Abstract: A system of cell phone positioning in real time is provided with specialized location device installations on multiplicity of base stations BSs in CDMA and TDMA cellular communication networks. The purpose of the positioning system is to enable tracking and locating large quantities of anonymous mobile cell phones MS in any number of network cells to be used for real time traffic-forecasting systems, emergency services E911, and other client-initiated position requests. Location data thus obtained can be continuously updated from vehicular-based cellular phones, collected, processed and used as a basis for input to intelligent transportation systems, such as real time urban traffic guidance for vehicular congestion and intelligent traffic control systems. The system is capable of covering large urban geographical areas and number of independent cell structures serving thousands of mobile cell phone clients.

Abstract: The time difference of arrival for a signal received at two or more receiving sites as transmitted from a wireless communications device, is determined by a frequency domain technique. The constituent frequencies of the signals received at the two or more receiving sites are determined, including the phase, or a value representative of the phase, of each frequency component. The phase values for the same frequency are subtracted to yield a phase difference values as a function of frequency. The slope of the function represents the time difference of arrival for the wireless communications device signal as received at the two receiving sites. To determine the mobile location based on the determined time difference of arrival values, a seed or initial location is first assumed for the wireless communications device and the distance difference of arrival (the time difference of arrival multiplied by the speed of light) is calculated.

Abstract: The surveillance system provides a means to augment Automatic Dependent Surveillance-Broadcast (ADS-B) with “look alike ADS-B” or “pseudo ADS-B” surveillance transmissions for aircraft which may not be ADS-B equipped. The system uses ground based surveillance to determine the position of aircraft not equipped with ADS-B, then broadcasts the identification/positional information over the ADS-B data link. ADS-B equipped aircraft broadcast their own position over the ADS-B data link. The system enables aircraft equipped with ADS-B and Cockpit Display of Traffic Information (CDTI) to obtain surveillance information on all aircraft whether or not the proximate aircraft are equipped with ADS-B.

Abstract: A radiation source location technique includes focusing a plurality of receivers (i.e., antennas) at the same location. At least one determined characteristic of the radiation received at each receiver provides information regarding the source of that radiation relative to each receiver. Determining a relationship between the determined characteristics allows for determining when the source of radiation is at the location where the receivers are focused. One example includes using high directivity, narrow beamwidth antennas and time based markers from a wireless digital communication signal for locating a mobile unit source of radiation.

Abstract: An RF object locating system and method that uses or includes a set of N (N>2) receivers (monitoring stations) located at fixed positions in and/or about a region to be monitored, one or more reference transmitters that transmit a timing reference, a location processor that determines object location based on time-of-arrival measurements, and at least one object having an untethered tag transmitter that transmits RF pulses, which may additionally include object ID or other information. Free-running counters in the monitoring stations, whose phase offsets are determined relative to a reference transmitter, are frequency-locked with a centralized reference clock. Time-of-arrival measurements made at the monitoring stations may be stored and held in a local memory until polled by the location processor.

Abstract: The position of a non-cooperating emitter is determined by detecting a signal from the emitter at three or more receiver communication devices positioned at different locations. The receiver communication devices determine respective detection times of the emitted signal in respective local time reference frames. To establish a common time reference frame for the emitted signal detections, each receiver communication device exchanges time synchronization signals with a reference communication device. Since any of the receiver communication devices and the reference communication device may be mobile, the signal exchange allows each receiver communication device to accurately determine the signal propagation time between itself and the reference communication device and factor the signal propagation time into an accurate adjustment of the local time reference frame.

Abstract: A system includes antenna control stations and a system interface. Each antenna control stations directs an orientation of an associated antenna to search for an identification signal associated with a mobile phone. The antenna control station communicates a detection response describing the orientation of the associated antenna. The system interface computes the location of the mobile phone based on the detection responses received from the antenna control stations.

Abstract: A process for measuring the location of people and objects carrying radio frequency (RF) transmitters (TXs) that transmit messages to a plurality of RF receivers (RXs) located in a space. Each RX is in communication with a computer of a computer network and forwards data received from the TXs to the network via its associated computer, along with a value indicating the signal strength of the received TX transmission. The signal strengths attributable to the same transmission are used to form a locating signal strength vector which is then compared to exemplary vectors generated from signal strength readings gathered in a calibration procedure from a set of representative locations in the space. In comparing the locating vector to the exemplary vectors, constraints are enforced on movements between locations (e.g., cannot pass through walls) and to probabilistically enforce expectations on transitions between locations.

Abstract: A method of inventory management is described. Upon activation of a button on a wireless device, the wireless device having a light source and a transceiver with a unique media address corresponding to a unique product, the device broadcasts a first signal including an order command and the unique media address by the transceiver via a wireless medium. A central controller then receives the first signal, identifies the unique media address included in the first signal, and using a database, identifies the unique product associated with the unique media address.

Abstract: According to one embodiment of the invention, a method for locating a source of a signal includes detecting, at a plurality of locations, a near-field signal. The method also includes processing the near-field signal. The method further includes locating a source for the near-field signal based on the processed near-field signal detected at a plurality of locations.

Abstract: A radiation source location technique includes focusing a plurality of receivers (i.e., antennas) at the same location. At least one determined characteristic of the radiation received at each receiver provides information regarding the source of that radiation relative to each receiver. Determining a relationship between the determined characteristics allows for determining when the source of radiation is at the location where the receivers are focused. One example includes using high directivity, narrow beamwidth antennas and time based markers from a wireless digital communication signal for locating a mobile unit source of radiation.

Abstract: Described herein is a system and method for detecting the position of a remote emitter (1) where the emitter (1) is emitting a radio frequency signal (2) in a radio field (3). The system and method uses at least one receiver (4) which is moveable within the environment of the radio field (3), each receiver (4) measuring and recording the amplitude of the radio frequency signal (2) and recording its precise location using a GNSS or GPS receiver. The data recorded is processed and compared to data predicted by the receiver (s) (4) to estimate a location of remote emitter (1).

Abstract: An intrusion detection system and method are provided that can utilize impulse radio technology to detect when an intruder has entered a protection zone. In addition, the intrusion detection system and method can utilize impulse radio technology to determine a location of the intruder within the protection zone and also track the movement of the intruder within the protection zone. Moreover, the intrusion detection system and method can utilize impulse radio technology to create a specially shaped protection zone before trying to detect when and where the intruder has penetrated and moved within the protection zone.

Abstract: Emitter target range and heading are estimated from bearing measurements enhancing bearings-only estimator convergence to a target track, and permitting optimization of an observer position relative to the target at the end of the total bearing measurement period. One or more estimates of the target range, speed and heading made from bearing measurements before an observer maneuver are used to determine the most appropriate observer maneuver giving complete bearings-only target-motion-analysis observability. A set of parameters characterizing a set of potential emitter signal sources is generated based on measured emitter characteristics. A most probable set of emitter platforms is identified and the emitter operating mode and corresponding platform set are associated with a kinematic regime set. A specific speed or discrete set of speeds best adapted to a set of all possible platform missions, emitter speed as a continuous function of emitter range, and emitter range are all determined.

Abstract: A direct multilateration target tracking system is provided with the TOA time stamp as an input. A technique of tracking targets with varying receiver combinations is provided. Methods of correlating and combining Mode A, Mode C, and Mode S messages to enhance target tracking in a passive surveillance system are provided. A direct multilateration target tracking system is provided by TOA tracking and smoothing. A technique for selecting best receiver combination and/or solution of multilateration equations from a multitude of combinations and/or solutions is provided. A technique for correcting pseudorange values with atmospheric conditions is provided. A technique for improving height determination for regions of poor VDOP in a 3D multilateration system is provided.

Abstract: A radio frequency (RF) motion capture system includes stationary sensor receivers, one or more transmitter marker tags on one or more objects to be tracked within a capture zone, at least one stationary reference tag transmitter, and a processing system for processing the received signals. The individual tags transmit burst of spread-spectrum RF signals. The transmitted signals include a common sync code, and a tag identification code that is unique to each tag. By computing double differences of pseudoranges, clock terms are cancelled out allowing the processing system to precisely determine the location of each tag as it moves through the capture zone without the need to synchronize clocks between sensors and tags. The system can be used for RF match moving.

Abstract: A lightning detection and data acquisition system. A plurality of remote programmable sensor is utilized to detect cloud to ground and IC lightning strikes. Analog representations of the lightning strikes are converted to digital signals. The digital signals are classified according to user changeable criteria. The classified digital signals are compressed and optionally decimated. The compressed information is transmitted to a central location where it is decompressed and used to correlate the location, magnitude, and travel path of the detected lightning strikes.

Abstract: The present invention is useful in connection with calibration of a wireless location system based on RF signals within a facility. Identification devices are provided at fixed locations which are selected within the facility. The RF environment is sampled at selected locations and data representing the sampled RF environment and the corresponding selected location is provided to a computer which maintains a database corrolating the RF environment data and the selected locations to be used with calibrating a location system.

Abstract: A threshold tracking loop (TTL) (400) for detecting the time of arrival of a spread spectrum wireless communication signal includes a pseudo-noise (PN) generator (440) for generating a receive PN code for use in spread spectrum decoding and a series of time delay units (401-408) for adjusting a phase offset of the PN code. A first PN despreader (423) is coupled to the time delay units and PN generator for despreading an early pilot signal (413). A second despreader (425) is coupled to the time delay units and PN generator for despreading a late pilot signal (415). A first comparison circuit (443) is coupled to the first PN despreader for comparing a signal value of the early pilot signal with a preselected threshold value (322) and for advancing the PN code phase offset if the early signal value is greater than the threshold value.

Abstract: A system includes antenna control stations and a system interface. Each antenna control stations directs an orientation of an associated antenna to search for an identification signal associated with a mobile phone. The antenna control station communicates a detection response describing the orientation of the associated antenna. The system interface computes the location of the mobile phone based on the detection responses received from the antenna control stations.

Abstract: A positioning system and method provide fast and accurate position of a portable signal transmitter. It is particularly suitable for tracking applications in a local area, e.g., virtual environment. This system includes at least two relay stations, at least one portable signal transmitter, and one central station. The portable signal transmitter emits a tracking signal, which is received by each of the relay stations and then relayed to the central station wirelessly or by a wired connection. Time data are measured either in the central station or in each of the relay stations. A data processor calculates the position coordinates of the portable signal transmitter. The position system can be used to track the location of one object within another object, such as a medical device within a human body.

Abstract: A method and apparatus for determining and correcting for phased array mispointing errors, particularly those due to structural deformation, is disclosed. The method comprises the steps of receiving a signal from each of a plurality of signal sources at at least one receiving sensor disposed away from the phased array in a direction at least partially toward a receiver of a transmitted signal from the phased array, and determining the phased array pointing from the received signals. The apparatus comprises a receiving sensor for receiving a signal from each of a plurality of signal sources, the receiving sensor disposed away from the phased array in a direction at least partially toward a receiver of a transmitted signal from the phased array, and an array pointing computer for determining the direction of the phased array from the received signals.

Abstract: A method and system for positioning mobile units using angle measurements taken by neighboring mobile units is disclosed. A selected mobile unit and mobile units in the vicinity of the selected mobile unit are selectively instructed to measure and report information related to the position of the selected mobile unit. The reported information is used to compute a position of the selected mobile unit.

Abstract: The invention refers to a ranging system for determining ranging information of a spacecraft carrying a component of a communication channel. In order to provide a ranging system for determining ranging information of a satellite carrying a transponder as well as to provide a method thereof which yield a sufficient accuracy without causing further costs when narrow spot beams by the transponder are used, a ranging system according to the invention comprises a plurality of receiving stations at different locations on earth, wherein each receiving station is arranged for receiving a reference signal from said component; synchronisation means for providing a synchronised time base between the plurality of receiving stations; calculation means for calculating said ranging information in accordance with the propagation time of each received reference signal and with the synchronised time base; wherein at least one receiving station comprises a correlation receiver for receiving the reference signal.

Abstract: A source localising method comprises the steps of measuring the power received by a set of sensors and selecting N measurements from respective sensors, where N is an even number and at least four. N−1 different direct power ratios are constructed each derived from the N power measurements, with different numerators and denominators derived from respective halves of the measurements in each case. The construction of N−1 direct power ratios is facilitated by the use of a suitably constructed Hadamard matrix. Each direct power ratio may be converted with a logarithmic transformation into a linear combination of measured powers.

Abstract: An RF object locating system and method that uses or includes a set of N (N>2) receivers (monitoring stations) located at fixed positions in and/or about a region to be monitored, one or more reference transmitters that transmit a timing reference, a location processor that determines object location based on time-of-arrival measurements, and at least one object having an untethered tag transmitter that transmits RF pulses, which may additionally include object ID or other information. Free-running counters in the monitoring stations, whose phase offsets are determined relative to a reference transmitter, are frequency-locked with a centralized reference clock. Time-of-arrival measurements made at the monitoring stations may be stored and held in a local memory until polled by the location processor.

Abstract: Two or more receivers of known location receive RF bursts from a wireless moving object containing a transmitter that transmits periodic RF bursts. The receivers are gated with precision swept timing that repeats at the exact transmit RF burst period to produce precision expanded time representations of the received RF bursts. The expanded time representations correspond to RF burst arrival times from the transmitter, which are used to calculate the location of the transmitter. A writing pen application includes an RF transmitter in a writing pen and four RF receivers beneath the surface of a writing tablet where RF propagation from the pen to the receivers cannot be blocked by a user's hand. Two RF transmitters, one located at each end of the pen, may be employed to measure pen tilt and for 3-D tracking. Spatial resolution is more than 600 dpi at 100 location fixes per second.

Abstract: A process for measuring the location of people and objects carrying radio frequency (RF) transmitters (TXs) that transmit messages to a plurality of RF receivers (RXs) located in a space. Each RX is in communication with a computer of a computer network and forwards data received from the TXs to the network via its associated computer, along with a value indicating the signal strength of the received TX transmission. The signal strengths attributable to the same transmission are used to form a locating signal strength vector which is then compared to exemplary vectors generated from signal strength readings gathered in a calibration procedure from a set of representative locations in the space. In comparing the locating vector to the exemplary vectors, constraints are enforced on movements between locations (e.g., cannot pass through walls) and to probabilistically enforce expectations on transitions between locations.

Abstract: A method for determining a location of an emitter in a monitored area includes the step of providing an array representative of the monitored area, the array including a plurality of elements. Next, at least one first curve and at least one second curve is provided in the array. The first and second curves are representative of possible locations of the emitter in the monitored area. Then, possible emitter locations are identified at intersections of the first and second curves. The intersections are identified by determining locations in the array where an element having an assigned attribute corresponding to a first curve has a predetermined number of adjacent elements having an assigned attribute corresponding to a second curve.

Abstract: Disclosed is a method and apparatus for locating a wireless device especially useful for locating a cellular telephone making a call from an unknown location. The call may be a request for emergency assistance, or for location-based commercial services, for example. Various embodiments may optionally include a mobile location component, a cellular telephone enabled to chirp-on-demand, and/or an interferometer link. A mobile location component may include a directional antenna. The directional antenna may be mounted on an antenna boom on top of an emergency vehicle, for example. The mobile location component may alternately or additionally comprise a hand-held unit. System elements may cooperate to generate a situation awareness map or other display. The mobile location component may be moved in the general direction of a first location calculation associated with a first circular error of probability.

Abstract: A system and method for detecting a target object through foliage includes a transmitter for generating a low-frequency electromagnetic signal. The signal is directed toward a potential target object for reflection from the potential target object. The system further includes a plurality of mutually dispersed sensors for receiving the reflected signal from the target object. A mechanism is provided to determine the relative locations of the sensors. Signal information from the received signals is sent to a central processor. The central processor inputs the signal information into a beamformer algorithm such as the Maximum Likelihood Method (MLM) to reduce sidelobe ambiguities and resolve the true location of the target from the signal information.

Abstract: A system and process for determining the location of persons and objects using transmitters (TXs) that transmit location messages to at least one receiver connected to a computer, in a network of computers. The TXs are small, battery-powered, radio frequency transmitters carried by the person or object whose location is being tracked. The location message signals are picked up by one or more receivers (RXs) scattered throughout an environment. Each TX transmits a code with a unique identifier, and each RX also has a unique identifier. The RXs measure the signal strength of each location message transmission. Each RX is connected to a computer, which is in turn connected to a network. The RX computers send the data messages including the TX identifier, radio signal strength, and RX identifier to a central computer via the network. The central computer uses this information to determine the location of the TXs.

Abstract: The phase difference between a known stable reference signal (11) and a known signal output by a wireless mobile communication device (5, 5B) is determined at several known locations (1-4, 1B-4B). The location of the wireless mobile communication device is then determined from the phase difference information. Also, the approximate location of a wireless mobile communication device (5A) can be estimated by transmitting a message from the device at a predetermined power level (71), and determining where among a plurality of predetermined locations (1A-4A) the transmitted message has been received.

Abstract: An Automatic Location Identification (ALI) system for cellular telephone networks, along with a pseudo Automatic Number Identification (ANI) typically representing a particular face of a cell tower receiving an emergency call, compares the electromagnetic footprint of the call to stored field strength data to ascertain the coordinates of a small polygon subsuming the location of the caller. Along with connecting the emergency call to the emergency (i.e., “911”) dispatch center, the system also transmits the caller's Directory Number (DN), the cell tower location, and the coordinates of the location polygon. This approach gives the emergency dispatch center a more definite location than prior art approaches which only provide a large triangular area based on a cell tower face as the location region of the caller. It can also serve as a back-up to more sophisticated resource-intensive approaches using signal time differentials and the like.

Abstract: A system is provided for detecting the presence of two or more acoustic sources or targets such as vehicles that are traveling between an array of unattended passive ground sensors, in which the sensors each include a phased-array microphone and processing to determine the bearing to the acoustic target. The bearings from pairs of these sensors are subtracted one from the other to provide a bearing line difference “delta” which is the indicator of the presence of an acoustic target close to the line between the two sensors of the pair. A tripwire threshold indicating the presence of a target is set when the absolute value of this bearing line difference “delta” is greater than, for instance, 150°, with the “delta” being 180° when the target is on the line between the two sensors.

Abstract: A method and system for positioning mobile units using angle measurements taken by neighboring mobile units is disclosed. A selected mobile unit and mobile units in the vicinity of the selected mobile unit are selectively instructed to measure and report information related to the position of the selected mobile unit. The reported information is used to compute a position of the selected mobile unit.

Abstract: A method for tracking objects within a three-dimensional capture zone includes placing at least four sensors around the capture zone. A stationery reference tag is placed within the capture zone. Tags are coupled to objects to be tracked in the capture zone. Signals are periodically transmitted from the reference and object tags. These signals are received and the identification code, and code phase and carrier phase measurements are extracted. The code phrase and carrier phase measurements are processed to determine the position of each object tag with respect to the reference tag at each sampling instant.

Abstract: The present invention is a method of determining the time of arrival of an incident signal transmitted utilizing a code word that is interspersed with noise and diffracted and reflected signals of the incident signal. The incident, diffracted and reflected signals and noise are collectively defined as a combined signal. The method comprises receiving the combined signal; obtaining the code word to apply to the combined signal; comparing the combined signal with the code word to filter the incident signal and diffracted and reflected signals arising from the incident signal from the combined signal; utilizing the incident signal and related diffracted and reflected signals to determine a first parameter indicative of the incident signal's time of arrival; and filtering the first parameter utilizing a multipath mitigation algorithm to mitigate the influence of the diffracted and reflected signals to obtain a second parameter indicative of the incident signal's time of arrival.

Abstract: A system and method for estimating the position of an object within a volume. The system uses the time difference of arrival of signals at a plurality of receivers to establish the position of an object, using only the substantially multipath free portion of the received signal for analysis purposes. A prior model of the object and/or volume is used to assist the location determination process.

Abstract: A system and method of the present invention determines the location of a transmitting mobile unit. A mobile unit has a global positioning system (GPS) unit and transmitter for transmitting an RF signal that includes an identification of the mobile unit and GPS location coordinates, if available. At least one receiver forms a first infrastructure and is contained within an area having good GPS reception for receiving a transmitted signal from the mobile unit when in the area relating to the identification of the mobile unit and the GPS location coordinates or other GPS data obtained from the GPS unit. At least one receiver forms a second infrastructure and is contained within an area having poor GPS reception for receiving transmitted signals from the mobile unit when in the area relating to an identification of the mobile unit and for measuring the angle of arrival and/or time of arrival, multipath profile, or other characteristics of transmitted signals from the mobile unit.

Abstract: A system and method for performing real-time position detection and motion tracking of mobile communications devices moving about in a defined space comprised of a plurality of locales is provided. A plurality of access points are disposed about the space to provide an interface between mobile devices and a network having functionality and data available or accessible therefrom. Knowledge of adjacency of locales may be used to better determine the location of the mobile device as it transitions between locales and feedback may be provided to monitor the status and configuration of the access points.

Abstract: The determination of the geographical location of a signal emitter by the coherent, time integrated measurement of received signal wavefront phase differences through a synthetic aperture and the reconstruction of the wavefront of the received signal. The location of an emitter is determined by coherently measuring the phase gradient of an emitted signal at measurement points across a measurement aperture. Each measured phase gradient is integrated to determine a vector having a direction from the measurement point to the signal emitter and an amplitude proportional to the received signal. A figure of merit is determined for each possible location of the signal emitter by integrating each vector with respect to a propagation path between the measurement point of the vector and the possible location of the signal emitter, and the location of the signal emitter is determined as the possible location of the signal emitter having the highest figure of merit.

Abstract: A wireless network having wireless network access devices may determine the location of newly added wireless network access devices.

Abstract: A mobile computer establishes a wireless communication session with a wireless access point of a computer network. The location of each wireless access point is known and obtainable either from a database on the network or from the access points themselves. The strengths of wireless signals passing between the mobile computer and multiple wireless access points of the network, including the access point with which the mobile computer has established the session are measured at multiple time intervals. The measurements may be taken at the mobile computer itself or at the wireless access points. The measured strength values are then weighted according to such factors as whether the mobile computer has already established a communication session with the access point from which the sample was taken, and how old the sample is. For each location, the weighted strength values obtained for access points in that location are summed.

Abstract: A method of locating a mobile telephone includes steps of receiving, transmitting, increasing and determining. In the receiving step, a first base station receives a call from a mobile telephone, the call including a dialed number and a TDMA signal. In the transmitting step, the base station transmits a control message to the mobile telephone when the dialed number meets a predetermined criterion, such as being 911. The control message instructs the mobile telephone to transmit the TDMA signal at a maximum power. In the increasing step, the mobile telephone increases the TDMA signal to maximum power in response to the control message. Then in the determining step, location information for the mobile telephone is determined based on at least one characteristic of the TDMA signal received at at least one of the first base station and other base stations.

Abstract: In a wireless location system, narrowband receivers are used in a mode, known as automatic synchronous or sequential tuning, in which the receivers are tuned sequentially and in unison to a plurality of predefined RF channels. Signal transmissions of interest in these channels are digitally recorded and used in location processing. A location record or report is generated to identify an estimated location of one or more wireless transmitters. The identity of the located transmitter(s) is determined by matching the location record to data indicating which wireless transmitters were in use at a time corresponding to the location record, and which cell sites and RF channels were used by each wireless transmitter. This method is especially suited for voice or traffic channel tracking of wireless mobile transmitters, such as cellular telephones.

Abstract: The location of a cellular telephone handset relative to the sites of two pairs of fixed cellular transceivers is determined by responding to the phase difference of radio waves the handset emits, as coupled to the sites. The phase difference is detected by supplying replicas of the waves received at the first and second sites to first and second electro-acoustical transducers at opposite ends of a Bragg cell. One Bragg cell is thus associated with each pair of cellular transceivers. A laser beam incident on each Bragg cell is deflected by a moving optical grating resulting from the interaction of acoustic waves applied by the electro-acoustical transducers to the particular Bragg cell. The laser beam deflection angle for each Bragg cell determines the relative phase angle of the acoustic waves in that cell.

Abstract: A position determination system of a hybrid method, which is capable of complementing the problems of a position determination method, in which a global positioning system (GPS) is used, and a position determination method, in which a mobile communication signal is used, by combining the above two methods with each other, is provided. Also, it is possible to improve the reliability and the correctness in determining the position of a mobile communication terminal using a dispersing type hybrid position calculation method and a centralized hybrid position calculation method.

Abstract: A system and process for determining the location of persons and objects using transmitters (TXs) that transmit location messages to at least one receiver connected to a computer, in a network of computers. The TXs are small, battery-powered, radio frequency transmitters carried by the person or object whose location is being tracked. The location message signals are picked up by one or more receivers (RXs) scattered throughout an environment. Each TX transmits a code with a unique identifier, and each RX also has a unique identifier. The RXs measure the signal strength of each location message transmission. Each RX is connected to a computer, which is in turn connected to a network. The RX computers send the data messages including the TX identifier, radio signal strength, and RX identifier to a central computer via the network. The central computer uses this information to determine the location of the TXs.

Abstract: A system for locating the position of an emitter emitting a signal having time domain features is described. At least two platforms are used. Both have a receiver for detecting the emitter signal, an FFT channelizer to act as a bandpass filter for extracting the time domain features from the emitter signal, and a thresholder for thresholding the time domain signal. An FFT transform and a correlator using templates further extract frequency domain markers identifying the emitter.