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WO2004057360A2 - Localisation de position au moyen de signaux de radiodiffusion audio numeriques - Google Patents

Localisation de position au moyen de signaux de radiodiffusion audio numeriques Download PDF

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Publication number
WO2004057360A2
WO2004057360A2 PCT/US2003/040729 US0340729W WO2004057360A2 WO 2004057360 A2 WO2004057360 A2 WO 2004057360A2 US 0340729 W US0340729 W US 0340729W WO 2004057360 A2 WO2004057360 A2 WO 2004057360A2
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WO
WIPO (PCT)
Prior art keywords
signal
broadcast signal
user terminal
digital audio
audio broadcast
Prior art date
Application number
PCT/US2003/040729
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English (en)
Other versions
WO2004057360A3 (fr
Inventor
Jimmy K. Omura
James J. Spilker, Jr.
Original Assignee
Rosum Corporation
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
Application filed by Rosum Corporation filed Critical Rosum Corporation
Priority to AU2003299753A priority Critical patent/AU2003299753A1/en
Publication of WO2004057360A2 publication Critical patent/WO2004057360A2/fr
Publication of WO2004057360A3 publication Critical patent/WO2004057360A3/fr

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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
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/38—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
    • G01S19/39—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/42—Determining position
    • G01S19/45—Determining position by combining measurements of signals from the satellite radio beacon positioning system with a supplementary measurement
    • G01S19/46—Determining position by combining measurements of signals from the satellite radio beacon positioning system with a supplementary measurement the supplementary measurement being of a radio-wave signal type
    • 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
    • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
    • G01S5/0257—Hybrid positioning
    • G01S5/0268—Hybrid positioning by deriving positions from different combinations of signals or of estimated positions in a single positioning system
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C21/00—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00
    • G01C21/20—Instruments for performing navigational calculations
    • G01C21/206—Instruments for performing navigational calculations specially adapted for indoor navigation
    • 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
    • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/0009—Transmission of position information to remote stations
    • G01S5/0018—Transmission from mobile station to base station
    • G01S5/0036—Transmission from mobile station to base station of measured values, i.e. measurement on mobile and position calculation on base station
    • 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
    • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/0009—Transmission of position information to remote stations
    • G01S5/0045—Transmission from base station to mobile station
    • G01S5/0054—Transmission from base station to mobile station of actual mobile position, i.e. position calculation on base station
    • 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
    • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/0009—Transmission of position information to remote stations
    • G01S5/0081—Transmission between 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
    • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
    • G01S5/0205—Details
    • G01S5/021—Calibration, monitoring or correction
    • 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
    • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
    • G01S5/14—Determining absolute distances from a plurality of spaced points of known location
    • 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
    • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
    • G01S5/14—Determining absolute distances from a plurality of spaced points of known location
    • G01S5/145—Using a supplementary range measurement, e.g. based on pseudo-range measurements

Definitions

  • the present invention relates generally to position determination, and particularly to position determination using digital television (DTV) signals.
  • DTV digital television
  • GPS is widely used for position location, navigation, survey, and time transfer.
  • the GPS system is based on a constellation of 24 on-orbit satellites in sub-synchronous 12 hour orbits. Each satellite carries a precision clock and transmits a pseudo-noise signal, which can be precisely tracked to determine pseudo-range. By tracking 4 or more satellites, one can determine precise position in three dimensions in real time, world-wide. More details are provided in B.W. Parkinson and J. J. Spilker, Jr., Global Positioning System-Theory and Applications, Volumes I and II, AIAA, Washington, DC. 1996.
  • GPS has revolutionized the technology of navigation and position location.
  • GPS is less effective. Because the GPS signals are transmitted at relatively low power levels (less than 100 watts) and over great distances, the received signal strength is relatively weak (on the order o -160 dBw as received by an omni-directional antenna). Thus the signal is marginally useful or not useful at all in the presence of blockage or inside a building.
  • NTSC Television System Committee
  • the invention features a method, apparatus, and computer-readable media for determining the position of a user terminal. It comprises receiving, at the user terminal, a digital audio broadcast signal; and determining a pseudo- range between the user terminal and a transmitter of the digital audio broadcast signal based on a known component of the digital audio broadcast signal; wherein the position of the user terminal is determined based on the pseudo-range between the user terminal and the transmitter of the digital audio broadcast signal and a location of the transmitter of the digital audio broadcast signal.
  • Particular implementations can include one or more of the following features.
  • Implementations comprise determining the position of the user terminal based on the pseudo-range between the user terminal and the transmitter of the digital audio broadcast signal and a location of the transmitter of the digital audio broadcast signal.
  • the digital audio broadcast signal is selected from the group consisting of a European Telecommunications Standards Institute (ETSI) Digital Audio Broadcast (DAB) signal; and an In-Band On-Channel (IBOC) audio broadcast signal.
  • ETSI European Telecommunications Standards Institute
  • DAB Digital Audio Broadcast
  • IBOC In-Band On-Channel
  • the known component of the digital audio broadcast signal is selected from the group consisting of a synchronization symbol; a null symbol in a synchronization channel; and a phase reference symbol in a synchronization channel;.
  • Implementations comprise receiving, at the user terminal, a broadcast signal; and determining a pseudo-range between the user terminal and a transmitter of the broadcast signal based on a known component of the broadcast signal; wherein the position of the user terminal is determined based on the pseudo-range between the user terminal and the transmitter of the digital audio broadcast signal, the pseudo-range between the user terminal and the transmitter of the broadcast signal, a location of the transmitter of the digital audio broadcast signal, and a location of the transmitter of the broadcast signal.
  • the broadcast signal is selected from the group consisting of a broadcast television signal; a mobile telephone cell site broadcast signal; and a Global Positioning System signal.
  • the broadcast television signal is selected from the group consisting of an American Television Standards Committee (ATSC) digital television signal; a European Telecommunications Standards Institute (ETSI) Digital Video Broadcasting - Terrestrial (DVB-T) signal; a Japanese integrated Services Digital Broadcasting-Terrestrial (ISDB-T) signal; and an analog television signal.
  • the mobile telephone cell site broadcast signal is selected from the group consisting of a Global System for Mobile Communications (GSM) signal; a Code-Division Multiple Access (cdmaOne) signal; a WCDMA signal; a cdma2000 signal; and a EDGE signal.
  • GSM Global System for Mobile Communications
  • cdmaOne Code-Division Multiple Access
  • WCDMA Wideband Code Division Multiple Access
  • cdma2000 Code-Division Multiple Access 2000
  • EDGE EDGE
  • Implementations comprise determining the position of the user terminal based on the pseudo-range between the user terminal and the transmitter of the digital audio broadcast signal, the pseudo-range between the user terminal and the transmitter of the broadcast signal, a location of the transmitter of the digital audio broadcast signal, and a location of the transmitter of the broadcast signal.
  • the invention features a method, apparatus, and computer-readable media for determining the position of a user terminal. It comprises receiving a pseudo-range determined between the user terminal and a transmitter of a digital audio broadcast signal based on a known component in the digital audio broadcast signal; and determining the position of the user terminal based on the pseudo-range determined between the user terminal and the transmitter of the digital audio broadcast signal and a location of the transmitter of the digital audio broadcast signal.
  • the digital audio broadcast signal is selected from the group consisting of a European Telecommunications Standards Institute (ETSI) Digital Audio Broadcast (DAB) signal; and an In-Band On-Channel (IBOC) audio broadcast signal.
  • ETSI European Telecommunications Standards Institute
  • DAB Digital Audio Broadcast
  • IBOC In-Band On-Channel
  • the known component of the digital audio broadcast signal is selected from the group consisting of a synchronization symbol; a null symbol in a synchronization channel; and a phase reference symbol in a synchronization channel;.
  • Implementations comprise receiving a pseudo-range determined between the user terminal and a transmitter of a broadcast signal based on a known component in the broadcast signal; and determining the position of the user terminal based on the pseudo-range determined between the user terminal and the transmitter of the digital audio broadcast signal, the pseudo-range determined between the user terminal and the transmitter of the broadcast signal, a location of the transmitter of the digital audio broadcast signal, and a location of the transmitter of the broadcast signal.
  • the broadcast signal is selected from the group consisting of a broadcast television signal; a mobile telephone cell site broadcast signal; and a Global Positioning System signal.
  • the broadcast television signal is selected from the group consisting of an
  • the mobile telephone cell site broadcast signal is selected from the group consisting of a Global System for Mobile Communications (GSM) signal; a Code-Division Multiple Access (cdmaOne) signal; a WCDMA signal; a cdma2000 signal; and a EDGE signal.
  • GSM Global System for Mobile Communications
  • cdmaOne Code-Division Multiple Access
  • WCDMA Wideband Code Division Multiple Access
  • cdma2000 Code-Division Multiple Access
  • EDGE EDGE
  • Implementations of the invention may be used to position cellular telephones, wireless PDA's (personal digital assistant), pagers, cars, OCDMA (orthogonal code-division multiple access) transmitters and a host of other devices. Implementations of the inventions make use of a DTV signal which has excellent coverage. Implementations of the present invention require no changes to the Digital Broadcast Stations.
  • the DTV signal has a power advantage over GPS of more than 50dB, and substantially superior geometry to that which a satellite system could provide, thereby permitting position location even in the presence of blockage and indoors.
  • the DTV signal has roughly eight times the bandwidth of GPS, thereby minimizing the effects of multipath. Due to the high power and sparse frequency components of the DTV signal used for ranging, the processing requirements are minimal. Implementations of the present invention accommodate far cheaper, lower-speed, and lower-power devices than a GPS technique would require.
  • the DTV signal In contrast to satellite systems such as GPS, the range between the DTV transmitters and the user terminals changes very slowly. Therefore the DTV signal is not significantly affected by Doppler effects. This permits the signal to be integrated for a long period of time, resulting in very efficient signal acquisition.
  • the frequency of the DTV signal is substantially lower that that of conventional cellular telephone systems, and so has better propagation characteristics. For example, the DTV signal experiences greater diffraction than cellular signals, and so is less affected by hills and has a larger horizon. Also, the signal has better propagation characteristics through buildings and automobiles. Further, implementations of the present invention utilize a component of the ISDB-T signal that is continuous and constitutes a large percentage of the power of the ISDB-T signal.
  • FIG. 1 depicts an implementation of the present invention using DTV broadcast signals.
  • FIG. 2 illustrates an operation of an implementation of the present invention using DTV broadcast signals.
  • FIG. 3 depicts the geometry of a position determination using three DTV transmitters.
  • FIG. 4 depicts an implementation of a receiver for use in generating a pseudo-range measurement.
  • FIG. 5 describes a simplified example of a position location calculation for a mobile telephone user terminal using two DTV broadcast signals and knowledge of the cell phone base station.
  • FIG. 6 depicts the effects of a single hill on a circle of constant range for a DTV transmitter that is located at the same altitude as the surrounding land.
  • FIG. 7 depicts an implementation of a monitor unit for DTV broadcast signals.
  • FIG. 8 illustrates one implementation for a software receiver.
  • FIG. 9 shows a typical digital audio broadcast (DAB) transmission frame.
  • FIG. 10 shows the transmitted DAB signal as a sequence of transmission frames.
  • FIG. 11 shows the IBOC signal added to an existing FM signal.
  • FIG. 12 shows the IBOC signal without the analog FM signal.
  • FIG. 13 shows an apparatus for determining the location of a user terminal using digital audio broadcast signals such as the DAB and IBOC signals according to a preferred embodiment.
  • FIG. 14 shows a process for the apparatus of FIG. 13 according to a preferred embodiment.
  • FIG. 15 shows an apparatus for determining the location of a user terminal using one or more digital audio broadcast signals such as the DAB and IBOC signals, and one or more broadcast television signals, according to a preferred embodiment.
  • FIG. 16 shows a process for the apparatus of FIG. 15 according to a preferred embodiment.
  • DTV Digital television
  • the European DTV standard called Digital Video Broadcasting (DVB) is the most widely accepted in the world.
  • the DVB terrestrial standard version is denoted DVB-T.
  • the Japanese system is a variation of DVB.
  • the Japan Broadcasting Corp. (NHK) has defined a terrestrial DTV signal for Japan, referred to as the Integrated Services Digital Broadcasting - Terrestrial (ISDB-T) signal.
  • the inventors have recognized that the DTV signals can be used for position location, and have developed techniques for doing so. These techniques are usable in the vicinity of DTV transmitters with a range from the transmitter much wider than the typical TV reception range. Because of the high power of the DTV signals, these techniques can even be used indoors by handheld receivers, and thus provide a possible solution to the position location needs of the Enhanced 911 (E911) system.
  • E911 Enhanced 911
  • the DTV signals are received from transmitters only a few miles distant, and the transmitters broadcast signals at effective radiated powers of up to several hundred kilowatts.
  • the DTV transmitter antennas have significant antenna gain, on the order of 14 dB. Thus there is often sufficient power to permit DTV signal reception inside buildings.
  • the use of the DTV signal is advantageous for several reasons. First, it permits position determination indoors, and at great distances from DTV transmitters. Conventional DTV receivers utilize only one data signal at a time, and so are limited in range from the DTV transmitter by the energy of a single signal.
  • implementations of the present invention utilize the energy of multiple scattered pilot signals simultaneously, thereby permitting operation at greater range from DTV transmitters than conventional DTV receivers.
  • the scattered pilots are not modulated by data. This is advantageous for two reasons. First, all of the power in the scattered pilots is available for position determination; none of the power is devoted to data. Second, the scattered pilots can be observed for long periods of time without suffering the degradation that data modulation would produce. Thus the ability to track signals indoors at substantial range from the DTV tower is greatly expanded. Furthermore, through the use of digital signal processing it is possible to implement these new tracking techniques in a single semiconductor chip.
  • the techniques disclosed herein can be applied to other DTV signals that include known sequences of data by simply modifying the correlator to accommodate the known sequence of data, as would be apparent to one skilled in the relevant arts. These techniques can also be applied to a range of other orthogonal frequency-division multiplexing (OFDM) signals such as satellite radio signals and digital audio broadcast signals, as described in detail below.
  • OFDM orthogonal frequency-division multiplexing
  • Television signals include components that can be used to convey timing information. Suitable components within the American Television Standards Committee (ATSC) digital television signal include synchronization codes such as the Field
  • NSC Television System Committee
  • PAL Phase Alternating Line
  • SECAM Sequential Color with Memory
  • an example implementation 100 includes a user terminal 102 that communicates over an air link with a base station 104.
  • user terminal 102 is a wireless telephone and base station 104 is a wireless telephone base station.
  • base station 104 is part of a mobile MAN (metropolitan area network) or WAN (wide area network).
  • FIG. 1 is used to illustrate various aspects of the invention but the invention is not limited to this implementation.
  • the phrase "user terminal” is meant to refer to any object capable of implementing the DTV position location described. Examples of user terminals include PDAs, mobile phones, cars and other vehicles, and any object which could include a chip or software implementing DTV position location. It is not intended to be limited to objects which are "terminals" or which are operated by "users.”
  • FIG. 2 illustrates an operation of implementation 100.
  • User terminal 102 receives DTV signals from a plurality of DTV transmitters 106 A and 106B through 106N (step 202).
  • Various methods can be used to select which DTV channels to use in position location.
  • a DTV location server 110 tells user terminal 102 of the best DTV channels to monitor.
  • user terminal 102 exchanges messages with DTV location server 110 by way of base station 104.
  • user terminal 102 selects DTV channels to monitor based on the identity of base station 104 and a stored table correlating base stations and DTV channels.
  • user terminal 102 can accept a location input from the user that gives a general indication of the area, such as the name of the nearest city; and uses this information to select DTV channels for processing.
  • user terminal 102 scans available DTV channels to assemble a fingerprint of the location based on power levels of the available DTV channels.
  • User terminal 102 compares this fingerprint to a stored table that matches known fingerprints with known locations to select DTV channels for processing. This selection is based on the power levels of the DTV channels, as well as the directions from which each of the signals are arriving, so as to minimize the dilution of precision (DOP) for the position calculation.
  • DOP dilution of precision
  • User terminal 102 determines a pseudo-range between the user terminal 102 and each DTV transmitter 106 (step 204). Each pseudo-range represents the time difference (or equivalent distance) between a time of transmission from a transmitter 106 of a component of the DTV broadcast signal and a time of reception at the user terminal 102 of the component, as well as a clock offset at the user terminal. [0049] User terminal 102 transmits the pseudo-ranges to DTV location server 110.
  • DTV location server 110 is implemented as a general-purpose computer executing software designed to perform the operations described herein.
  • DTV location server is implemented as an ASIC (application- specific integrated circuit).
  • DTV location server 110 is implemented within or near base station 104.
  • the DTV signals are also received by a plurality of monitor units 108A through 108N.
  • Each monitor unit can be implemented as a small unit including a transceiver and processor, and can be mounted in a convenient location such as a utility pole, DTV transmitters 106, or base stations 104. In one implementation, monitor units are implemented on satellites.
  • Each monitor unit 108 measures, for each of the DTV transmitters 106 from which it receives DTV signals, a time offset between the local clock of that DTV transmitter and a reference clock.
  • the reference clock is derived from GPS signals. The use of a reference clock permits the determination of the time offset for each DTV transmitter 106 when multiple monitor units 108 are used, since each monitor unit 108 can determine the time offset with respect to the reference clock. Thus, offsets in the local clocks of the monitor units 108 do not affect these determinations.
  • no external time reference is needed.
  • a single monitor unit receives DTV signals from all of the same DTV transmitters as does user terminal 102. In effect, the local clock of the single monitor unit functions as the time reference.
  • each time offset is modeled as a fixed offset. In another implementation each time offset is modeled as a second order polynomial fit of the form
  • Offset a + b(t -T) + c(t -Tf (1)
  • each measured time offset is transmitted periodically to the DTV location server using the Internet, a secured modem connection, as part of the actual DTV broadcast data, or the like.
  • the location of each monitor unit 108 is determined using GPS receivers.
  • DTV location server 110 receives information describing the phase center (i.e., the location) of each DTV transmitter 106 from a database 112.
  • the phase center of each DTV transmitter 106 is measured by using monitor units 108 at different locations to measure the phase center directly.
  • One approach to doing this is to use multiple time-synchronized monitor units at known locations.
  • DTV location server 110 receives weather information describing the air temperature, atmospheric pressure, and humidity in the vicinity of user terminal 102 from a weather server 114. The weather information is available from the Internet and other sources. DTV location server 110 determines tropospheric propagation velocity from the weather information using techniques such as those disclosed in B. Parkinson and J. Spilker, Jr.
  • DTV location server 110 can also receive from base station 104 information which identifies a general geographic location of user terminal 102. For example, the information can identify a cell or cell sector within which a cellular telephone is located. This information is used for ambiguity resolution, as described below. [0057] DTV location server 110 determines a position of the user terminal based on the pseudo-ranges and a location and clock offset of each of the transmitters (step 206). FIG. 3 depicts the geometry of a position determination using three DTV transmitters 106.
  • DTV transmitter 106A is located at position (xl, yl). The range between user terminal 102 and DTV transmitter 106A is rl.
  • DTV 106B transmitter is located at position (x2, v2). The range between user terminal 102 and DTV transmitter 106B is r2.
  • DTV transmitter 106N is located at position (x3, y3). The range between user terminal 102 and DTV transmitter 106N is r3.
  • DTV location server 110 may adjust the value of each pseudo-range according to the tropospheric propagation velocity and the time offset for the corresponding DTV transmitter 106.
  • DTV location server 110 uses the phase center information from database 112 to determine the position of each DTV transmitter 106.
  • User terminal 102 makes three or more pseudo-range measurements to solve for three unknowns, namely the position (x, y) and clock offset T of user terminal 102.
  • the techniques disclosed herein are used to determine position in three dimensions such as longitude, latitude, and altitude, and can include factors such as the altitude of the DTV transmitters .
  • the three pseudo-range measurements prl, pr2 and pr3 are given by
  • prl rl +T (2a)
  • pr2 r2 +T (3a)
  • X represents the two-dimensional vector position (x, y) of user terminal
  • XI represents the two-dimensional vector position (xl, yl) of DTV transmitter 106A
  • X2 represents the two-dimensional vector position (x2, y2) of DTV transmitter 106B
  • X3 represents the two-dimensional vector position (x3, y3) of DTV transmitter 106N.
  • the clock offset can be considered to be a function of time, T(t).
  • T(t) For a small time interval, ⁇ , the clock offset, T(t), can be modeled by a constant and a first order term. Namely, [0062]
  • T(t+ A) T(t)+— A dt (8)
  • the pseudo-range measurements may be described as: [0066]
  • the user terminal 102 commences with an additional set of pseudo-range measurements at some time ⁇ after the initial set of measurements.
  • pr2(t2+A) r2 +T(t2)+— A (3c) dt
  • the user terminal 102 projects all the pseudo-range measurements to some common point in time so that the effect of the first order term is effectively eliminated. For example, consider if some common reference time tO is used. Applying equations (2b-4b) and (2c-4c) it is straightforward to show that we can project the measurements to a common instant of time as follows:
  • prl(tO) prl(tl)+ fprl(tl+A) -prl(tl)](tO-tl)/A (2d)
  • pr2(t0) pr2(t2)+ fpr2(t2+A) -pr2(t2)](W-t2)/A (3d) [0086]
  • a separate tracking loop can be dedicated to each DTV transmitter 106. These tracking loops effectively interpolate between pseudo-range measurements. The state of each of these tracking loops is sampled at the same instant of time.
  • user terminal 102 does not compute pseudo- ranges, but rather takes measurements of the DTV signals that are sufficient to compute pseudo-range, such as a segment of the correlator output, and transmits these measurements to DTV location server 110. DTV location server 110 then computes the pseudo-ranges based on the measurements, and computes the position based on the pseudo-ranges, as described above.
  • the position of user terminal 102 is computed by user terminal 102.
  • all of the necessary information is transmitted to user terminal 102.
  • This information can be transmitted to user terminal by DTV location server 110, base station 104, one or more DTV transmitters 106, or any combination thereof.
  • User terminal 102 measures the pseudo-ranges and solves the simultaneous equations as described above. This implementation is now described.
  • User terminal 102 receives the time offset between the local clock of each
  • User terminal 102 also receives information describing the phase center of each DTV transmitter 106 from a database 112. [0094] User terminal 102 receives the tropospheric propagation velocity computed by DTV locations server 110. In another implementation, user terminal 102 receives weather information describing the air temperature, atmospheric pressure, and humidity in the vicinity of user terminal 102 from a weather server 114, and determines tropospheric propagation velocity from the weather information using conventional techniques. [0095] User terminal 102 can also receive from base station 104 information which identifies the rough location of user terminal 102. For example, the information can identify a cell or cell sector within which a cellular telephone is located. This information is used for ambiguity resolution, as described below.
  • User terminal 102 receives DTV signals from a plurality of DTV transmitters 106 and determines a pseudo-range between the user terminal 102 and each DTV transmitter 106. User terminal 102 then determines its position based on the pseudo- ranges and the phase centers of the transmitters.
  • the position of user terminal 102 can be determined using the two DTV transmitters and the offset T computed during a previous position determination.
  • the values of T can be stored or maintained according to conventional methods. This assumes, of course, that the local clock is stable enough over the period of time since T was computed.
  • base station 104 determines the clock offset of user terminal 102. In this implementation, only two DTV transmitters are required for position determination. Base station 104 transmits the clock offset Tto DTV location server 110, which then determines the position of user terminal 102 from the pseudo-range computed for each of the DTV transmitters.
  • FIG. 4 depicts an implementation 400 of a receiver for use in generating a pseudo-range measurement.
  • receiver 400 is implemented within user terminal 102.
  • receiver 400 is implemented within a monitor unit 108.
  • tuner 406 also downconverts the received DTV signal(s) to intermediate frequency (IF).
  • IF intermediate frequency
  • Mixers 4081 and 408Q combine the carrier signal produced by carrier generator 418 with the tuned DTV signal to produce in-phase and quadrature DTV signals at intermediate frequency (IF) or baseband.
  • clock 416 runs at 27 MHz.
  • Each of these signals is filtered by one of filters 4101 and 410Q, and digitized by one of analog-to-digital converters (A/D) 4111 and 411Q, to produce signals m[t - 7] and q[t - T ⁇ , respectively.
  • A/D converter with a switch is used to alternately sample the in-phase and quadrature channels.
  • a correlator 4121 combines signal m[t - T with a synchronization signal s[t - T*], and provides the correlation output to a search controller 414.
  • a delay-lock loop 422 comprises a correlator 412Q, a filter 424, a number- controlled oscillator (NCO) 426 clocked by clock 416, and a synchronization generator 428 that generates a digital representation of the scattered pilot signals.
  • Correlator 412Q combines signal q[t - T ⁇ with synchronization signal signals s[t - T*], and provides the correlation output, after filtering by filter 424, to NCO 426.
  • NCO 426 drives synchronization generator 428 according to search controller 414.
  • Control is provided by search controller 414 during signal acquisition, and by NCO 426 during signal tracking after acquisition. A pseudo-range is obtained by sampling NCO 426.
  • the position location operation at the subscriber handset or other device need only take place when the subscriber needs position location. For a subscriber walking slowly, in a slowly moving vehicle, or sitting in a building or field in an emergency, this location information need only be measured infrequently. Thus the battery or other power source can be very small.
  • receiver 400 can be implemented using the concepts described above, for example by processing the received DTV signal using fast Fourier transform (FFT) methods.
  • FFT fast Fourier transform
  • Important to achieving this performance is the concept of correlating with all scattered pilots in parallel, or at least with the 9 in a single segment. Wider bandwidths of the composite signal provide greater position location accuracy. The timing accuracy is inversely proportional to the bandwidth.
  • FIG. 5 describes a simplified example of a position location calculation for a mobile telephone user terminal 102 receiving DTV signals from two separate DTV antennas 106 A and 106B.
  • FIG. 5 describes a simplified example of a position location calculation for a mobile telephone user terminal 102 receiving DTV signals from two separate DTV antennas 106 A and 106B.
  • the user's clock offset is already known.
  • circles of constant range 502A and 502B are drawn about each of transmit antennas 106A and 106B, respectively.
  • the position for a user terminal, including correction for the user terminal clock offset is then at one of the intersections 504A and 504B of the two circles 502A and 502B.
  • the ambiguity is resolved by noting that base station 104 can determine in which sector 508 of its footprint (that is, its coverage area) 506 the user terminal is located. Of course if there are more than two DTV transmitters in view, the ambiguity can be resolved by taking the intersection of three circles. Since the synchronization codes from TV transmitters are repetitive in nature, a cycle ambiguity exists, determined by the repetition period of the TV synch code, which results in a distance ambiguity equal to the repetition period times by the speed of light. This cycle ambiguity may be resolved by the same technique described for the simplified example of FIG. 5 as long as the distance ambiguity is large in comparison with the size of the cell site, which is typically the case.
  • user terminal 102 can accept an input from a user that gives a general indication of the area, such as the name of the nearest city.
  • user terminal 102 scans available DTV channels to assemble a fingerprint of the location describing the set of visible channels. User terminal 102 compares this fingerprint to a stored table that matches known fingerprints with known locations to identify the current rough location of user terminal 102.
  • the position location calculation includes the effects of ground elevation.
  • the circles of constant range are distorted.
  • FIG. 6 depicts the effects of a single hill 604 on a circle of constant range 602 for a DT transmitter 106 that is located at the same altitude as the surrounding land.
  • FIG. 7 depicts an implementation 700 of monitor unit 108.
  • An antenna 704 receives GPS signals 702.
  • a GPS time transfer unit 706 develops a master clock signal based on the GPS signals.
  • a NCO (numerically controlled oscillator) code synchronization timer 708A develops a master synchronization signal based on the master clock signal.
  • the channel synchronization signal can include the ATSC standard Segment Synchronization Bits or the Field Synchronization Segments. Alternatively it can include the DVB-T or ISDB-T scattered pilot carriers.
  • the NCO synchronization timers 708A in all of the monitor units 108 are synchronized to a base date and time.
  • a DTV antenna 712 receives a plurality of DIN signals 710. In another implementation, multiple DTV antennas are used.
  • An amplifier 714 amplifies the DTV signals.
  • One or more DTV tuners 716A through 716 ⁇ each tunes to a DTV channel in the received DTV signals to produce a DTV channel signal.
  • Each of a plurality of NCO code synchronization timers 708B through 708M receives one of the DTV channel signals.
  • Each of NCO code synchronization timers 708B through 708M extracts a channel synchronization signal from a DTV channel signal.
  • the channel synchronization signal can include the ATSC standard Segment Synchronization Bits or the Field
  • Synchronization Segments can include the DVB-T and ISDB-T scattered pilot carriers.
  • the continuous pilot signals and symbol timing within the DVB-T or ISDB-T signal are used as acquisition aids.
  • Each of a plurality of summers 718 A through 718N generates a clock offset between the master synchronization signal and one of the channel synchronization signals.
  • Processor 720 formats and sends the resulting data to DTV location server 110.
  • this data includes, for each DTV channel measured, the identification number of the DTV transmitter, the DTV channel number, the antenna phase center for the DTV transmitter, and the clock offset. This data can be fransmitted by any of a number of methods including air link and the Internet.
  • the data is broadcast in spare MPEG packets on the DTV channel itself.
  • the clock offsets for each channel may also be modeled as a function of time.
  • FIG. 8 illustrates one implementation 800 for a software receiver.
  • Antenna 802 receives a DIN signal.
  • Antenna 802 can be a magnetic dipole or any other type of antenna capable of receiving DTV signals.
  • a bandpass filter 804 passes the entire DTV signal spectrum to an LNA 806.
  • filter 804 is a tunable bandpass filter that passes the spectrum for a particular DTV channel under the control of a digital signal processor (DSP) 814.
  • DSP digital signal processor
  • a low-noise amplifier (LNA) 806 amplifies and passes the selected signal to a DTV channel selector 808.
  • DTV channel selector 808 selects a particular DTV channel under the control of a processor 814, and filters and downconverts the selected channel signal from UHF (ultra-high frequency) to IF (intermediate frequency) according to conventional methods.
  • An amplifier (AMP) 810 amplifies the selected IF channel signal.
  • This amplifier may employ automatic gain control (AGC) in order to improve the dynamic range of the architecture.
  • An analog-to-digital converter and sampler (A/D) 812 produces digital samples of the DTV channel signal s (t) and passes these samples to
  • R st0r e(v) Upon exit from the process, R st0r e(v) will store the correlation between the incident sampled signal s samp (t) and the complex code signal s co d e (t). R st0 rJX) may be further refined by searching over smaller steps of ⁇ . The initial step size for ⁇ must be less then half the Nyquist rate — . The time offset rthat produces the maximum
  • correlation output is used as the pseudo-range.
  • Any digital broadcast signal comprises known signal components that allow a receiver to synchronize to the parameters of the transmitted signal. Typically this allows a receiver to estimate frequency and time parameters of the fransmitted signal where encoded (error correction coding and interleaving) data packets are transmitted in some frame structure.
  • Such known signal components of the broadcast signal can be used to create a reference waveform at the receiver. This reference waveform can be used to compute a pseudo range between the receiver and the broadcast station by cross correlation of this reference waveform with the received broadcast signal. All of the signals described above, including analog TV signals, have fixed known elements in their transmitted signals that can be used to create reference waveforms.
  • any such reference waveform can be used at user terminal 102 to cross correlate with a corresponding received signal to compute a pseudo range between the location of user terminal 102 and the transmitter location.
  • digital audio broadcast signals which have such known signal components are used to create a reference waveform allowing the computing of pseudo ranges for position location systems according to embodiments of the present invention.
  • the pseudoranges obtained from digital audio broadcast signals can be used alone or in conjunction with pseudoranges obtained from other signals, such as the broadcast television signals described above, to determine the position of user terminal 102.
  • OFDM Orthogonal Frequency Division Multiplexing
  • An OFDM signal consists of a sum of subcarriers that are modulated by using Phase Shift Keying (PSK) or Quadrature Amplitude Modulation (QAM).
  • PSK Phase Shift Keying
  • QAM Quadrature Amplitude Modulation
  • the modulation interval of each of these subcarriers is typically much longer than the symbol time for a conventional single carrier signal of the same total bandwidth. This modulation interval for each subcarrier is called the symbol time for the OFDM signal.
  • the symbol time for an OFDM signal is approximately N times the symbol time of a single carrier signal of the same bandwidth where N is the number of subcarriers in the OFDM signal.
  • This long symbol time is the key advantage of OFDM against multipath.
  • the number of carriers which determine the symbol time interval, for a given total signal bandwidth, are selected so that the broadcast channel multipath delays are some fraction of this symbol time interval.
  • Longer symbol times place a more stringent frequency stability requirement on OFDM systems compared to a single carrier system such as the ATSC digital television standard for the United States.
  • TU useful symbol time
  • guard time there is an additional guard time
  • TS TU + TG.
  • the useful symbol time, TU is also the sample duration for the DFT computation for each symbol in the receivers for these OFDM signals.
  • the guard time TG is chosen to be larger than the expected delay spread. The guard time could consist of no signal at all. However, then the carriers would no longer be orthogonal over any delayed TU interval.
  • the OFDM signal is cyclically extended in the guard time. This insures that even if the DFT interval (useful symbol time TU) is delayed, there is an even number of cycles within the DFT interval, assuming this delay is less than the guard time.
  • a conventional timing and frequency synchronization technique is described in R. Van Nee and R. Prasad, "OFDM For Wireless Multimedia Communications," Artech House Publishers, 2000.
  • DAB Digital Audio Broadcasting
  • ETSI European Telecommunications Standards Institute
  • DAB was the first standard to use OFDM.
  • OFDM European Telecommunications Standards Institute
  • One important reason to use OFDM for DAB is the possibility to use a single frequency network, which greatly enhances spectrum efficiency.
  • two or more transmitters may be sending the same signal, with different delays, to a receiver.
  • receivers can more easily handle this "apparent multipath" created by these fransmitters.
  • the Main Service Channel is used to carry audio and data service components consisting of Common Interleaved Frames (CIFs).
  • CIFs Common Interleaved Frames
  • FIC Fast Information Channel
  • FIBs Fast Information Blocks
  • the Synchronization Channel is used for aiding the receivers' basic demodulator functions, such as transmission frame synchronization, automatic frequency confrol, channel state estimation, and transmitter identification.
  • FIG. 9 shows a typical DAB fransmission frame.
  • Orthogonal Frequency Division Multiplex (OFDM) symbols are generated from the output of a multiplexer which combines CIFs and FIBs in a frequency interleaved symbol generator before being combined with a synchronization channel symbol generator at the OFDM signal generator.
  • OFDM Orthogonal Frequency Division Multiplex
  • Each fransmission frame consists of consecutive OFDM symbols.
  • the number of OFDM symbols in a transmission frame is dependent on the transmission mode.
  • the synchronization channel in any fransmission mode occupies the first two
  • the first OFDM symbol of the fransmission frame is the Null symbol of duration T N L -
  • the remaining part of the transmission frame are OFDM symbols of duration T s .
  • These OFDM symbols are modulated carriers with spacing equal to 1/Tu.
  • T s T v + ⁇ where ⁇ is a guard interval.
  • L is the number of
  • T F is the transmission frame duration.
  • T NU L is the Null symbol duration (Null symbol not included in L).
  • Ts is the duration of OFDM symbols (Null symbol is different).
  • Tu is the inverse carrier spacing.
  • ⁇ is the duration of the time interval called guard interval.
  • the second OFDM symbol of the transmission frame is the phase reference symbol which sets the phase reference at the receivers for the following symbols.
  • This phase reference symbol has duration of Ts seconds.
  • all the K carriers are modulated using differentially encoded Quadrature Phase Shift Keying (D-QPSK) modulation.
  • the demodulator for this modulation uses the previous symbol as a reference for demodulation of the current symbol.
  • the known phases used to modulate each of the K D-QPSK modulated carriers are fixed for each of the four fransmission modes.
  • the phase reference symbol consisting of K D-QPSK modulated carriers is a known signal component that is used by embodiments of the present invention to compute a pseudorange to the tower transmitting the DAB signal.
  • FIG. 10 shows the transmitted DAB signal as a sequence of fransmission frames where there is a null symbol (no signal) followed by the known Phase Reference Symbol (PRS) which is then followed by the remaining K-l symbols of the transmission frame.
  • PRS Phase Reference Symbol
  • the normal symbols consist of K carriers modulated by D-QPSK.
  • Embodiments of the present invention preferably use as the reference waveform the Phase Reference Symbol (PRS) of duration Ts seconds located right after the first null symbol in each transmission frame. These frames occur every T F seconds.
  • PRS Phase Reference Symbol
  • the IBOC system is based on the fact that digital systems are more immune to interference than analog systems. Therefore it is easier for a digital receiver to reject the interference from an analog signal than for an analog receiver to reject a digital signal's interference. Coexistence is achieved in the IBOC system by broadcasting the digital signal at a much lower power level than the analog signal. Because of the broadcast efficiency of IBOC, a low-power signal can maintain existing coverage areas for digital receivers while allowing analog receivers to reject the interfering digital IBOC signal.
  • the United States IBOC standard is based on OFDM signals. Because these IBOC signals must coexist in the same band as the analog broadcast signal, however, the distribution of the OFDM subcarriers is different from DAB.
  • 10 subcarriers are located in the lower sideband and 10 subcarriers are in the upper sideband as illustrated in FIG. 11.
  • the IBOC signal is 25 dB below the analog FM signal. Because the digital signal power is lower, it can thus efficiently use the entire frequency mask area. Eventually when the analog FM signal is turned off, a fully digital waveform can be used as illustrated in FIG. 12. [0154] Although the bandwidths are different, the basic structure of IBOC for AM broadcast is similar. The higher bandwidth of FM channels allows high data rates for the IBOC digital signals. IBOC data rates of 256 Kbps with coexisting FM signals are possible while with the coexisting AM signals the data rates are between 96 Kbps and 128 Kbps. The IBOC method is highly attractive because it fits within much of the existing regulatory statutes and commercial interests.
  • the United States IBOC system is limited to the more narrow bandwidths of existing FM and AM broadcast channels with less than full power while it shares these channels with existing analog broadcast signals.
  • the FM signals are less than 400 KHz while the AM signals are even more narrow in bandwidth.
  • FIG. 13 shows an apparatus 1300 for determining the location of user terminal 102 using digital audio broadcast signals such as the DAB and IBOC signals according to a preferred embodiment.
  • FIG. 14 shows a process 1400 for apparatus 1300 according to a preferred embodiment.
  • Each receiver 1306A through 1306N receives a different digital audio broadcast signal from respective antennas 1302 A through 1302N in accordance with tuners 1304 A through 1304N (step 1402). Another implementation is to use a single antenna and receiver system and tune to different digital audio broadcast signals in a time sequence. Here the apparatus for determining the location of user terminal 102 would sequentially compute the pseudo ranges of the different digital audio broadcast signals. [0158] Each pseudorange unit 1308A through 1308N determines a pseudorange between user terminal 102 and a fransmitter of the respective digital audio broadcast signal based on a known component of the respective digital audio broadcast signal (step 1404), as described above.
  • Embodiments of the present invention employ one or more digital audio broadcast signals and one or more other broadcast signals.
  • These other broadcast signals can include broadcast television signals, mobile telephone cell site broadcast signals, and Global Positioning System signals.
  • the broadcast television signals can include American Television Standards Committee (ATSC) digital television signals, European Telecommunications Standards Institute (ETSI) Digital Video Broadcasting - Terrestrial (DVB-T) signals, Japanese Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) signals, and analog television signals.
  • ATSC American Television Standards Committee
  • ETSI European Telecommunications Standards Institute
  • DVD-T Digital Video Broadcasting - Terrestrial
  • ISDB-T Japanese Integrated Services Digital Broadcasting-Terrestrial
  • the mobile telephone signals can include the second generation (2G) mobile phone systems such as the Global System for Mobile Communications (GSM) signals and Code-Division Multiple Access (cdmaOne) signals and the third generation (3G) mobile phone systems such as WCDMA, cdma2000, and EDGE. Position location using mobile telephone signals is described in U.S. Non-provisional Patent Application Serial No.
  • 2G second generation mobile phone systems
  • GSM Global System for Mobile Communications
  • cdmaOne Code-Division Multiple Access
  • 3G Third generation
  • FIG. 15 shows an apparatus 1500 for determining the location of user terminal 102 using one or more digital audio broadcast signals such as the DAB and IBOC signals, and one or more other broadcast signals, according to a preferred embodiment.
  • FIG. 16 shows a process 1600 for apparatus 1500 according to a preferred embodiment.
  • Each receiver 1506A through 1506N receives a different digital audio broadcast signal from respective antennas 1502A through 1502N in accordance with tuners 1504A through 1504N (step 1602).
  • Each pseudorange unit 1508A through 1508N determines a pseudorange between user terminal 102 and a transmitter of the respective digital audio broadcast signal based on a known component of the respective digital audio broadcast signal (step 1604), as described above.
  • Each receiver 1516A through 1516N receives a different broadcast signal from respective antennas 1512A through 1512N in accordance with tuners 1514A through 1514N (step 1606).
  • Each pseudorange unit 1518 A through 1518N determines a pseudorange between user terminal 102 and a transmitter of the respective broadcast signal based on a known component of the respective broadcast signal (step 1608), as described above.
  • Processor 1510 determines a position of user terminal 102 based on the pseudoranges (step 1610), as described above.
  • Another embodiment of the inventions combines the digital audio broadcasting and DTV ranging signals described above with other forms of signals from which a pseudo-range can be computed. Additionally, the digital audio broadcasting signals can be combined with cellular base-station signals or digital radio signals, or any other signal that includes a synchronization code, for a combined position solution. [0169] Alternate Embodiments .
  • the invention can be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or in combinations thereof.
  • Apparatus of the invention can be implemented in a computer program product tangibly embodied in a machine-readable storage device for execution by a programmable processor; and method steps of the invention can be performed by a programmable processor executing a program of instructions to perform functions of the invention by operating on input data and generating output.
  • the invention can be implemented advantageously in one or more computer programs that are executable on a programmable system including at least one programmable processor coupled to receive data and instructions from, and to transmit data and instructions to, a data storage system, at least one input device, and at least one output device.
  • Each computer program can be implemented in a high-level procedural or object-oriented programming language, or in assembly or machine language if desired; and in any case, the language can be a compiled or interpreted language.
  • Suitable processors include, by way of example, both general and special purpose microprocessors.
  • a processor will receive instructions and data from a read- only memory and/or a random access memory.
  • a computer will include one or more mass storage devices for storing data files; such devices include magnetic disks, such as internal hard disks and removable disks; magneto-optical disks; and optical disks.
  • Storage devices suitable for tangibly embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, such as EPROM, EEPROM, and flash memory devices; magnetic disks such as internal hard disks and removable disks; magneto-optical disks; and CD-ROM disks. Any of the foregoing can be supplemented by, or incorporated in, ASICs (application-specific integrated circuits).
  • ASICs application-specific integrated circuits
  • Implementations of the present invention exploit the fact that the DTV signal has high power, and can still be tracked by capturing bursts of signal or using a low-duty- factor reference signal which does not use all of the incident signal energy.
  • DLL time-gated delay-lock loop
  • implementations employ other variations of the DLL, including coherent, non-coherent, and quasi-coherent DLLs, such as those disclosed in J. J. Spilker, Jr., Digital Communications by Satellite, Prentice-Hall, Englewood Cliffs NJ, 1977, Chapter 18 and B.
  • DTV location server 110 employs redundant signals available at the system level, such as pseudo-ranges available from the DTV transmitters, making additional checks to validate each DTV channel and pseudo-range, and to identify pseudo-ranges of DTV channels that are erroneous.
  • RAIM receiver autonomous integrity monitoring

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  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Automation & Control Theory (AREA)
  • Circuits Of Receivers In General (AREA)
  • Two-Way Televisions, Distribution Of Moving Picture Or The Like (AREA)
  • Synchronisation In Digital Transmission Systems (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

L'invention concerne un procédé, un appareil, et un support lisible par un ordinateur permettant de déterminer la position d'un terminal utilisateur. Le procédé de l'invention consiste: à recevoir, au niveau du terminal utilisateur, un signal de radiodiffusion audio numérique; et à déterminer une pseudo-distance entre le terminal utilisateur et un émetteur du signal de radiodiffusion audio numérique en fonction d'une composante connue de ce dernier, la position du terminal utilisateur étant déterminée en fonction de la pseudo-distance entre le terminal utilisateur et l'émetteur du signal de radiodiffusion audio numérique et l'emplacement de l'émetteur du signal de radiodiffusion audio numérique.
PCT/US2003/040729 2002-12-18 2003-12-18 Localisation de position au moyen de signaux de radiodiffusion audio numeriques WO2004057360A2 (fr)

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Cited By (7)

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GB2423431A (en) * 2005-01-31 2006-08-23 Furuno Electric Co Receiver for receiving marine-related information transmitted by a radio communications system
WO2008016901A2 (fr) * 2006-08-01 2008-02-07 Qualcomm Incorporated Système et/ou procédé pour fournir des mises à jour d'informations à un serveur de localisation
EP2119259A1 (fr) * 2006-12-27 2009-11-18 TruePosition, Inc. Localisation sans abonnement de dispositifs sans fil
RU2392775C2 (ru) * 2005-07-25 2010-06-20 Квэлкомм Инкорпорейтед Способ и устройство для поддержки отпечатка беспроводной сети
US8477731B2 (en) 2005-07-25 2013-07-02 Qualcomm Incorporated Method and apparatus for locating a wireless local area network in a wide area network
US8483704B2 (en) 2005-07-25 2013-07-09 Qualcomm Incorporated Method and apparatus for maintaining a fingerprint for a wireless network
US11729039B2 (en) 2020-08-31 2023-08-15 Sinclair Broadcast Group, Inc. ATSC 3.0 single frequency networks used for positioning navigation timing and synergy 4G / 5G networks

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US5271034A (en) * 1991-08-26 1993-12-14 Avion Systems, Inc. System and method for receiving and decoding global positioning satellite signals
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

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2423431B (en) * 2005-01-31 2008-08-20 Furuno Electric Co Receiver
GB2423431A (en) * 2005-01-31 2006-08-23 Furuno Electric Co Receiver for receiving marine-related information transmitted by a radio communications system
US7561969B2 (en) 2005-01-31 2009-07-14 Furuno Electric Company Limited Navtex receiver
RU2439852C1 (ru) * 2005-07-25 2012-01-10 Квэлкомм Инкорпорейтед Способ и устройство для поддержки отпечатка беспроводной сети
US8477731B2 (en) 2005-07-25 2013-07-02 Qualcomm Incorporated Method and apparatus for locating a wireless local area network in a wide area network
US9060380B2 (en) 2005-07-25 2015-06-16 Qualcomm Incorporated Method and apparatus for locating a wireless local area network in a wide area network
RU2392775C2 (ru) * 2005-07-25 2010-06-20 Квэлкомм Инкорпорейтед Способ и устройство для поддержки отпечатка беспроводной сети
US8798008B2 (en) 2005-07-25 2014-08-05 Qualcomm Incorporated Method and apparatus for locating a wireless local area network in a wide area network
US8483704B2 (en) 2005-07-25 2013-07-09 Qualcomm Incorporated Method and apparatus for maintaining a fingerprint for a wireless network
US8971797B2 (en) 2006-08-01 2015-03-03 Qualcomm Incorporated System and/or method for providing information updates to a location server
KR101217939B1 (ko) * 2006-08-01 2013-01-02 퀄컴 인코포레이티드 로케이션 서버에 정보 업데이트를 제공하는 시스템 및/또는방법
WO2008016901A2 (fr) * 2006-08-01 2008-02-07 Qualcomm Incorporated Système et/ou procédé pour fournir des mises à jour d'informations à un serveur de localisation
WO2008016901A3 (fr) * 2006-08-01 2008-07-10 Qualcomm Inc Système et/ou procédé pour fournir des mises à jour d'informations à un serveur de localisation
US9554354B2 (en) 2006-08-01 2017-01-24 Qualcomm Incorporated System and/or method for providing information updates to a location server
EP2119259A4 (fr) * 2006-12-27 2011-07-27 Trueposition Inc Localisation sans abonnement de dispositifs sans fil
EP2119259A1 (fr) * 2006-12-27 2009-11-18 TruePosition, Inc. Localisation sans abonnement de dispositifs sans fil
US11729039B2 (en) 2020-08-31 2023-08-15 Sinclair Broadcast Group, Inc. ATSC 3.0 single frequency networks used for positioning navigation timing and synergy 4G / 5G networks

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