the leading sidelobes of the cross-correlation function as well as a leading edge discovery procedure.

Abstract: Embodiments provide systems and methods for determining the geolocation of an emitter on earth based on weighted least-squares estimation based on two TDOA and two FDOA measurements, none of which need to be acquired at the same time. The four TDOA and FDOA measurements and the errors in each of the measurements are determined. Weights for the errors in the TDOA and FDOA measurements are determined, and the weights are applied in a weighted errors function. The weights account for the errors in the measurements and the errors in the satellite positions and velocities, and are dependent on the localization geometry. The weighted errors function is minimized to determine the location estimate of the unknown emitter.

Abstract: A method and apparatus for encoding information in a reference beacon signal for use in a time-difference-of-arrival/frequency-difference-of-arrival (TDOA/FDOA) geolocation system. Information is encoded in the reference beacon signal using variations in the times and frequencies of sequential reference signal transmissions. The encoded information may include an identifier associated with the transmitter of the reference beacon signal. A geolocation system receiving the reference beacon signal can thus differentiate it from non-cooperative target emissions as well as from other reference beacon signals.

Abstract: A method for measuring the time of arrival of radio signals within a network comprises receiving the received signals including at least a first pseudorandom code and a second pseudorandom code from at least one other node; identifying a frequency difference between the node and the other node using a phase difference between each of a maximum value of a cross-correlation provided by the first pseudorandom code and the second pseudorandom code; applying the frequency difference to the reception of the received signal; and calculating the time of arrival of the received signal comprising a time, measured with a local clock, when the cross-correlation has achieved the maximum value.

Abstract: A radio-based position location system for determining a relative position of a first object with respect to a second object may include a first radio operatively associated with the first object. A first directional antenna having at least a high gain region is mounted to the second object so that the high gain region is directed generally outwardly from the second object and defines a first detection zone. A second directional antenna having at least a high gain region is also mounted to the second object and is oriented so that the high gain region is also directed generally outwardly and defines a second detection zone. A second radio connected to the first and second directional antennas exchanges radio signals with at least the first radio to determine the relative position of the first object with respect to the second object at least in part by determining a time-of-flight of a radio signal.

Abstract: There is provided a method and system for positioning a transponder, the system comprising an antenna array of at least two spaced-apart antennas coupled to a common generating and switching unit. The generating and switching unit is configured for generating a periodic signal and switching the signal between said at least two antennas, constituting a positioning signal transmitted to the transponder. The system comprises a receiver for receiving a returned signal and a phase difference estimator coupled to the receiver and operable to measure phase differences between portions of the returned signal. The system further comprises a positioning utility coupled to said phase difference estimator and configured to determine the position of the transponder relative to the positioning system.

Abstract: A method and system for locating and positioning using broadcast frequency modulation (FM) signals, is provided. One implementation involves receiving FM stereo signals from three FM stations at one or more receivers, each stereo signal including a modulated 19 KHz FM pilot tone; and determining a geographical position at each receiver based on the phase difference of the demodulated pilot tones in the received FM signals.

Abstract: A method for the detection of an object by the TDOA principle is provided. The object transmits a signal, which is received by a plurality of stations having known positions. The stations' clocks can have different unknown time delays in relation to each other. An additional stationary reference station having a known position relative to the stations and transmitting a signal that is received by the stations is provided. An unknown transmission delay can be generated between the emission of the signal from the object and the emission of the signal from the reference station. For each station the difference in travel time between receipt of the signal from the object and the signal from the reference station and the difference of the travel time differences between the stations are determined. Mathematical algorithms for determining the location are performed.

Abstract: The present invention provides a method by which the position of a wireless emitter can be estimated by using a minimum of two wireless transceiver devices. The invention relies on physically moving the wireless transceiver devices to new position locations in order to obtain multiple time difference of arrival measurements. The time difference of arrival measurements can then be combined to derive estimates for the position of the emitter. At least one of the two wireless transceiver devices needs to be mobile with the other one fixed. Using this invention, any proportion of mobile and fixed transceiver devices can be used to derive the position of a wireless emitter. The wireless emitter to be located is not assumed to provide any information about itself to the wireless transceivers used for estimating its position location. The method is referred here as a Mobile-TDOA method or M-TDOA.

Abstract: A position measurement system is provided to determine a time difference between a first event and a second event. Position values are hereby determined from an individual periodic signal or from a plurality of periodic signals, wherein a first position value is determined using a measurement signal evaluation means when a first event occurs, and a second position value is determined using the measurement signal evaluation means when the second event occurs. The time difference is determined from the first and second position values. As a result, the time difference can be measured between two events with a high temporal resolution, with a reduction of electromagnetic interference caused by the time measurement.

Abstract: An autonomous ultrasonic indoor location system includes a location beacon transmitting apparatus and a location beacon receiving apparatus. The location beacon transmitting apparatus is configured to sequentially transmit US signals at a predetermined time interval upon transmission of a signal containing synchronization information.

Abstract: To provide a method of measuring a position of a node by using a radio communication system which comprises the node to send a position measuring signal, and a plurality of base stations to receive radio signals from the node, the method including: the base stations watching signals from the node through a predetermined channel; at least one of the base stations sending a reference signal after receiving of the position measuring signal; at least two of the base stations measuring the reception timing of the position measuring signal and the reception timing of the reference signal; and calculating the position of the node by using the reception timing of the position measuring signal and the reference signal measured by the base stations which have received the reference signal, and position information of the base station which has received the position measuring signal.

Abstract: A method and apparatus for estimating bias errors in a time-difference-of-arrival/frequency-difference-of-arrival (TDOA/FDOA) geolocation system using a reference signal transmitter in which position and/or motion information of the reference signal transmitter is encoded into the reference signal. The motion information may include the velocity and/or acceleration of the reference signal transmitter. The reference signal is received by multiple collection platforms operating in conjunction with a geolocation system and a reference correction processing system. The reference correction processing system receives, via the multiple collection platforms, the position and/or motion information, which is immediately and unambiguously associated with specific reference signal transmissions. The geolocation system estimates the position and/or velocity of the reference signal transmitter using conventional TDOA/FDOA techniques.

Abstract: Iterative geolocation of a stationary RF emitter through the use of TDOA may include the use of a single portable geolocation (e.g., TDOA) sensor, a pair of portable geolocation sensors and three of more portable geolocation sensors. Adding portable geolocation sensors to the iterative process reduces the constraints on the signals to be located as well as providing a reduction in the number of iterations required to obtain improved location accuracy.

Abstract: In a multilateration apparatus a correlator is provided with a time of arrival correlation window which is set to cater for the path lengths that may be experienced before a signal from an object to be located is received by receivers in the system. This may be on the basis of the largest possible path length in the system or on a receiver by receiver basis.

Abstract: A method of associating a universal time with time of arrival information of an identified component of a signal at a terminal of a radio positioning system is disclosed. In the method a marker signal with an associated universal time tag is obtained from a timing device (or the marker signal is obtained from an independent oscillator and a universal time tag assigned to the marker signal), and the time or phase relationship between the marker signal (or between the time of arrival information of said identified component respectively) and the oscillator is measured. The time of arrival information of said identified component relative to the oscillator is determined and the universal time corresponding to the time of arrival information of said identified component is calculated from said universal time tag and said measured time or phase relationship, before the calculated universal time is associated with said time of arrival information.

Abstract: This patent disclosure presents circuits, systems and methods to produce a stable signal from a reference signal source. These new inventions are far better than the current technologies to provide a stable signal with less phase noises. This new invention also provides a new approach to analyze the feedback control loop without using the traditional feedback control theory.

Abstract: A method for performing Time Difference Of Arrival (TDOA) that eliminates the need for a common time base or clock calibration and a system for implementing the method. The method relies on a packet transmitted from a reference wireless device (first wireless device) with a known propagation delay between the first wireless device and a second device, which serves as a common reference point for all TDOA estimates. When a packet is received from a wireless device by the first wireless device and the second wireless device, the time difference of arrival is computed based on when the signal was received by the first device and the second device, using the known propagation delay to compensate for differences in clocks and frequencies between the first wireless device and the second wireless device.

Abstract: Systems and methods for detection and geolocation of multiple emitters that are emitting RF signal energy on a common frequency, and that may be implemented to separate, geolocate, and/or determine the number of emitters (e.g., radio users) emitting on a common RF frequency. Real-time signal qualification processing may be employed to continuously monitor and collect incoming receiver tuner data for signal activity and ignore irrelevant noise data. Each set of data blocks from an emitter transmission signal may be defined as an emission cluster, and a set of time difference of arrival (TDOA)/frequency difference of arrival (FDOA) pairs may be computed for each emission cluster with each TDOA/FDOA pair yielding a geolocation result. A statistical qualification method may be used to produce a final geolocation answer from each set of emission cluster geolocation results, and a geolocation error ellipse computed for the final geolocation answer of each emission cluster.

Abstract: A multiple RF receiver and locating method using the same have developed. The multiple RF receiver includes: a clock generator for generating a clock according to multiple RF receiving modules included in a multiple RF receiving unit; a phase distributor for dividing the clock into clocks having different phases, and providing the clocks to the multiple RF receiving unit as clock sources; the multiple RF receiving unit for generating SFD (Start of Frame Delimiter) signals by using the phases of the clocks provided as the clock sources; and a time measuring unit for measuring the SFD signals for use as data for location measurement.

Abstract: A method estimates a delay in a time of arrival (TOA) of a transmitted signal by receiving the transmitted signal at multiple antennas via corresponding channels. Each received signal is correlated with the transmitted signal to obtain estimated channel coefficients and an estimated TOA. A variance of noise is also obtained for each received signal. A weight is determined for each received signal by dividing the channel coefficients by the variance of the noise. The weights are summed, and each weight is multiplied by the estimated TOA to produce a weighted estimated TOA, which are also summed. The summed weighted estimated TOA are divided by the summed weights to determine a final TOA estimate with respect to the transmitted signal.

Abstract: A method and an apparatus for estimating a location to support a location based service of a terminal in a mobile communication system are provided. The method includes receiving first reference signals from three base stations, calculating TDOAs, and solving a first equation using the TDOAs based on the first reference signals; when a solution of determining a location of a terminal based on the first equation is real or imaginary values, receiving second reference signals from the three base stations, calculating TDOAs, and solving a second equation using the TDOAs based on the second reference signals; and when a solution of determining the location of the terminal based on the second equation is real or imaginary values, determining the location of the terminal based on a relation between the first equation and the second equation.

Abstract: An apparatus comprises a first sensor mounted on a first platform for sampling a first portion of a continuous waveform occurring in a time window and for producing a first signal sample, a second sensor mounted on a second platform for sampling a second portion of the continuous waveform occurring in the time window for producing a second signal sample, and a processor for determining time difference of arrival measurements and for applying a maximum likelihood estimation process to combine multiple time difference of arrival measurements between multiple pairs of platforms, to estimate the location of an emitter of the continuous waveform. A method performed by the apparatus is also provided.

Abstract: Provided are a position tracking system and a position tracking method. The position tracking system includes at least one target node, a plurality of reference nodes having position information, and a position determination device. An arbitrary reference node among the reference nodes and the target node utilize a distance measurement message to measure a first time of arrival (TOA) and then transmit the first TOA to the position determination device. At least two other reference nodes adjacent to the arbitrary reference node and the target node listen to the distance measurement message to measure a second TOA and then transmit the second TOA to the position determination device, in order to track a position of the target node.

Abstract: The present invention is a method of finding propagation time and velocity of a transmitter. Specifically, receiving a signal at two or more receivers and using the scalar time relationship to determine propagation time and velocity of the transmitter for the purpose of location of the transmitter. This method is useful for both narrowband and broadband applications with increased accuracy over previous methods.

Abstract: A method and system for locating a wireless transmit/receive unit (WTRU) is disclosed. A wireless communication system comprises a plurality of access points (APs). Each AP broadcasts a message indicating class-of-service (COS) types that the wireless communication system supports. After a WTRU registers with one of the plurality of APs, the WTRU receives the broadcast message. The WTRU sets a timer for location update in accordance with an application that the WTRU is running and the COS type with which it is associated. The WTRU transmits a location update frame to the APs at the expiration of the timer, and a location of the WTRU is calculated using the location update frame.

Abstract: The present disclosure provides an RTD that is released from a single primary platform to collect signals from a target emitter and relay data back to a single primary platform, enabling the precise geo-location of the target emitter to be determined in a minimal amount of time. The RTD is released from a single platform and quickly creates a long signal collection baseline between the released RTD and the single platform. Various techniques for determining geo-location may be used with the present disclosure, such as angle of arrival (AOA), time difference of arrival (TDOA), and frequency difference of arrival (FDOA) methods.

Abstract: Positional information is provided at a place out of reach of radio wave. The process executed by a positional information providing apparatus includes the steps of: obtaining a received positioning signal (S610); specifying an emission source of the positioning signal (S612); obtaining, when the emission source of the positioning signal is outdoors, a navigation message included in the positioning signal (S622); executing a process for calculating the position based on the signal (S624); obtaining, when the emission source of the positioning signal is indoors, message data from the positioning signal (S630); obtaining coordinate values from the data (S632); and displaying positional information based on the coordinate values (S650).

Abstract: A method for performing Time Difference Of Arrival (TDOA) that eliminates the need for a common time base or clock calibration and a system for implementing the method. The method relies on a packet transmitted from a reference wireless device (first wireless device) with a known propagation delay between the first wireless device and a second device, which serves as a common reference point for all TDOA estimates. When a packet is received from a wireless device by the first wireless device and the second wireless device, the time difference of arrival is computed based on when the signal was received by the first device and the second device, using the known propagation delay to compensate for differences in clocks and frequencies between the first wireless device and the second wireless device.

Abstract: A receive device for determining a location of a transmitter device includes an evaluator formed to determine a first location of the transmitter device from a time of arrival of a first receive sequence, and a second location of the transmitter device from a time of arrival of a second receive sequence. In addition, the receive device includes a combiner formed to determine the location of the transmitter device from the first location and the second location.

Abstract: A location system comprising a plurality of base units for enabling the locating of a device by means of one or more location signals communicated between the device and the base units and signal processing equipment for: i. determining the location of the device in dependence on the manner in which the location signal(s) is/are received and ii. deriving calibration data for calibrating the system in dependence on the manner in which the location signal(s) is/are received.

Abstract: Systems and methods that may be implemented to determine the location of an emitter of electromagnetic radiation, such as an RF signal emitter having an unknown location, using at least two electromagnetic radiation sensor antennas that are co-located on a single sensing platform in combination with at least one other electromagnetic radiation sensor antenna located on another sensing platform.

Abstract: Techniques, systems and computer readable medium are disclosed for measuring a position of an object device. A position measuring apparatus includes a receiving unit designed to receive a signal transmitted from an object device for position measurement. The position measuring apparatus also includes a position computing unit designed to compute a position of the object device by applying Angle Of Arrival (AOA) and Time Of Arrival (TOA) techniques using the received signal. The position measuring apparatus also includes a medium channel estimating unit designed to estimate a channel of a medium, through which the received signal penetrates on a transmission path, using the received signal. The position measuring apparatus also includes a position correcting unit configured to compute a delay time caused by the received signal penetrating the medium using the estimated medium channel and correcting the position of the object device computed by the position computing unit using the delay time.

Abstract: An apparatus and method is disclosed for determining the position of a user interface mouse using time of arrival measurements. A transmitter transmits a signal to an array of receivers that are spatially separated from one another. The time difference of arrival for is found for each receiver relative to a predetermined reference receiver. Using the time difference of arrival (TDOA) of each receiver, the location in 3-dimensional space of each receiver, and the speed of sound the position of the transmitter in 3-dimensional space relative to the reference receiver may be found.

Abstract: In a multilateration system receivers are grouped into two groups. The first group is used to determine a position of a signal source, for example, an aircraft equipped with a SAR transponder. From the determined position, predicted time of arrival values are produced for the second group receivers. These are compared with the actual time of arrival values for the signals arriving at the second group receivers. A difference is determined and then the variation of that difference is determined as the aircraft travels in its track. The groupings are then varied and further variations determined. When the minimum variation is determined an alert is given that the second group has a receiver which is operating with a larger than desirable group time delay.

Abstract: A method for performing Time Difference Of Arrival (TDOA) that eliminates the need for a common time base or clock calibration and a system for implementing the method. The method relies on a packet transmitted from a reference wireless device (first wireless device) with a known propagation delay between the first wireless device and a second device, which serves as a common reference point for all TDOA estimates. When a packet is received from a wireless device by the first wireless device and the second wireless device, the time difference of arrival is computed based on when the signal was received by the first device and the second device, using the known propagation delay to compensate for differences in clocks and frequencies between the first wireless device and the second wireless device.

Abstract: A method for trilateration may include receiving a signal via each of a plurality of LOS paths and predicting performance of each LOS path. The method may also include filtering out signals received via LOS paths with performance below a predetermined threshold value. The method may further include performing trilateration using unfiltered signals to substantially determine a location of a device.

Abstract: Provided is an apparatus and method for computing the location of a radio beacon by using Time Difference Of Arrival (TDOA) and multiple frequencies. The apparatus and method of the present invention compute the location of a radio beacon without limitation in distance by using multiple frequencies and time difference of arrival to resolve the problem of phase ambiguity. A radio beacon location computing system includes a plurality of base stations configured to receive signals of multiple frequencies transmitted from the radio beacon, and detect and output phase differences and arrival time; and a location computing server configured to receive the phase differences and the arrival time outputted from the respective base stations, acquire calculation distances based on the phase differences, remove phase ambiguity from the calculation distances based on the arrival time, and compute the location of the radio beacon.

Abstract: A method for estimating the distance between a transmitter and at least one receiver. The transmitter has radio transmission circuitry, at least part of which is operable in a first operation mode for transmitting a first signal type within a first bandwidth and in a second operation mode for transmitting a second signal type including at least a ranging component which occupies a second bandwidth which encompasses and exceeds the first bandwidth. The method includes the steps of: (i) operating part of the radio transmission circuitry in a second operation mode, (ii) transmitting a signal of a second signal type, (iii) receiving a signal on one receiver and (iv) estimating the distance between the transmitter and a receiver from the ranging component in each received signal. A suitable transmitter and receiver for implementing the method are described.

Abstract: A system and method for estimating the range between two devices performs two or more ranging estimates with subsequent estimates performed using a clock that is offset in phase with respect to a prior estimate. The subsequent estimate allows estimate uncertainties due to a finite clock resolution to be reduced and can yield a range estimate with a higher degree of confidence. In one embodiment, these additional ranging estimates are performed at n/N (for n=1, . . . N?1, with N>1 and a positive integer) clock-period offset introduced in the device. The clock-period offset can be implemented using a number of approaches, and the effect of clock drift in the devices due to relative clock-frequency offset can also be determined. To eliminate the bias due to clock-frequency offset, a system and method to estimate the clock-frequency offset is also presented.

Abstract: The invention provides a reception time determining apparatus which can measure reception time to a high accuracy, without expanding an occupied bandwidth, and a distance measuring apparatus which uses the reception time determining apparatus.

Abstract: A system and method for estimating the range between two devices performs two or more ranging estimates with subsequent estimates performed using a clock that is offset in phase with respect to a prior estimate. The subsequent estimate allows estimate uncertainties due to a finite clock resolution to be reduced and can yield a range estimate with a higher degree of confidence. In one embodiment, these additional ranging estimates are performed at n/N (for n=1, . . . N?1, with N>1 and a positive integer) clock-period offset introduced in the device. The clock-period offset can be implemented using a number of approaches, and the effect of clock drift in the devices due to relative clock-frequency offset can also be determined. To eliminate the bias due to clock-frequency offset, a system and method to estimate the clock-frequency offset is also presented.

Abstract: Embodiments provide systems and methods for determining the geolocation of an emitter on earth. A solution is obtained from two TDOA measurements that need not be acquired at the same time. A solution is obtained from a TDOA measurement and an FDOA measurement that need not be acquired at the same time and need not be coming from the same satellite pair. A location of an emitter can be determined from minimizing a cost function of the weighted combination of the six solutions derived from the two TDOA measurements and the two FDOA measurements, where the weight of each solution in the combination is determined based on the intersection angle of the two curves that define the possible locations of the emitter based on the TDOA and/or FDOA measurements.

Abstract: Embodiments provide systems and methods for determining the geolocation of an emitter on earth based on weighted least-squares estimation based on two TDOA and two FDOA measurements, none of which need to be acquired at the same time. The four TDOA and FDOA measurements and the errors in each of the measurements are determined. Weights for the errors in the TDOA and FDOA measurements are determined, and the weights are applied in a weighted errors function. The weights account for the errors in the measurements and the errors in the satellite positions and velocities, and are dependent on the localization geometry. The weighted errors function is minimized to determine the location estimate of the unknown emitter.

Abstract: A novel beacon-based position location technique for efficient location discovery of untethered clients in packet networks is disclosed. The position location technique utilizes the time-difference-of-arrival (“TDOA”) of a first signal transmitted by a beacon of known location and a second signal transmitted by an untethered client. The TDOA of these two signals is measured locally by at least three non-collinear signal receivers. For each of the receivers, the TDOA is used to calculate a perceived distance to the client. A circle is then calculated for each receiver, centered on the receiver and having a radius equal to the perceived distance. At least two lines defined by points of intersection of the calculated circles are then calculated. The point of intersection of the lines represents the location of the client. To facilitate operation, the signal receivers may be arranged on vertices which define a convex polygon as viewed from above.

Abstract: The present invention relates to a navigation unit and base station used for determining location. A plurality of base stations are initialized to determine their location relative to each other. At the navigation unit, the time of arrival of at least one signal from each of the plurality of base stations is measured. From this, the location of the navigation unit relative to the plurality of base stations may be directly calculated using a closed solution. In one embodiment, a time of arrival technique is used and in another embodiment a time difference of arrival technique is used. Preferably an ultra-wide band frequency is utilized.

Abstract: Mobile LMUs can be used in a Wireless Location System to provide detection coverage in areas lacking adequate receiver coverage. The mobile LMUs can be used to detect the radio frequency (RF) transmissions from wireless handsets and devices over a period of time to permit determination of their location. The mobile LMU's time, position, and velocity is calculated and transmitted to a SMLC along with any transmissions received from wireless devices. The SMLC analyzes and resolves the Doppler component of the wireless device while compensating for the Doppler component of the mobile LMU. The position and velocity of the wireless device can be compared with real-time imagery taken by the mobile LMU platform to accurately determine the location of the wireless device. To enhance the mobile LMU's ability to detect a signal of interest, which may be very weak and/or corrupted by noise, a process may be employed whereby the low power mobile terminals' signals are received at receiving sites and stored in memory.

Abstract: Detecting a pulse of a signal includes receiving the signal and a light beam. The signal drives a spatial light modulator to modulate the light beam, where the complex amplitude of the modulated light beam is proportional to the signal current. The modulated light beam passes through an optical system and is detected by an optical detector array. A processor identifies a portion of the signal comprising the pulse.