EP1257841A2 - Localisation d'une unite mobile au moyen de signaux satellite traites de maniere coherente associes a des signaux de balises stationnaires - Google Patents

Localisation d'une unite mobile au moyen de signaux satellite traites de maniere coherente associes a des signaux de balises stationnaires

Info

Publication number
EP1257841A2
EP1257841A2 EP00984480A EP00984480A EP1257841A2 EP 1257841 A2 EP1257841 A2 EP 1257841A2 EP 00984480 A EP00984480 A EP 00984480A EP 00984480 A EP00984480 A EP 00984480A EP 1257841 A2 EP1257841 A2 EP 1257841A2
Authority
EP
European Patent Office
Prior art keywords
beacon
signal
mobile
mobile unit
beacons
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP00984480A
Other languages
German (de)
English (en)
Other versions
EP1257841A4 (fr
Inventor
Joseph Nir
Baruch Shayevits
Hanoch Cohen
Oleg Perelmuter
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Cellguide Ltd
Original Assignee
Cellguide Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US09/585,622 external-priority patent/US6285316B1/en
Priority claimed from US09/585,619 external-priority patent/US6985542B1/en
Application filed by Cellguide Ltd filed Critical Cellguide Ltd
Publication of EP1257841A2 publication Critical patent/EP1257841A2/fr
Publication of EP1257841A4 publication Critical patent/EP1257841A4/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S1/00—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith
    • G01S1/02—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith using radio waves
    • G01S1/68—Marker, boundary, call-sign, or like beacons transmitting signals not carrying directional information
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13—Receivers
    • G01S19/24—Acquisition or tracking or demodulation of signals transmitted by the system
    • G01S19/29—Acquisition or tracking or demodulation of signals transmitted by the system carrier including Doppler, related
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/03—Cooperating elements; Interaction or communication between different cooperating elements or between cooperating elements and receivers
    • G01S19/10—Cooperating elements; Interaction or communication between different cooperating elements or between cooperating elements and receivers providing dedicated supplementary positioning signals
    • G01S19/12—Cooperating elements; Interaction or communication between different cooperating elements or between cooperating elements and receivers providing dedicated supplementary positioning signals wherein the cooperating elements are telecommunication base stations
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13—Receivers
    • G01S19/24—Acquisition or tracking or demodulation of signals transmitted by the system
    • G01S19/25—Acquisition or tracking or demodulation of signals transmitted by the system involving aiding data received from a cooperating element, e.g. assisted GPS
    • G01S19/252—Employing an initial estimate of location in generating assistance data
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13—Receivers
    • G01S19/24—Acquisition or tracking or demodulation of signals transmitted by the system
    • G01S19/25—Acquisition or tracking or demodulation of signals transmitted by the system involving aiding data received from a cooperating element, e.g. assisted GPS
    • G01S19/256—Acquisition or tracking or demodulation of signals transmitted by the system involving aiding data received from a cooperating element, e.g. assisted GPS relating to timing, e.g. time of week, code phase, timing offset

Definitions

  • the present invention relates to positioning systems for portable radio transceivers, and, more particularly, to a positioning system for a mobile unit of a wireless communications network, based on signals from a satellite network such as the Global Positioning System (GPS) and on signals from the base stations of the wireless communications network.
  • the Global Positioning System is a system of low Earth orbit satellites that transmit standard signals that can be used to establish the location of a user equipped with a suitable GPS receiver.
  • the signals are "C/A codes” that are pseudorandom noise (PN) sequences transmitted at a chip rate of 1023 KHz and a repetition period of 1023 chips, so that each frame of the PN sequence includes 1023 chips.
  • PN pseudorandom noise
  • Satellite Data Message Supeiposed on the PN sequences transmitted by a GPS satellite is a Satellite Data Message, transmitted every 30 seconds at a rate of 50 bits per second. Each bit (+1 or -1) of the Satellite Data Message is modulated onto the satellite's signal by multiplying 20 consecutive frames of the PN sequence by the bit.
  • the first 900 bits of the Satellite Data Message includes the satellite ephemeris and time model for the respective satellite.
  • the remaining 600 bits of the Satellite Data Message include a portion of the GPS almanac, which is a 15,000 bit block of coarse ephemeris and time model data for the entire GPS system.
  • bits 1-8, bits 301-308, bits 601-608, bits 901-908 and bits 1201-1208 of every Satellite Data Message are identical 8-bit (160 millisecond) headers that are invariant in time and that are identical for all the GPS satellites; and bits 31-60, bits 331-360, bits 631-660, bits 931-960 and bits 1231-1260 of every Satellite Data Message are 30-bit (600 millisecond) handover words that are time-variant (these handover words include representations of the time of the week), but that, like the headers, are identical for all the GPS satellites.
  • a GPS receiver acquires and tracks the signals from at least four GPS satellites, by correlating the received signal with the satellites' respective PN sequences and locking on to the correlation peaks.
  • the GPS receiver decodes the ephemeris and time model, for each acquired satellite, from the respective Satellite Data Messages. These models include sufficient ephemeris data to enable the GPS receiver to compute the satellite's positions.
  • the correlation peaks obtained during the continued tracking of the satellites provide measured times of arrival of these PN sequence frames.
  • the differences between an arbitrary reference time and measured times of arrival, multiplied by the speed of light, are pseudoranges p from the satellites to the GPS receiver.
  • the reference time is the time at which the satellites commenced transmission of their respective PN sequences, as measured by the GPS receiver clock, which in general is offset from the GPS system clock by an unknown time offset.
  • the satellites are sufficiently far from the GPS receiver that these equations can be linearized in x, y and z with no loss of accuracy.
  • 5,365,450 which is incorporated by reference for all purposes as if fully set forth herein, teach the provision of the Satellite Data Messages to a GPS receiver integrated into a mobile unit, such as a cellular telephone, of a wireless communications network such as a cellular telephone network, by transmitting the Satellite Data Messages to the mobile unit from a base station of the network via the control channel of the network.
  • the Satellite Data Message is 30 seconds long, so even under ideal reception conditions with parallel processing of the signals from all the satellites in view, it necessarily takes more than 30 seconds to get a GPS position fix. Prior knowledge of the Satellite Data Message reduces this time to under 10 seconds.
  • a mobile receiver of a wireless communications network.
  • the remote unit and a base unit at a fixed location both receive signals on a control channel from three or more base transceiver stations (BTSs), and both correlate invariant portions of the control channel signals.
  • BTSs base transceiver stations
  • Compact descriptions of the correlation peaks, such as low order polynomial fits, are transmitted to a central processor by both the base unit and the remote unit.
  • the central processor recovers, from the correlation peaks, the time offsets of the BTS transmissions to the base and remote units.
  • the central processor Given the (fixed) locations of the BTSs and the base unit, the central processor computes the position of the remote unit, essentially by riangulation, and transmits that location to the remote unit.
  • a GPS positioning system is predicated on the GPS receiver having a clear line of sight to at least four GPS satellites. This often is not the case in an urban environment. Urban environments commonly have cellular telephone networks installed, so in principle the system taught by Duffet-Smith et al. could be used for locating a mobile transceiver configured as a cellular telephone; but cellular telephones generally are in simultaneous contact with at most two base stations. Sheynblatt, in U. S. Patent No.
  • Such synchronization is optional under the GSM cellular standard.
  • a system and method for locating a mobile unit of a wireless communications network for example a mobile cellular telephone in a cluttered and noisy urban environment, that derives the location of the mobile unit from signals received sequentially from low Earth orbit satellites such as GPS satellites and from base stations of the communications network, without requiring that the BTSs be mutually synchronized.
  • a method for determining a pseudorange, and a rate of change thereof, to a beacon that transmits a signal including a plurality of blocks, each block including a plurality of frames of a pseudonoise sequence, each block being multiplied by a bit of a data sequence, the signal being shifted relative to a nominal frequency by a frequency shift, the method including the steps of: (a) receiving the signal; (b) digitizing the received signal, thereby producing a digitized signal including a plurality of bits; (c) arranging the digitized signal as columns of an input matrix that includes a plurality of rows, each column including consecutive the bits of the digitized signal that correspond to an integral number of frames of the pseudonoise sequence; and (d) performing a discrete orthogonal transform on each row of the input matrix, thereby producing a transformed matrix.
  • each beacon transmitting a respective signal including a plurality of blocks, each block including a plurality of frames of a pseudonoise sequence, each block being multiplied by a bit of a data sequence, the pseudonoise sequences and the data sequences being uniquely associated with respective satellites, all the pseudonoise sequences being of equal length, the pseudonoise sequences being mutually orthogonal, the method including the steps of: (a) receiving the transmitted signals collectively as a received signal; (b) digitizing the received signal, thereby producing a digitized signal including a plurality of bits; and (c) for each beacon, multiplying groups of the bits of the digitized signal, that correspond to the blocks of the signal transmitted by the each beacon, by respective bits of the data sequence of the each beacon.
  • a receiver for receiving a signal transmitted by a beacon including a plurality of frames of a pseudonoise sequence, including: (a) an antenna for receiving the transmitted signal; (b) a mechanism for digitizing the received signal to produce a digitized signal including a plurality of bits; (c) a memory for storing the digitized signal as columns of a matrix that includes a plurality of rows, each column including consecutive the bits of the digitized signal that correspond to an integral number of frames of the pseudonoise sequence; and (d) a processor for performing a discrete orthogonal transform on each of the rows of the matrix.
  • a locator system for locating a mobile unit including: (a) at least one beacon having a respective pseudonoise sequence and a respective data sequence, each data sequence including a plurality of bits, each at least one beacon operative to transmit a respective transmitted signal, each respective transmitted signal including a plurality of blocks, each block including a plurality of frames of the respective pseudonoise sequence, each block being multiplied by a bit of the respective data sequence, (b) a reference unit including: (i) a reference unit receiver for: (A) receiving the at least one transmitted signal as a reference unit received signal, and (B) recovering the at least one data sequence from the respective reference unit received signal, and (ii) a transmitter for transmitting the at least one data sequence to the at least one mobile unit; and (c) in the mobile unit: (i) a first mobile unit receiver for receiving the at least one data sequence, and (ii) a second mobile unit receiver including: (A) an antenna for receiving the at least one transmitted signal collectively as
  • a method for determining a location of a receiver including the steps of: (a) providing a plurality of beacons having respective pseudonoise sequences, all the pseudonoise sequences being of equal length; (b) transmitting, by each beacon, a respective signal including a plurality of frames of the respective pseudonoise sequence; (c) receiving the transmitted signals collectively as a received signal, by the receiver; (d) inferring, for each beacon, a pseudorange and a rate of change of the pseudorange; and (e) inferring the location of the receiver from the pseudoranges and from the rates of change of the pseudoranges.
  • a method for determining a pseudorange, and a rate of change thereof, to a beacon that transmits a signal including a plurality of blocks, each block including a plurality of frames of a pseudonoise sequence, each block being multiplied by a bit of a data sequence, the signal being shifted relative to a nominal frequency by a Doppler frequency shift, the method including the steps of: (a) receiving the signal; (b) digitizing the received signal, thereby producing a digitized signal including a plurality of bits; and (c) applying a matched filter algorithm to the digitized signal to extract therefrom the pseudorange and the rate of change of the pseudorange, the matched filter algorithm including: (i) demodulating the digitized signal relative to the data sequence.
  • a method for locating a mobile unit including the steps of: (a) providing a plurality of asynchronous stationary beacons, each stationary beacon transmitting a respective stationary beacon signal; (b) providing a plurality of mobile beacons moving on known respective trajectories, each mobile beacon transmitting a respective mobile beacon signal, all the mobile beacons being mutually synchronized; (c) for each of at least one of the stationary beacons: (i) receiving the respective stationary beacon signal, by the mobile unit, and (ii) inferring, from the respective stationary beacon signal, at least one parameter related to a range to the each stationary beacon; (d) for each of at least one of the mobile beacons: (i) receiving the respective mobile beacon signal, by the mobile unit, and (ii) inferring, from the respective mobile beacon signal, at least one parameter related to a range to the each mobile beacon; (e) synchronizing the mobile unit and the stationary beacons to the mobile beacons by steps including: (i) providing, for each stationary beacon, a
  • a method for tracking a mobile unit including the steps of: (a) providing a plurality of beacons, each beacon transmitting a respective ranging signal; (b) obtaining an initial estimate of a location of the mobile unit; (c) receiving, by the mobile unit, one of the ranging signals; (d) inferring, from the ranging signal, at least one parameter related to a range to the beacon that transmitted the ranging signal; and (e) obtaining an updated estimate of the location of the mobile unit, based on an initial state estimate that includes the initial estimate of the location and on an update measurement that includes the at least one parameter.
  • a locator system for locating a mobile unit including: (a) a plurality of asynchronous stationary beacons, each stationary beacon being operative to transmit a respective stationary beacon signal; (b) a plurality of mobile beacons, each mobile beacon operative to transmit a respective mobile beacon signal while moving on a known respective trajectory, all the mobile beacons being mutually synchronized; and (c) in the mobile unit: (i) a mobile unit clock for producing a mobile unit timing signal; (ii) a first mobile unit receiver for receiving and digitizing the stationary beacon signals; (iii) a second mobile unit receiver for receiving and digitizing the mobile beacon signals, thereby producing corresponding digitized mobile beacon signal; (iv) a memory for storing the digitized mobile beacon signal; (v) a mobile unit processor for transforming each of the stationary beacon signals into a corresponding stationary beacon pseudorange, and for transforming each of the digitized mobile beacon signals into a corresponding mobile beacon pseudorange subsequent to the storing of the each digit
  • a locator system for locating a mobile unit including: (a) a plurality of beacons, each beacon transmitting a respective ranging signal; and (b) in the mobile unit: (i) a mechanism for obtaining an initial estimate of a location of the mobile unit, (ii) a receiver for receiving the ranging signals, (iii) a processor for inferring, from one of the ranging signal, at least one parameter related to a range to the beacon that transmitted the ranging signal, and (iv) an updating mechanism for updating the location estimate, based on an update measurement that includes the at least one parameter.
  • a method for tracking a mobile unit including the steps of: (a) providing a plurality of mobile beacons, each mobile beacon transmitting a respective ranging signal; (b) providing a plurality of stationary beacons, each stationary beacon transmitting a respective ranging signal; (c) obtaining an initial estimate of a location of the mobile unit; (d) receiving, by the mobile unit, a first ranging signal from a respective beacon of one of the pluralities of beacons; (e) inferring, from the first ranging signal, at least one parameter related to a range to the beacon that transmitted the first ranging signal; (f) obtaining a first updated estimate of the location of the mobile unit, based on the initial location and on the at least one parameter that is related to the range to the beacon that transmitted the first ranging signal; (g) receiving, by the mobile unit, a second ranging signal from a respective beacon of another of the pluralities of beacons; (h) inferring, from the second ranging signal, at least one parameter related to
  • a locator system for locating a mobile unit including: (a) a plurality of mobile beacons, each mobile beacon transmitting a respective ranging signal; (b) a plurality of stationary beacons, each stationary beacon transmitting a respective ranging signal; and (c) in the mobile unit: (i) a mechanism for obtaining an initial estimate of a location of the mobile unit, (ii) a receiver for receiving the ranging signals, (iii) a processor for inferring, from each of the ranging signals, at least one parameter related to a range to the beacon that transmitted the ranging signal, and (iv) an updating mechanism for updating the initial location estimate, using the at least one parameter that is related to the range to a beacon of one of the pluralities of beacons, thereby providing a first updated estimate of the location of the mobile unit, and for updating the first updated estimate, using the at least one parameter that is related to the range to a beacon of another of the pluralities of beacons.
  • the present invention includes methods and systems that enable a mobile unit to determine its location by appropriate processing of signals received from mobile beacons and stationary beacons.
  • a beacon is a device that includes a transmitter that transmits a signal, typically a radio frequency signal, that the mobile unit receives and then uses to determine its own location.
  • Some of the beacons are stationary, meaning that these beacons are in fixed and known locations.
  • Other beacons are mobile, meaning that these beacons move along known trajectories, such that at any time, the instantaneous locations of the relevant mobile beacons are known.
  • the mobile unit is a cellular telephone
  • the stationary beacons are base transceiver stations of a cellular telephone network
  • the mobile beacons are satellites of a low-Earth-orbit-satellite-based positioning system such as the GPS system and the Russian GLONASS system, the trajectories of the mobile beacons then being the orbits of the satellites, as described by the satellite ephemeris and time models.
  • the scope of the present invention includes any suitable beacons.
  • the stationary beacons may be special purpose beacons set up specifically to enable the tracking of a mobile unit, and the mobile beacons may be aircraft flying along known trajectories.
  • the mobile unit receives timing signals from the mobile and stationary beacons.
  • the timing signals are successive PN frames, modulated by the Satellite Data Messages.
  • the timing signals are synchronization burst sequences transmitted in the cellular network control channel.
  • At least one reference unit is provided, for determining offsets between the BTSs and GPS time.
  • One reference unit is associated with one or more BTSs.
  • Each reference unit includes a GPS-based time reference module for receiving the PN frames from the GPS satellites and cross-correlating them with local copies of the PN sequences to determine GPS time, a cellular communications module for receiving the synchronization burst sequences from the associated BTSs, and a synchronization module for determining the timing offsets of the associated BTSs relative to GPS time.
  • the cellular telephone network is provided with a locator service center, and the reference units transmit the timing offsets to the mobile unit via the locator service center.
  • one of the reference units is designated as a master reference unit that also transmits the Satellite Data Messages to the mobile unit via the locator service center.
  • the mobile unit is synchronized to the cellular network in the conventional manner. This allows the mobile unit to also be synchronized approximately to the GPS network: having received the BTS timing offsets from the reference units via the locator service center, the mobile unit computes the time offset between its own clock and GPS time to within about 30 microseconds.
  • the mobile unit receives the satellite timing signals collectively from the GPS satellites that are in view, digitizes the combined signal, and applies matched filter algorithms to the combined signal to extract pseudoranges and rates of change of pseudoranges from the combined signal, as follows. Successive frames of the digitized combined signal are arranged as columns of a matrix. As many instances of the matrix are formed as there are satellites in view. That the mobile unit is approximately synchronized with the GPS network allows each matrix instance to be demodulated, with respect to the Satellite Data Message of the corresponding satellite, by multiplying groups of columns of the matrix instance by corresponding bits of the Satellite Data Message of the corresponding satellites.
  • any PN frames may be used to form the instances of the matrix; otherwise, only those PN frames, that correspond to bits of the Satellite Data Messages that are common to all satellites, are used.
  • the rows of the matrices are transformed using a discrete orthogonal transform, preferably a discrete Fourier transform.
  • the elements of the matrices are multiplied by respective Doppler compensation factors.
  • the columns of the matrices are convolved with the PN sequences of the in-view satellites to provide, for each in-view satellite, a signal ambiguity function matrix.
  • the squared magnitudes of the elements of these matrices include local peaks, the row and column coordinates of which correspond to candidate hypotheses for the pseudoranges to the corresponding satellites and to the rates of change of these pseudoranges. This procedure is repeated several times to provide several signal ambiguity function matrices for each in-view satellite. Then, for each in-view satellite, the best hypothesis is chosen, for example, by integrating the matrices noncoherently and then identifying the most likely peak in the sum; or by passing the coordinates of all the peaks of the matrices to a "track before detect" algorithm. In either case, the peaks are identified using a constant false alarm rate detection scheme.
  • the pseudoranges to stationary beacons are simply the differences between the measured times of arrival of the synchronization burst sequences and the transmission times of the synchronization burst sequences according to the GPS system clock, multiplied by the speed of light. Note that, because the mobile unit has received the time offsets between the BTS clocks and the GPS system clock, from the reference units via the locator service center, the mobile unit can refer these transmission times to the GPS system clock. Note also that, as a consequence, the pseudoranges to the BTSs are with reference to the same range offset, ,, as applies to the GPS satellites.
  • each stationary beacon pseudorange is acquired by the mobile unit, and as each mobile beacon pseudorange - pseudorange rate pair is acquired by the mobile unit, these data are input as update measurements to a dynamic estimator to produce an updated estimate of the location of the mobile unit.
  • the dynamic estimator is based on a linear optimal estimator, such as a Kalman filter.
  • the dynamic estimator requires an initial estimate of the location of the mobile unit. This initial estimate is obtained by triangulation.
  • the location of a predefined reference point such as the nearest stationary beacon, may be used as the initial estimate of the mobile unit's location.
  • FIG. 1 is a block diagram of a mobile unit of the present invention
  • FIG. 2 is a schematic diagram of a locator system of the present invention
  • FIG. 3 is a block diagram of a reference unit of the present invention.
  • FIG. 4 is a flow chart of the joint estimation of position from satellite pseudoranges, rates of change of satellite pseudoranges and base station pseudoranges.
  • the present invention is of a system and method for locating a mobile unit, for example a mobile unit of a wireless communications system, based on timing signals, both from mobile beacons such as GPS satellites and from stationary beacons such as base stations of the wireless communications system.
  • the present invention can be used to locate a suitably equipped cellular telephone in an environment, such as an urban environment, in which it is difficult to establish simultaneous lines of sight to four or more GPS satellites.
  • FIG. 1 is a partial high level block diagram of a mobile unit 10 of the present invention.
  • Mobile unit 10 includes an antenna 12 for receiving RF signals transmitted by GPS satellites, a downconverter 14 for downconverting the RF signals received from the GPS satellites to an intermediate frequency (IF), a digitizer 16 for digitizing the IF signals, a clock 22 for providing local timing signals, a memory 18 for storing the digitized GPS signals , and a GPS processor 20 for processing the signals stored in memory 18.
  • IF intermediate frequency
  • a digitizer 16 for digitizing the IF signals
  • a clock 22 for providing local timing signals
  • memory 18 for storing the digitized GPS signals
  • GPS processor 20 for processing the signals stored in memory 18.
  • Mobile unit 10 also includes an antenna 24 for exchanging RF signals with BTSs of a cellular telephone network, a cellular modem 26 for downconverting and digitizing the control channel RF signals received from the BTSs, a memory 27 for storing the digitized BTS signals, and a cellular processor 28 for processing the digitized BTS signals with reference to timing signals from clock 22, as described below.
  • the outputs of GPS processor 20 and cellular processor 28 are reconciled in a joint estimator 30, as described below, to produce a joint estimate of the location of the mobile unit of which mobile unit 10 is a part.
  • GPS processor 20, cellular processor 28 and joint estimator 30 function under the overall supervision of a management unit 29.
  • management unit 29 formulates requests for supplemental data, and, using cellular modem 26 and antenna 24, transmits these requests as RF signals to the BTSs, as described below.
  • FIG 2 is a schematic diagram of a locator system 40 of the present invention.
  • Locator system 40 is based on a conventional cellular telephone network 42 that includes multiple BTSs 44 , and on the GPS system, represented in Figure 2 by satellites 70.
  • the terrestrial component of locator system 40 adds to cellular telephone network 42 a locator service center 46 and a multitude of reference units 50, at fixed and known locations.
  • Each reference unit 50 is associated with one or more BTSs 44, and communicates with those BTSs 44 and, via the nearest of those BTSs 44, with service center 46.
  • Mobile unit 10 using antenna 24 and cellular modem 26, also receives messages from service center 46 via the nearest BTS 44, as described below.
  • FIG. 3 is a high level block diagram of reference unit 50.
  • Reference unit 50 includes a cellular communications module (CCM) 52 for communicating with service center 46 via cellular network 42, a GPS-based time reference module 66, and a synchronization module 60 for synchronizing CCM 52 to GPS-based time reference module 66 as described below.
  • CCM 52 includes both transmission functionality 54 and reception functionality 56, via an antenna 58.
  • GPS-based time reference module 66 receives GPS satellite signals via an antenna 68.
  • Synchronization module 60 includes both a clock 64 for providing reference timing signals and a processor 62 for establishing timing offsets between the GPS system and the BTSs 44 that are associated with reference unit 50, as described below.
  • each reference unit 50 determines these timing offsets and to transmit these timing offset to locator service center 46.
  • one of reference units 50 is designated as a master reference unit.
  • the master reference unit has the additional function of receiving the Satellite Data Messages from satellites 70 and transmitting these Satellite Data Messages to locator service center 46.
  • Locator service center 46 is a node of cellular telephone network 42 whose function is to coordinate communications between mobile unit 10 and cellular telephone network 42 that relate to the self-location functionality of mobile unit 10.
  • locator service center 46 upon receipt of a query from mobile unit 10, transmits to mobile unit 10 supplemental data such as the timing offsets between the GPS system and one or more BTSs 44 and optionally the Satellite Data Messages of in-view satellites 70.
  • supplemental data such as the timing offsets between the GPS system and one or more BTSs 44 and optionally the Satellite Data Messages of in-view satellites 70.
  • the functionality of joint estimator 30 may reside in location service center 46, with the outputs of GPS processor 20 and cellular processor 28 being transmitted to location service center 46 for reconciliation.
  • the signal received by mobile unit 10 from the GPS system, as a function of time t, is a sum of the signals G ⁇ t) transmitted by GPS satellites 70 that are in view at time t.
  • the signal received by mobile unit 10 from any one satellite 70, indexed by an index j, is in the form
  • G j ⁇ t) ⁇ ⁇ E> ⁇ t- ⁇ / )g 7 (t- ⁇ 7 )exp[/ ⁇ (t- ⁇ / )j
  • / is the square root of -1
  • ⁇ is the true one-way propagation time of radio waves from the satellite to mobile unit 10
  • D j ⁇ t- ⁇ j) is the Satellite Data Message of satellite y at time t- ⁇ /
  • g j ⁇ t- ⁇ j) is the PN sequence of satellite at time t- ⁇
  • exp[z ' ⁇ (t- ⁇ / )j is a Doppler factor whose Doppler frequency ⁇ depends on the radial component of the velocity of satellite / relative to mobile unit 10, on the bias of clock 22, and on other imperfections in mobile unit 10.
  • the total signal G ⁇ i) received by mobile unit 10 is the sum of these signals, ⁇ T G (t) .
  • US 5,663,734 As in US 5,663,734, several hundred seconds worth of a digitized total GPS signal is stored in memory 18 and then processed by GPS processor 20.
  • GPS processor 20 One difference between US 5,663,734 and the GPS processing of the present invention is that according to the present invention, groups of many more than 5 to 10 PN sequence frames are processed coherently.
  • the total signal received by mobile unit 10 is oversampled by digitizer 16, starting at an initial reception time to, typically at a sampling rate of between two and four samples per chip. With four samples per chip, there are a total of 4x1023-4092 samples per frame. For each in-view satellite 70, indexed by index y, these samples are stored as successive columns of a matrix Mjj that, in the case of a sampling rate of four samples per chip, has 4092 rows and as many columns as the number of consecutive frames included in the computation: the first column of M j , matrix elements through M;J ⁇ 4092,1) are the first 4092 samples, corresponding to the first millisecond's worth of data; the second column of Mj j , matrix elements #(l,2) through Mj j ⁇ 4092,2), are the second 4092 samples, corresponding to the second millisecond's worth of data; etc., through a number of columns n equal to the number of frames of data that are stored in memory 18, at one millisecond per frame.
  • the first processing step is to demodulate each matrix Mj j , i.e., to remove the influence of Satellite Data Message D j . This is done by multiplying groups of columns of Mj j by the corresponding bits of D j ⁇ t-x ). A necessary prerequisite for this demodulation is for the bits of D j to be aligned with the columns of M j to within about one millisecond. This alignment is referred to herein as "approximate synchronization" of mobile unit 10 with the GPS system.
  • Cellular telephone network 42 may be synchronized to the GPS system clock in any case, for example, if cellular telephone network operates according to the CDMA IS-95 standard. Mobile unit 10 is synchronized to cellular telephone network 42 in the conventional manner. Because cellular telephone network 42 is time-aligned (synchronized) with GPS system time, mobile unit 10 also is synchronized to GPS system time and therefore is able to demodulate matrix M j relative to Satellite Data Message D j .
  • synchronization module 60 determines the time offset between that BTS 44 and the GPS system with reference to clock 64.
  • the propagation time from each associated BTS 44 to reference unit 50 also is known, so the time offset is referred to the time at which that BTS 44 transmitted the synchronization burst sequence, and not the time at which reference unit 50 received the synchronization burst sequence.
  • CCM 52 then transmits this time offset to locator service center 46. This is done for the synchronization burst sequence of each associated BTS 44, so that locator service center 46 always has a current list of time offsets of all BTSs 44 from the GPS system.
  • mobile unit 10 receives the current time offsets of the relevant BTSs 44 from locator service center 46 on request.
  • the time offset of the nearest BTS 44 from the GPS system is used by mobile unit 10 to correct the nominal transmission times of the synchronization burst sequences from the nearest BTS 44 for this offset, and so to obtain an estimate of its own time offset To from GPS system time to within 30 microseconds.
  • the time offsets of BTSs 44 from the GPS system also are used to obtain BTS pseudoranges that are referred to range offset c / ,, as described below. If the frames that are used to construct matrix Mj j correspond to Satellite Data
  • mobile unit 10 either knows these bits a priori (in the case of header bits) or computes these bits based on the time of the week (in the case of handover word bits).
  • mobile unit 10 sends a request to locator service center 46 to obtain Satellite Data Message D, so that the satellite-dependent bits of Satellite Data Message D j can be used to demodulate matrix M j .
  • the second processing step is to transform each matrix Mj into a matrix M J J by performing a discrete orthogonal transform on each of the rows of matrix Mj j , thereby transforming the rows from the time domain to the frequency domain, so that matrices M JJ J are in a mixed time-frequency domain.
  • the most preferred discrete orthogonal transform is the discrete Fourier transform, although the scope of the present invention includes other transforms, such as the Walsh-Hadamard transform, the various kinds of Wavelet transforms and the Flartley transform.
  • the third processing step is the multiplication of the elements of each matrix M JJ J by Doppler compensation factors.
  • the form of the Doppler compensation factor is the Doppler compensation factor
  • the fourth processing step is to convolve each of the columns of each matrix
  • the preferred convolution method is the well-known fast convolution method, also used by Krasner in US 5,663,734: perform a discrete Fourier transform on a column of matrix M JJ J, multiply the transformed column by the discrete Fourier transform of the PN sequence, and invert the discrete
  • V m J transformed column of M JJ J appropriately shifting the discrete Fourier transform of the PN sequence prior to the multiplication of the transformed column by the discrete Fourier transform of the PN sequence.
  • the matrix elements of Mj are complex.
  • the overall appearance of matrix M j in terms of the squared magnitudes of its elements, is a set of peaks above a general background level.
  • the row coordinate of a peak is its pseudorange (units of distance) and the column coordinate (units of frequency) of a peak is proportional to the rate of change of its pseudorange (units of velocity).
  • matrix Mj has one frame per column, it also is possible to construct matrix M j with more than one frame per column, as long as an integral number of frames are used per column. Using one frame per column gives the optimal resolution for determining the rates of change of the pseudoranges.
  • a constant false alarm rate detection scheme is used to identify the peaks.
  • the detection scheme is based on an adaptive threshold, based on a background level that is obtained, matrix element by matrix element, by averaging the squared magnitudes of all the matrix elements in a window (for example, an 8x8 window or a 16x16 window) around the target matrix element.
  • the set of matrix elements, whose squared magnitudes exceed their local average by a threshold factor, is in the form of isolated clusters of matrix elements, with each cluster corresponding to one peak.
  • the coordinates of the peaks are the centroids of the clusters, weighted by the magnitudes of the matrix elements in the clusters.
  • the threshold factor is determined by the required maximum false alarm rate, as is well-known in the art.
  • the output of this procedure is a set of hypotheses for the pseudorange p 7 and its rate of change dpjdt associated with the initial reception time to.
  • the hypothesis associated with the peak most likely to be the most reliable measure of p,- and dpjdt, for example, the highest peak could be selected to provide the coordinates that determine j and dp j ldt.
  • several instances of the matrices M j are generated.
  • Preferably, between five and ten such instances of each matrix Mj are so generated.
  • Subsequent processing is directed towards obtaining, for satellite j, values of P j and dpjdt that are based on all the instances of M j processed collectively.
  • One method of processing the instances of M j collectively is to integrate them noncoherently.
  • standard noncoherent integration the matrix elements of all the instances are replaced by their squared magnitudes; the instances are added to each other, matrix element by matrix element, to produce a sum matrix; the false alarm detection scheme described above is used to identify the peaks of the sum matrix; and the coordinates of the peak most likely to be the most reliable measure of j and dp ⁇ dt, for example, the highest peak, are taken as the values of p- and dpjdt.
  • binary noncoherent integration the matrix elements of all the instances are replaced by their squared magnitudes, but then the constant false alarm detection scheme is used to compare each matrix element with a threshold.
  • Matrix elements that exceed the threshold are replaced by ones, and all other matrix elements are replaced by zeros.
  • the instances now are added to each other, matrix element by matrix element, to produce a sum matrix, and a second threshold is applied to the sum matrix to identify its peaks. Again, the coordinates of the peak, of the sum matrix, that is most likely to represent the most reliable measure of p, and dpjdt, are used as the values of P j and dpjdt.
  • Another way to obtain values of p y and dpjdt that are based on all the instances of Mj processed collectively is to replace the matrix elements of all the instances with their squared magnitudes, as in noncoherent integration, but then to apply the constant false alarm rate detection scheme separately to each instance, to obtain, for each instance, a set of hypotheses for p_, and dpjdt. These hypotheses and their associated start times are input to a "track before detect” identification scheme to identify the most likely hypothesis. "Track before detect” is a method that is well known in radar technology for identifying targets in a low signal-to-noise environment. See, for example, the book by Fred E. Nathanson cited above.
  • the pseudoranges to BTSs 44 are the differences between the measured times of arrival of the synchronization burst sequences and the nominal transmission times of the synchronization burst sequences according to the GPS system clock. If cellular telephone network 42 is synchronized to the GPS system clock, then the nominal transmission times of the synchronization burst sequences, according to clock 22, are offset from their true times by the same time offset, To, as the time offset by which the nominal transmission times of the PN sequences by satellites 70, according to clock 22, are offset from their true times. As a result, all the pseudoranges, both to satellites 70 and to BTSs 44, share the same range offset ,.
  • mobile unit 10 obtains the time offsets of BTSs 44 from the GPS system from locator service center 46, as described above in the context of the approximate synchronization of mobile unit 10 with the GPS system for the purpose of demodulation. Mobile unit 10 then uses these time offsets to correct the times of arrival of the synchronization burst sequences from BTSs 44, as measured by clock 22, so that the pseudoranges to BTSs 44 are referred to the same range offset a as the pseudoranges to satellites 70.
  • the pseudoranges to the in-view satellites 70, the rates of change of the pseudoranges to the in-view satellites 70, and the pseudoranges to BTSs 44 are input to joint estimator 30.
  • mobile unit 10 In-between updates of r and v, mobile unit 10 is assumed to move in a known manner.
  • the model of the motion of mobile unit 10 used herein as an example is linear motion with additive random noise. Other models, such as motion constrained to be along a known road, also may be used.
  • the linear model of the motion of mobile unit 10 if the location vector of mobile unit 10 at time t ⁇ is r ⁇ . and the velocity vector of mobile unit 10 at time - ⁇ is V k - ⁇ , then the location and velocity vectors at time
  • the range bias C b is defined as the difference between the time measured by clock 22 and the GPS clocks, multiplied by the speed of light c, and the range drift C d is defined as d ⁇ c b )ldt.
  • the (eight component) navigation vector // is defined as the concatenation of r, v, Cb and C
  • This state vector obeys the propagation equation ek ⁇ A k- ⁇ k- ⁇ ' ⁇ - w k -1 the transition matrix is:
  • W k - ⁇ is the process noise.
  • M>* is defined via the model noise covariance matrix
  • RW X and RW y are the covariances of the process noise in the x and v directions (note that mobile unit 10 is assumed to move substantially in the ⁇ x,y) plane), modeled as random walks, and I is a range drift error covariance, modeled as white noise.
  • the superscript "+” refers to the a postiori estimate of P after the most recent update
  • the superscript "-" refers to the a priori estimate of P, before the next update.
  • the matrix H k that relates the state vector e to this measurement vector at time t /c is:
  • i' k is the a priori mobile unit 10 location vector, obtained by forward propagation as described above.
  • S is the position vector of satellite 70 at time t /c , obtained by GPS processor 20 using the satellite ephemeris and time model of satellite 70.
  • the matrix H k that relates the state vector e to this measurement vector at time is:
  • the a postiori navigation vector n k is obtained by adding the state vector e to the a priori navigation vector n k :
  • Xk ⁇ + ⁇ , yk -yX ⁇ y,
  • Z k + z k + ⁇ z,
  • v xk + v xk + ⁇ >v x ,
  • v yk + v yk + ⁇ v y ,
  • v zk + v zk +bv z
  • Figure 4 is a flow chart of the overall processing effected by joint estimator 30 to track the motion of mobile unit 10.
  • the processing is initialized (block 100) with an initial estimate of the navigation vector n, and by setting the diagonal elements of the covariance matrix P equal to initial values that reflect the initial standard deviations of the errors in r, v, C and c . How the initial estimate of n is obtained is discussed below.
  • joint estimator 30 determines whether a measurement vector z has been obtained from GPS processor 20 or from cellular processor 28. If a measurement has not been obtained, then joint estimator 30 propagates (block 104) the navigation vector it forward in time, as described above.
  • joint estimator uses the Kalman filter described above (block 106) to obtain an a postiori estimate of the navigation vector n. Note that this updating of n is based on a single new measurement, in contrast to the use of a Kalman filter in prior art GPS navigation, in which at least four independent simultaneous measurements are needed. This a postiori estimate is reported (block 108), and joint estimator 30 again checks for a new measurement vector z from GPS processor 20 or from cellular processor 28.
  • a static estimate is used as the initial estimate of r in block 100, and v is initially set to zero.
  • static estimation is meant that the estimation is performed under the assumption that mobile unit 10 did not move while the measurements were made and that the range offset c b also was stationary while the measurements were made.
  • the simplest “static" estimate of r is the location of a predefined reference point, such as the BTS 44 nearest to mobile unit 10. c b and Cd also are initialized to zero. This estimate is suitable for use in block 100 of Figure 4 if the first four measurements are satellite measurements, because the error in using the location of a terrestrial reference point is much smaller than the distances to the satellites.
  • Mathematical techniques for solving simultaneous quadratic and linear equations are well-known and need not be elaborated here.
  • the processing described above may be made both more accurate and more efficient.
  • the Doppler frequency shifts of the signals G j ⁇ t may be estimated more accurately.
  • the total Doppler frequency shift is the sum of three terms: the Doppler frequency shift due to the motion of satellite j, the Doppler frequency shift due to the motion of mobile unit 10, and a contribution from the drift of clock 22.
  • the first term can be computed from the ephemeris and time model of satellite j. Mobile unit 10 moves sufficiently slowly that the second term is negligible.
  • the main initial uncertainty in the total Doppler frequency shift lies in the third term; but this term may be inferred from the range drift component c of the navigation vector n.
  • mobile unit estimates the clock drift term of the total Doppler frequency shift by subtracting the computed Doppler frequency shift of the nearest BTS 44 from the apparent Doppler frequency shift that corresponds to the rate of change of the pseudorange to this one satellite 70.
  • This estimated clock drift term is added to the known Doppler frequency shifts due to the motion of the other satellites 70 to provide estimates of the total Doppler frequency shifts of the other satellites 70.

Landscapes

  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Position Fixing By Use Of Radio Waves (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Radio Relay Systems (AREA)

Abstract

La présente invention concerne un procédé et un système de localisation d'une unité mobile par rapport aux satellites d'un réseau de satellites, notamment le système mondial de localisation, et par rapport aux stations de base d'un réseau de communications sans fil. Chaque satellite émet un signal consistant en une série de trames d'une séquence de bruit pseudoaléatoire. Les trames d'un signal reçues du réseau de satellites par l'unité mobile sont disposées sous forme de colonnes d'une matrice et sont traitées de manière cohérente pour fournir des pseudodistances estimées et des taux de changement estimés de pseudodistances pour les satellites en vue. Le traitement cohérent consiste à exécuter une transformée orthogonale sur les rangées de la matrice, à multiplier les éléments de la matrice par les facteurs de compensation Doppler, puis, pour chaque satellite en vue, à convolutionner les colonnes de la matrice avec la séquence de bruit pseudoaléatoire du satellite en question. D'autres pseudodistances sont inférées à partir des séquences de rafales de synchronisation reçues par l'unité mobile d'une ou de plusieurs stations de base. Si les stations de base ne sont pas synchronisées entre elles, des unités de référence permettent de déterminer les décalages temporels entre les horloges des stations de bases et l'horloge du réseau de satellites, et de transmettre ces décalages temporels à l'unité mobile, de manière à ce que toutes les pseudodistances présentent la même polarisation par rapport à l'horloge du réseau de satellites. Les pseudodistances sont traitées et comparées par un estimateur dynamique, comprenant un estimateur optimal linéaire, tel qu'un filtre de Kalman, pour produire des estimations successives de la position de l'unité mobile au cours de son déplacement.
EP00984480A 2000-01-18 2000-12-18 Localisation d'une unite mobile au moyen de signaux satellite traites de maniere coherente associes a des signaux de balises stationnaires Withdrawn EP1257841A4 (fr)

Applications Claiming Priority (7)

Application Number Priority Date Filing Date Title
US585622 1996-01-16
US17628900P 2000-01-18 2000-01-18
US176289P 2000-01-18
US585619 2000-06-02
US09/585,622 US6285316B1 (en) 2000-06-02 2000-06-02 Locating a mobile unit using signals from both mobile beacons and stationary beacons
US09/585,619 US6985542B1 (en) 2000-06-02 2000-06-02 Coherent processing of satellite signals to locate a mobile unit
PCT/US2000/034306 WO2001053848A2 (fr) 2000-01-18 2000-12-18 Localisation d'une unite mobile au moyen de signaux satellite traites de maniere coherente associes a des signaux de balises stationnaires

Publications (2)

Publication Number Publication Date
EP1257841A2 true EP1257841A2 (fr) 2002-11-20
EP1257841A4 EP1257841A4 (fr) 2009-05-13

Family

ID=27390653

Family Applications (1)

Application Number Title Priority Date Filing Date
EP00984480A Withdrawn EP1257841A4 (fr) 2000-01-18 2000-12-18 Localisation d'une unite mobile au moyen de signaux satellite traites de maniere coherente associes a des signaux de balises stationnaires

Country Status (7)

Country Link
EP (1) EP1257841A4 (fr)
JP (1) JP2003520968A (fr)
KR (1) KR20020076254A (fr)
CN (1) CN1425226A (fr)
AU (1) AU2001221092A1 (fr)
IL (1) IL150417A0 (fr)
WO (1) WO2001053848A2 (fr)

Families Citing this family (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10105901A1 (de) * 2001-02-09 2002-08-14 Bosch Gmbh Robert Verfahren zur Ermittlung der Position eines Landfahrzeugs mit einem Navigationssystem und Vorrichtung zur Durchführung des Verfahrens
GB0121030D0 (en) 2001-08-30 2001-10-24 Nokia Corp Location services
EP1574875A1 (fr) * 2004-03-09 2005-09-14 Sony Ericsson Mobile Communications AB Récepteur GPS monté sur véhicules rapides
US7212155B2 (en) * 2004-05-07 2007-05-01 Navcom Technology, Inc. GPS navigation using successive differences of carrier-phase measurements
GB2416461B (en) * 2004-07-20 2009-07-08 Vodafone Plc System and method for tracing the whereabouts of mobile terminals in mobile communications systems
KR101042730B1 (ko) * 2006-03-06 2011-06-20 콸콤 인코포레이티드 측정 스티칭을 사용한 위치 결정 방법
EP2044798B1 (fr) * 2006-07-14 2010-07-07 Koninklijke Philips Electronics N.V. Procédé et système d'émission et de réception de balises
EP1901088A1 (fr) * 2006-09-18 2008-03-19 Cambridge Positioning Systems Limited Navigation de terminal mobile intégrée
DE102008035440B4 (de) * 2008-07-25 2010-12-09 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Vorrichtung und Verfahren zum Bestimmen der Entfernung und/oder Orientierung eines beweglichen Objekts
US9074897B2 (en) 2009-06-15 2015-07-07 Qualcomm Incorporated Real-time data with post-processing
US8704707B2 (en) 2010-06-02 2014-04-22 Qualcomm Incorporated Position determination using measurements from past and present epochs
US10386490B2 (en) 2012-07-16 2019-08-20 Microsoft Technology Licensing, Llc Reduced sampling low power GPS
US20140266871A1 (en) * 2013-03-15 2014-09-18 Asc Signal Corporation Method for Satellite Beacon Signal Detection and Antenna Alignment
US10317538B2 (en) 2013-08-27 2019-06-11 Microsoft Technology Licensing, Llc Cloud-offloaded global satellite positioning
CN105474040B (zh) 2013-10-21 2018-08-14 华为技术有限公司 能够确定其速度的无线接收器
US9671499B2 (en) * 2013-10-30 2017-06-06 Microsoft Technology Licensing, Llc High-sensitivity GPS device with directional antenna
KR101603160B1 (ko) 2014-10-29 2016-03-14 씨스존 주식회사 네트워크 연동 기능을 가진 비콘 게이트웨이를 이용하는 비콘 서비스 시스템 및 이를 이용한 비콘 신호 기반의 서비스 제공 방법
KR101694060B1 (ko) 2015-09-17 2017-01-06 강윤정 하나의 비콘 신호 발생장치와 하나의 스마트 단말기를 이용한 위치 추적 방법 및 시스템
WO2017122206A1 (fr) * 2016-01-13 2017-07-20 Hoopo Systems Ltd. Procédé et système de radiolocalisation
IL253488A0 (en) * 2017-07-14 2017-09-28 Zwirn Gil Spatial imaging using wireless networks
CN110146905B (zh) * 2018-02-12 2021-06-29 清华大学 定位信号接收方法和接收机
EP3874292A4 (fr) * 2018-11-01 2022-08-17 Hoopo Systems Ltd. Procédé et système de radiolocalisation dans un transfert de données réduit
CN111650616B (zh) * 2020-05-12 2023-03-24 烟台南山学院 一种高精度北斗导航定位系统导航定位参数计算方法
CN118259317B (zh) * 2024-05-29 2024-07-30 北京航空航天大学 基于小波变换的正则化自编码器序列故障检测方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5663734A (en) * 1995-10-09 1997-09-02 Precision Tracking, Inc. GPS receiver and method for processing GPS signals
WO1999044073A1 (fr) * 1998-02-27 1999-09-02 Ericsson Inc. Procede et systeme mondial autonome de localisation (gps) a haute sensibilite

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5477458A (en) * 1994-01-03 1995-12-19 Trimble Navigation Limited Network for carrier phase differential GPS corrections
US5774829A (en) * 1995-12-12 1998-06-30 Pinterra Corporation Navigation and positioning system and method using uncoordinated beacon signals in conjunction with an absolute positioning system

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5663734A (en) * 1995-10-09 1997-09-02 Precision Tracking, Inc. GPS receiver and method for processing GPS signals
WO1999044073A1 (fr) * 1998-02-27 1999-09-02 Ericsson Inc. Procede et systeme mondial autonome de localisation (gps) a haute sensibilite

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of WO0153848A2 *

Also Published As

Publication number Publication date
WO2001053848A3 (fr) 2002-05-02
KR20020076254A (ko) 2002-10-09
CN1425226A (zh) 2003-06-18
IL150417A0 (en) 2002-12-01
AU2001221092A1 (en) 2001-07-31
EP1257841A4 (fr) 2009-05-13
WO2001053848A2 (fr) 2001-07-26
JP2003520968A (ja) 2003-07-08

Similar Documents

Publication Publication Date Title
US6285316B1 (en) Locating a mobile unit using signals from both mobile beacons and stationary beacons
WO2001053848A2 (fr) Localisation d'une unite mobile au moyen de signaux satellite traites de maniere coherente associes a des signaux de balises stationnaires
EP2329287B1 (fr) Système de référence temporelle
US6922546B1 (en) GPS signal acquisition based on frequency-domain and time-domain processing
US6661371B2 (en) Oscillator frequency correction in GPS signal acquisition
US7463189B2 (en) Satellite-based positioning system improvement
US7579986B2 (en) Method and system for all-in-view coherent GPS signal PRN codes acquisition and navigation solution determination
US8391341B2 (en) Process for sub-microsecond time transfer using weak GPS/GNSS signals
CN101821643B (zh) 全球导航卫星系统的信号捕获方法及接收器
US20050232338A1 (en) Method and apparatus for detecting and processing GPS signals
US6985542B1 (en) Coherent processing of satellite signals to locate a mobile unit
WO2004063763A1 (fr) Procede et dispositif destines a realiser une synchronisation temporelle
JP5302902B2 (ja) Ｇｐｓ信号を捕捉してユーザ受信機の場所を素早く求めるための方法およびシステム
FI109311B (fi) Menetelmä informaatioelementin reunan määrittämiseksi, järjestelmä ja elektroniikkalaite
US6750814B1 (en) Efficient algorithm for processing GPS signals
US20050147191A1 (en) Extended frequency error correction in a wireless communication receiver
US7876738B2 (en) Preventing an incorrect synchronization between a received code-modulated signal and a replica code
EP1319189A2 (fr) Algorithme efficace servant a traiter des signaux du systeme mondial de localisation (gps)

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 20020719

AK Designated contracting states

Kind code of ref document: A2

Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE TR

AX Request for extension of the european patent

Free format text: AL;LT;LV;MK;RO;SI

RIC1 Information provided on ipc code assigned before grant

Free format text: 7H 04B 7/185 A, 7G 01S 5/02 B

A4 Supplementary search report drawn up and despatched

Effective date: 20090415

RIC1 Information provided on ipc code assigned before grant

Ipc: G01S 5/02 20060101AFI20090407BHEP

17Q First examination report despatched

Effective date: 20100426

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20140701

P01 Opt-out of the competence of the unified patent court (upc) registered

Effective date: 20230520