JP2005512103A - Positioning using terrestrial digital integrated broadcasting service (ISDB-T) TV broadcasting signal - Google Patents

Abstract

  A method and apparatus for determining the position of a user terminal and a computer readable medium include receiving a digital television (DTV) broadcast signal at a user terminal from a DTV transmitter, wherein the DTV signal is integrated with a terrestrial digital integrated broadcast service ( ISDB-T) signal, based on determining the pseudorange between the user terminal and the DTV transmitter based on the known component of the DTV broadcast signal, and on the basis of the pseudorange and the position of the DTV transmitter It consists in determining the position of the user terminal.

Description

Cross-reference of related applications

  This application includes US patent application Ser. No. 10 / 210,847 “Positioning Using Digital Broadcast Television Signals” filed July 31, 2002 by James J. Spielker Jr. and Matthew Rabinowitz, Matthew US Patent Application No. 09 / 932,010 “Positioning Using Terrestrial Digital Video Broadcasting TV Signals” filed August 17, 2001 by Rabinowitz and James J. Spielker Jr., James J. US patent application Ser. No. 10 / 209,578 “Time-Gate Incoherent Delayed Locked Loop Tracking of Digital Television Signals” filed July 31, 2002 by Spilker and Matthew Rabinowitz, Matthew Rabinowitz and James May 3, 2002 by J. Spielker It is a continuation-in-part application of a "position location using global positioning signal amplified by the TV signal" filed US patent application Ser. No. 10 / 159,478 a day.

  This application also includes US Provisional Patent Application No. 60 / 337,834 “Radio Location Using Japanese ISDB-T Digital Television Signals” filed November 9, 2001 by James J. Spielker, US Provisional Patent Application No. 60 / 265,675, filed February 2, 2001 by Matthew Rabinowitz and James J. Spielker, for navigation and / or data communication using satellite and / or terrestrial structure infrastructure System and Method ", and US Provisional Patent Application No. 60 / 281,270" ETSI DVB Terrestrial Digital Broadcasting for High-Accuracy Positioning on Mobile Radio Links "filed April 3, 2001 by James J. Spielker Use of TV Signals ", 2 by James J. Spielker and Matthew Rabinowitz US Provisional Patent Application No. 60 / 281,269, filed April 3, 2001, "ATSC Standard DTV Channel for Low Data Rate Broadcast to Mobile Receivers", by James J. Spielker and Matthew Rabinowitz On May 25, 2001 by US Provisional Patent Application No. 60 / 293,812 “DTV Monitor System Unit (MSU)” filed May 25, 2001, James J. Spielker and Matthew Rabinowitz. Claims benefit of filed US Provisional Patent Application No. 60 / 293,813 “DTV Positioning Range and Signal to Noise Ratio Performance”.

  All prior art subject lines are hereby incorporated by reference.

  The present invention relates generally to position determination, and more particularly to position determination using digital television (DTV) signals.

  A method of a two-dimensional latitude / longitude location system using wireless signals has long existed. Terrestrial systems such as Loran C and Omega existed in a wide range of usage, and were satellite-based systems known as transits. Another satellite-based system that has enjoyed increasing popularity is the Global Positioning System (GPS).

  GPS was first devised in 1974 and is widely used for location, navigation, surveying, and time transfer. The GPS system is based on a group of 24 on-orbit satellites in sub-synchronous 12-hour orbits. Each satellite has a precision clock and transmits a pseudo-noise signal. It can be tracked precisely to determine the pseudorange. By tracking four or more satellites, the position in three dimensions can be accurately determined in real time. More details can be found in BW Parkinson and JJ Spirker Jr. "Global Positioning System-Theory and Application", Volumes 1 and 2, AIAA, Washington, DC, 1996.

  GPS has revolutionized navigation and positioning technology. However, in some situations, GPS is less effective. GPS signals are propagated over long distances at relatively low power levels (less than 100 watts) and the received signal strength is relatively weak (approximately -160 dBw received by an omnidirectional antenna). Thus, the signal is slightly useful or not useful at all in the presence of obstructions or in the building.

  Systems using conventional analog National Television System Committee (NTSC) television signals to determine position have been proposed. This proposal can be found in US Pat. No. 5,510,801 issued on Apr. 23, 1996 entitled “Positioning System and Method Using Television Broadcast Signals”. However, existing analog television signals include horizontal and vertical sync pulses, which are intended for relatively coarse synchronization of television set scanning circuits. Further, in 2006, the Federal Communications Commission (FCC) could be auctioned for other more valuable purposes in view of NTSC transmitter turn-off and beneficial spectrum reassignment.

Summary of the Invention

  In general, in one aspect, the invention is characterized by a method, apparatus, and computer-readable medium for determining the position of a user terminal. It receives a digital TV broadcast signal (DTV) from a DTV transmitter at the user terminal, and the DTV signal is composed of a terrestrial digital integrated broadcast service signal, which is based on a known component in the broadcast DTV signal. It consists of determining the pseudo distance between the terminal and the DTV transmitter and determining the position of the user terminal based on the pseudo distance and the position of the DTV transmitter.

  An exemplary embodiment can include one or more of the following features. Determining the position of the user terminal includes adjusting the pseudorange based on the difference between the transmitter clock at the DTV transmitter and a known time reference, and adjusting the pseudorange and the position of the DTV transmitter. And determining the position of the user terminal. The known component is a dispersed pilot carrier. The user terminal position is determined by determining an offset between the local time reference and the master time reference at the user terminal, and determining the position of the user terminal based on the pseudorange, the position of the DTV transmitter, and the offset. Become. An embodiment consists of determining the continuous position of the user terminal using the offset. The determination of the pseudorange consists of storing a part of the DTV signal and continuously correlating the stored part and the signal generated by the user terminal to obtain the pseudorange. Determining the pseudorange while receiving the DTV signal and obtaining the pseudorange consists of correlating the DTV signal with the signal generated by the user terminal. User terminal position determination is based on determining the general geographical range within which the user terminal is located and determining the user terminal position based on the pseudorange and the general geographical range. Become. The general geographical range is a radio wave coverage of another transmitter that is communicably connected to the user terminal. The user terminal position is determined by determining the tropospheric propagation speed in the vicinity of the user terminal, adjusting the pseudorange based on the tropospheric propagation speed, and the user based on the adjusted pseudorange and the position of the DTV transmitter. It consists in determining the location of the terminal. The user terminal position is determined by adjusting the pseudo distance based on the altitude of the terrain near the user terminal, and determining the position of the user terminal based on the adjusted pseudo distance and the position of the DTV transmitter. Become. An embodiment comprises selecting a DTV signal from a plurality of DTV signals based on the identity of another transmitter communicatively connected to the user terminal and a storage table that correlates the other transmitter with the DTV signal. The embodiment comprises receiving position information input from a user and selecting a DTV signal from a plurality of DTV signals based on the position information input. The embodiment scans the available DTV signals to collect position fingerprints and causes the DTV signals used to determine pseudoranges to match fingerprints and known fingerprints to known positions. And selecting from available DTV signals based on the storage table. An embodiment consists of using receiver automatic integrity monitoring (RAIM) and checking the pseudorange integrity based on redundant pseudoranges from the DTV transmitter.

  In general, in one aspect, the invention features a method, apparatus, and computer-readable medium for determining the location of a user terminal. It receives a digital television (DTV) broadcast signal from a DTV transmitter at the user terminal, where the DTV signal consists of the European Telecommunications Standards Institute (ETSI) digital video broadcast-terrestrial (ISDB-T) signal. Position information configured to determine a pseudo distance between the user terminal and the DTV transmitter based on the DTV broadcast signal, and to determine the position of the user terminal based on the pseudo distance and the position of the DTV transmitter It consists of sending a pseudorange to the server.

  Exemplary embodiments can include one or more of the following features. The pseudo-range is determined by determining the transmission time of the known component of the DTV broadcast signal from the DTV transmitter, determining the reception time of the known component at the user terminal, and the transmission time and the reception time. Consists of determining the difference between. The known component is a distributed pilot carrier. The determination of the pseudorange consists of storing a part of the DTV signal and obtaining the pseudorange by continuously correlating the stored part with the signal generated by the user terminal. The determination of the pseudorange consists of correlating the DTV signal with a signal generated by the user terminal to receive the DTV signal and obtain the pseudorange.

  In general, in one aspect, the invention features a method, apparatus, and computer readable medium for user terminal location. It receives a pseudorange from a user terminal, and the pseudorange is determined between the user terminal and the DTV transmitter based on the DTV signal broadcast by the DTV transmitter, where the DTV signal is ETSI) digital video broadcast-terrestrial (ISDB-T) signal, the pseudorange is determined based on known components of the ISDB-T signal, and based on the pseudorange and the position of the DTV transmitter Consists of determining the position.

  Exemplary embodiments can include one or more of the following features. The positioning of the user terminal is based on the adjustment of the pseudorange based on the difference between the transmitter clock at the DTV transmitter and the known time reference, and the adjusted pseudorange and the position of the DTV transmitter. And determining the location of the user terminal. The known component is a dispersed pilot carrier. Determination of the position of the user terminal includes determination of an offset between the local time reference and the master time reference at the user terminal, and determination of the position of the user terminal based on the pseudorange, the position of the DTV transmitter, and the offset. An embodiment consists of determining the continuous position of the user terminal using the offset. The determination of the user terminal position includes determination of a general geographical range in which the user terminal is positioned within the range, and determination of the position of the user terminal based on the pseudorange and the general geographical range. Its general geographical range is the radio wave coverage of another transmitter communicatively connected to the user terminal. The user terminal position is determined by determining the tropospheric propagation speed in the vicinity of the user terminal, adjusting the pseudorange based on the tropospheric propagation speed, and the position of the user terminal based on the adjusted pseudorange and the position of the DTV transmitter. Of the decision. The determination of the position of the user terminal includes adjustment of the pseudo distance based on the altitude of the terrain in the vicinity of the user terminal, and determination of the position of the user terminal based on the adjusted pseudo distance and the position of the DTV transmitter.

  Advantages found in embodiments of the invention include one or more of the following. Embodiments of the present invention may be used to locate mobile phones, wireless PDAs (Personal Digital Assistants), pagers, automobiles, OCDMA (Orthogonal Code Division Multiplexing) transmitters, and many other devices. . Embodiments of the present invention utilize DTV signals with good coverage. Embodiments of the present invention do not require a change to a digital broadcast station.

  DTV signals have a power advantage over GPS of over 50 dB and have a shape that is substantially better than what a satellite system can provide, thereby enabling positioning in the presence of obstructions or indoors . The DTV signal is approximately 8 times the GPS bandwidth, thereby minimizing the effects of multipath. The processing conditions are minimal due to the high frequency and the slight frequency content of the DTV signal used for distance measurement. Embodiments of the present invention provide a much cheaper, slower and lower power device than GPS technology requires.

  In contrast to satellite systems such as GPS, the distance between the DTV transmitter and the user terminal changes very slowly. Therefore, the DTV signal is not significantly affected by the Doppler effect. This allows the signal to be integrated over a long time, resulting in a very efficient signal acquisition.

  The frequency of the DTV signal is substantially lower than the frequency of the conventional mobile phone system and has better propagation characteristics. For example, DTV signals experience greater diffraction than portable signals, are less susceptible to mounds, and have larger horizontal lines. Also, the signal has better propagation characteristics depending on the building or the car. In addition, embodiments of the present invention utilize components of the ISDB-T signal, which are continuous and constitute a large percentage of the power of the ISDB-T signal.

  Unlike terrestrial arrival angle / arrival time positioning systems for mobile phones, embodiments of the present invention do not require changes in mobile base station hardware and achieve positioning accuracy of approximately 1 meter. Can do. When used for mobile phone location determination, the technology includes GSM (Global System Mobile), AMPS (Advanced Mobile Phone Service), TDMA (Time Division Multiple Access), CDMA, etc., regardless of the air interface. A wide range of UHF frequencies has been assigned to DTV transmitters. As a result, there is redundancy built into the system that protects against extreme fades on specific frequencies due to absorption, multipath, and other attenuation effects.

  The details of one or more aspects of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.

Detailed Description of the Invention

Introduction Digital television (DTV) is gaining popularity. DTV was first implemented in the United States in 1998. As of the end of 2000, there were 167 stations broadcasting DTV signals. As of February 28, 2001, approximately 1200 DTV construction permits were approved by the FCC. According to FCC policy, all television transmissions will soon be digital and analog signals will be removed. Public broadcasters must be digitized by 1 May 2002 in order to retain their licenses. The private sector must have been digitized by 1 May 2003. More than 1600 DTV transmitters are expected in the United States. Other regions implement similar DTV systems. The Japan Broadcasting Corporation (NHK) clarifies the terrestrial DTV signal for Japan and is referred to herein as the terrestrial digital integrated broadcasting service (ISDB-T) signal. These new DTV signals allow multiple television signals to be transmitted on the assigned 6 MHz channel. These new ISDB-T DTV signals are completely different from analog NTSC TV signals and have completely new capabilities. The inventor has recognized that the ISDB-T signal can be used for position location and has developed a technique for doing so. These techniques can be used in the vicinity of the ISDB-T DTV transmitter and at a distance farther from the transmitter than the typical TV reception distance. Because of the high power of DTV signals, these techniques can also be used indoors with portable receivers, thus providing a possible solution to the positioning needs of the Extended 911 (E911) system.

  The techniques disclosed herein can be applied to other DTV signals, including a known data sequence by simply modifying the correlator and accommodating that known data sequence. This will be apparent to those skilled in the relevant art. These techniques can also be applied to a range of other orthogonal frequency division multiplication (OFDM) signals, such as satellite radio signals.

  In contrast to GPS digital pseudo-noise codes, DTV signals are received from transmitters that are only a few miles away, which broadcast signals with an effective radiated power of up to several hundred kilowatts. Furthermore, the DTV transmitter antenna has a large antenna gain of approximately 14 dB. Thus, sufficient power is frequently present to enable DTV signal reception in the building.

  As described below, embodiments of the present invention utilize components of the ISDB-T signal and are referred to as “distributed pilot signals”. The use of a distributed pilot signal is advantageous for several reasons. First, it allows position determination indoors and at a considerable distance from the DTV transmitter. Conventional DTV receivers use only one data signal at a time and are limited to the distance from the DTV transmitter by the energy of a single signal. In contrast, embodiments of the present invention simultaneously utilize the energy of a multi-distributed pilot signal, thereby allowing operation at a greater distance from the DTV transmitter than a conventional DTV receiver. Furthermore, the distributed pilot is not modulated with data. This is advantageous for two reasons. First, all power in the distributed pilot is available for position determination, and no power is devoted to data. Second, distributed pilots can be observed for a long time without suffering degradation that causes data modulation. Thus, the ability to track signals indoors at a substantial distance from the DTV tower is greatly expanded. In addition, these new tracking techniques can be implemented on a single semiconductor chip through the use of digital signal processing.

  Referring to FIG. 1, an example 100 includes a user terminal 102 that communicates with a base station 104 via an air battle. In one embodiment, user terminal 102 is a radiotelephone and base station 104 is a radiotelephone base station. In one embodiment, the base station 104 is part of a mobile MAN (Metropolitan Area Network) or WAN (Wide Area Network).

  Although FIG. 1 is used to illustrate various aspects of the present invention, the present invention is not limited to this example. For example, the phrase “user terminal” is meant to refer to any object capable of performing the described DTV location. Examples of user terminals include PDAs, mobile phones, cars and other vehicles, any object that can include a chip or software that implements DTV location. It is not intended to be limited to objects that are “terminals” or objects that are manipulated by a “user”.

Position location FIG. 2 implemented by the DTV location information server illustrates the operation of the embodiment 100. The user terminal 102 receives DTV signals via a plurality of DTV transmitters 106A and 106B to 106N (step 202).

  Various methods can be used to select which DTV channel to use for location. In one embodiment, the DTV location information server 110 tells the user terminal 102 the best DTV channel to monitor. In one embodiment, user terminal 102 exchanges messages with DTV location information server 110 via base station 104. In one embodiment, user terminal 102 selects a DTV channel and monitors based on the identity of base station 104 and a storage table that correlates the base station and the DTV channel. In another embodiment, the user terminal 102 can receive location information input from a user that gives a general indication of the area, such as the name of the nearest city, and uses this information to select a processing DTV channel. In one embodiment, the user terminal 102 scans the available DTV channels and collects a location fingerprint based on the power levels of the available DTV channels. The user terminal 102 selects a processing DTV channel by comparing the fingerprint with a storage table that matches a known fingerprint with a known position. This selection is based on the power level of the DTV channel as well as its direction, and each signal arrives from that direction, minimizing position calculation precision dilution (DOP).

  The user terminal 102 determines a pseudo distance between the user terminal 102 and each DTV transmitter 106 (step 204). Each pseudo distance is the time difference (or equivalent distance) between the transmission time of the component of the DTV broadcast signal from the transmitter 108 and the reception time of the component at the user terminal 102 as well as the clock offset at the user terminal. Represent.

  The user terminal 102 transmits the pseudo distance to the DTV position information server 110. In one embodiment, DTV location information server 110 is implemented as a general purpose computer executing software designed to perform the operations described herein. In another embodiment, the DTV location information server is implemented as an ASIC (Application Specific Integrated Circuit). In one embodiment, the DTV location information server 110 is implemented in or near the base station 104.

  The DTV signal is received by the plurality of monitor devices 108A to 108N. Each monitoring device can be implemented as a small device including a transceiver and a processor. It can be mounted at a convenient location such as a utility pole, DTV transmitter 106 or base station 104. In one embodiment, the monitoring device is implemented on a satellite.

  Each monitoring device 108 measures the time offset between the local clock of the DTV transmitter and the reference clock for each DTV transmitter that receives the DTV signal. In some embodiments, the reference clock is derived from a GPS signal. Using a reference clock allows determination of the time offset for each DTV transmitter 106 when multiple monitor devices 108 are used. This is because the monitoring device 108 can determine the time offset with respect to the reference clock. Thus, the offset in the local clock of the monitor device 108 does not affect these decisions.

  In another embodiment, no external time reference is required. According to this embodiment, a single monitoring device receives DTV signals from the same full DTV transmitter that user terminal 102 receives. Eventually, a single monitor device local clock serves as a time reference.

  In one embodiment, each time offset is modeled as a fixed offset. In another embodiment, each time offset is modeled as a second order polynomial fit of the following expression represented by a, b, c and T:

Offset value = a + b (t−T) + c (t−T) ² (1)
In either embodiment, each measurement time offset is periodically transmitted to the DTV location information server using the Internet, a secure modem connection, etc. as part of the actual DTV broadcast data. In one embodiment, the position of each monitoring device 108 is determined using a GPS receiver.

  The DTV position information server 110 receives information representing the phase center (ie, position) of each DTV transmitter 106 from the database 112. In one embodiment, each DTV transmitter 106 phase center is measured using a monitor device 108 at a different location to directly measure the phase center. An approach to do this is to use a multiple time synchronization monitor with known location information. These devices make pseudorange measurements to the television transmitter at the same moment. These measurements can then be used to reverse the position of the television transmitter phase center. In another embodiment, the phase center of each DTV transmitter 106 is measured by examining the antenna phase center. Once determined, the phase center is stored in the database 112.

  In one embodiment, the DTV location information server 110 receives weather information representing temperature, atmospheric pressure, and humidity in the vicinity of the user terminal 102 from the weather information server 114. Weather information is available from the Internet and other sources. The DTV position information server 110 determines the tropospheric propagation speed from the weather information. To that end, B. Parkinson and J. Spielker, Jr. "Global Positioning System-Theory and Applications", AIAA, Washington, DC (1996), Vol. 1, Chapter 17, J. Spirker, Jr. The technology is being used.

  The DTV location information server 110 may also receive information identifying the general geographical location of the user terminal 102 from the base station 104. For example, the information can identify the cell or cell sector where the mobile phone is located. This information is used for ambiguity resolution as follows.

  The DTV position information server 110 determines the position of the user terminal based on the pseudorange, the position of each transmitter, and the clock offset (step 206). FIG. 3 represents a location determination configuration using three DTV transmitters 106. The DTV transmitter 106A is positioned at the position (x1, y1). The distance between the user terminal 102 and the DTV transmitter 106A is r1. The DTV transmitter 106B is positioned at the position (x2, y2). The distance between the user terminal 102 and the DTV transmitter 106B is r2. The DTV transmitter 106N is positioned at the position (x3, y3). The distance between the user terminal 102 and the DTV transmitter 106N is r3.

  The DTV position information server 110 may adjust the value of each pseudo distance according to the tropospheric propagation velocity and the corresponding time offset with respect to the DTV transmitter 106. The DTV position information server 110 uses the phase center information from the database 112 to determine the position of each DTV transmitter 106.

  The user terminal 102 measures three or more pseudoranges and solves three unknowns, that is, the position (x, y) of the user terminal 102 and the clock offset T. In one embodiment, the techniques disclosed herein are used to determine a position in three dimensions such as longitude, latitude, and height, and can include factors such as the height of the DTV transmitter.

  Three pseudorange measurements pr1, pr2, pr3 are given by:

pr1 = r1 + T (2)
pr2 = r2 + T (3)
pr3 = r3 + T (4)
The three distances can be expressed as:

r1 = | X−X1 | (5)
r2 = | X−X2 | (6)
r3 = | X−X3 | (7)
Here, X represents the two-dimensional vector position (x, y) of the user terminal, X1 represents the two-dimensional vector position (x1, y1) of the DTV transmitter 106A, and X2 represents the two-dimensional vector position of the DTV transmitter 106B ( x2, y2), and X3 represents the two-dimensional vector position (x3, y3) of the DTV transmitter 106N. These relationships yield three equations that solve the three unknowns x, y, and T. The DTV location information server 110 solves these equations in a conventional and well known manner. With the application of E911, the location of the user terminal 102 is transmitted to the E911 location information server 116 for distribution to the relevant authorities. In another application, the location is transmitted to the user terminal 102.

  Now, a technique for projecting measured values at the user terminal 102 at a normal moment is described. Note that this is not necessary if the clock of the user terminal 102 is stabilized or corrected using signals from the mobile base station or DTV transmitter 106. When the user clock is not stabilized or corrected, the user clock offset can be considered as a function of time T (t). For small time intervals Δ, the clock offset T (t) can be modeled by a constant and a first order term. That is, the following formula.

  Now consider equation (2a)-(4a) dealing with clock offset as a function of time. As a result, pseudorange measurements are also a function of time. For simplicity, assume that the distance remains substantially constant at the interval Δ. The pseudorange measurements are described as follows:

pr1 (t1) = r1 + T (t1) (2b)
pr2 (t2) = r2 + T (t2) (3b)
prN (tN) = rN + T (tN) (4b)

  In one embodiment, user terminal 102 starts with an additional set of pseudorange measurements at a time Δ after the first set of measurements. These measurements may be described.

  Thereafter, the user terminal 102 projects all pseudorange measurements to normal time points, effectively removing the influence of the first order term. For example, consider the case where several normal reference times t0 are used. Applying equations (2b-4b) and (2c-4c) is straightforward to show that measurements can be projected at normal moments as follows:

  These projected pseudorange measurements are linked to a location information server, where they are used to solve the three unknowns x, y, T. Note that the projections in equations (2d-4d) are not precise, so that the quadratic terms are not accounted for. However, the resulting error is not critical. Those skilled in the art will recognize that second and higher order terms may be accounted for by measuring more than two pseudoranges for each projection. It should also be noted that there are many other approaches that implement this concept of projecting pseudo measurements at the same moment. One approach is to implement a delay locked loop, for example. JJ Spielker Jr.'s "Digital Communications by Satellite" Prentice Hall, Inglewood Cliff, New Jersey (1977) (1995), and BW Parkinson and JJ Spielcar Jr. Earth Positioning System-Theory and Application, "Volume 1 AAAA, Washington DC, (1996), etc., both of which are hereby incorporated by reference. A separate tracking loop can be dedicated to each DTV transmitter 106. These tracking loops effectively interpolate between pseudorange measurements. The state of each of these tracking loops is sampled at the same instant.

  In another embodiment, user terminal 102 does not calculate pseudoranges, but measures DTV signals sufficient to calculate pseudoranges, such as segments of correlator output, and causes DTV location information server 110 to measure these measurements. Send. Thereafter, the DTV position information server 110 calculates a pseudo distance based on the measurement value, and calculates a position based on the pseudo distance as described above.

In another example of position location performed by the user terminal, the position of the user terminal 102 is calculated by the user terminal 102. In this embodiment, all necessary information is transmitted to the user terminal 102. This information can be transmitted to the user terminal by the DTV location information server 110, the base station 104, one or more DTV transmitters 106, or a combination thereof. Thereafter, the user terminal 102 measures the pseudorange and solves the simultaneous equations. This example will now be described.

  The user terminal 102 receives the time offset between the local clock of each DTV transmitter and the reference clock. In addition, the user terminal 102 receives information representing the phase center of each DTV transmitter 106 from the database 112.

  The user terminal 102 receives the tropospheric propagation velocity calculated by the DTV location information server 110. In another embodiment, the user terminal 102 receives weather information representing the temperature, atmospheric pressure, and humidity near the user terminal 102 from the weather information server 114. The tropospheric propagation speed is then determined from the weather information using conventional techniques.

  Further, the user terminal 102 can receive information identifying the rough position of the user terminal 102 from the base station 104. For example, the information can identify the cell or cell sector where the mobile phone is located. This information is used in the following ambiguity resolution.

  The user terminal 102 receives DTV signals from a plurality of DTV transmitters 106 and determines a pseudo distance between the user terminal 102 and each DTV transmitter 106. The user terminal 102 then determines its position based on the pseudorange and the phase center of the transmitter.

  In some of these embodiments, only two DTV transmitters should be available, and the location of the user terminal 102 uses two DTV transmitters and an offset T calculated during the previous position determination. Can be determined. The value of T can be stored or maintained by conventional methods. Of course, this assumes that the local clock is sufficiently stable during the time since T was calculated.

  In one embodiment, base station 104 determines a clock offset for user terminal 102. In this embodiment, only two DTV transmitters are required for position determination. The base station 104 transmits the clock offset T to the DTV position information server 110, and then determines the position of the user terminal 102 from the pseudo distance calculated for each DTV transmitter.

  In another embodiment, if only one or two DTV transmitters are available for position determination, GPS is used to increase position determination, and each GPS satellite is a separate transmitter in the position solution. Are treated as

Receiver Structure FIG. 4 shows a receiver embodiment 400 used to generate pseudorange measurements. In certain embodiments, receiver 400 is implemented within user terminal 102. In another embodiment, receiver 400 is implemented within monitoring device 108.

Tuner 406 is measured by clock 416 and causes DTV signal 402 to tune antenna 404 in the area in response to a control signal provided by tuner controller 420. In some forms, tuner 406 also downconverts the received DTV signal to an intermediate frequency (IF). Mixers 408I and 408Q combine the carrier signal generated by carrier generator 418 with the tuned DTV signal to generate an in-phase square DTV signal at intermediate frequency (IF) or baseband. In one form, clock 416 runs at 27 MHz. Each of these signals is filtered by one of filters 410I and 410Q, digitized by one of analog-to-digital converters (A / D) 411I and 411Q, and the signals m [t−T] and q [t−T ] Are respectively generated. In another form, a single A / D converter with a switch is used to alternately sample in-phase and square channels. The correlator 412I combines the signal m [t−T] with the synchronization signal s [t−T ^* ] and provides the correlation output to the search controller 414.

The delay locked loop 422 includes a correlator 412Q, a filter 424, a numerically controlled oscillator (NCO) 426 measured by a clock 416, and a synchronization generator 428 that generates a digital representation of the distributed pilot signal. The correlator 412Q combines the signal q [t−T] with the synchronization signal s [t−T ^* ], filters the signal with the filter 424, and gives the correlation output to the NCO 426. The NCO 426 drives the synchronization generator 428 by the search controller 414.

  Control is performed by the search controller 414 during signal acquisition, and by the NCO 426 during signal tracking after acquisition. The pseudorange is obtained by sampling the NCO 426.

  It should be noted that when a telephone subscriber needs location, a location operation on the subscriber's handset or other device need only be performed. For subscribers who are slowly walking in a slowly moving vehicle or who are sitting in buildings or fields in an emergency, this location information only needs to be measured occasionally. Thus, the battery or power source may be very small.

  Of course, other versions of the receiver 400 can be implemented using the above concept, for example, by processing the received DTV signal using Fast Fourier Transform (FFT). Furthermore, the sum of nine chirp signals or all 117 chirp carriers can simply be digitized and performed in a suboptimal manner.

  Important to achieve this performance is the concept of correlating with 9 in at least a single segment, correlating in parallel with all the distributed pilots. The wide bandwidth of the composite signal gives a more accurate position location. Timing accuracy is inversely proportional to bandwidth.

  Also, other signals in the ISDB-T structure can be used for position location. For example, wide lane techniques can be applied to continuous pilot signals. However, techniques such as wide learning include a unique solution for periodic ambiguity. Techniques for resolving such ambiguities are well known in the art.

  User terminal local oscillators often have relatively poor frequency. This instability affects two different receiver parameters. First, it causes a frequency offset in the receiver signal. Second, it causes a received bit pattern that is reduced compared to the symbol rate of the reference clock. Both of these effects can limit the integration time of the receiver and thus limit the processing gain of the receiver. The integration time can be increased by correcting the receiver reference clock. In one embodiment, the delay locked loop automatically corrects for the receiver clock.

A priori knowledge of the location of the location-based extension mobile phone site can be used to extend the location determination. This is conceptually illustrated in FIG. 5, which illustrates a simplified example of a location calculation for a user terminal 102 that receives DTV signals from two separate DTV antennas 106A and 106B. For this simplified example, it is assumed that the user's clock offset is already known. Based on distance measurements, circles with a fixed distance 502A and 502B are drawn around the propagation antennas 106A and 106B, respectively. The location of the user terminal includes a correction value for the user terminal clock offset and then is one of the intersections 504A and 504B of the two circles 502A and 502B. The ambiguity is resolved by noting in which sector 508 of the radio wave coverage 506 (ie broadcast range) where the user terminal is located can be determined by the base station 104. Of course, if there are more than two DTV transmitters in the figure, the ambiguity can be resolved by taking the intersection of three circles. Since the synchronization code from the television transmitter is inherently repetitive, there is a period ambiguity, which is determined by the repetition period of the television synchronization code, and the speed of light causes a distance ambiguity equal to the number of repetition periods. This periodic ambiguity is true by example when the distance ambiguity is large compared to the size of the cell site, but can then be resolved by the same technique described in the simplified example of FIG. Good.

  In one embodiment, instead of using a cell site that first determines a rough location, the user terminal 102 can receive input from a user providing general instructions for the area, such as the name of the nearest city. In one embodiment, the user terminal 102 scans the available DTV channels and collects a location fingerprint representing a set of visible channels. The user terminal 102 compares this fingerprint with the storage table. This storage table matches the known fingerprint with the known location to identify the current rough location of the user terminal 102.

  In one embodiment, the location calculation includes the effect of ground height. Thus, on terrain with hills and valleys, the circle of a certain distance is distorted compared to the phase center of the DTV antenna 106. FIG. 6 represents the effect of a single hill 604 on a circle at a constant distance 602 on a DTV transmitter 106 located at the same altitude as the surrounding land.

  Calculation of the user's position is easily done by a simple computer having as its database a regional topographic map that allows the calculation to include the height of the user on the earth's surface, the influence of geoids. This calculation has the effect of distorting a circle of a certain distance as shown in FIG.

ISDB-T Signal Description The ISDB-T signal is a composite orthogonal frequency division multiplex (OFDM) signal that carries a 188 byte MPEG (International Standard for Video Compression and Decompression) packet, 1512 or Either 6048 separate carriers are used. Most of these components carry random data modulation of video television signals and are less useful for accuracy tracking at low signal levels. Note that for location purposes, the user terminal may be in a location where the full information content of the ISDB-T signal is not available.

  The ISDB-T signal is a band division transmission (BST) orthogonal frequency division multiplexing (OFDM) signal and has the capability to deliver various video, voice, and data services. Since it is an OFDM system, it withstands multipath. With so-called band division transmission, it is possible to be flexible in the transmitted information. The segment has a bandwidth of 3000/7 = 428.5714286 kHz.

  The ISDB-T signal contains a synchronization component, which is very useful for position location. The signal has both wideband and narrowband formats. The wideband format has a bandwidth of 5.6 MHz and is used for television and data. The narrowband format has a bandwidth of 430 KHz and is used for lower bandwidth signaling. The signal characteristics of the three modes of the wideband format are listed in Table 1. Carrier spacing is the inverse of useful symbol duration. Coherent modulation segments have distributed pilots, and different coherent segments have continuous pilots. For each mode, the total number of segments is Ns = 13 = ns + nd. In this section, one of the three modes of the wideband format is described, however, the same concept applies to all three modes.

  The wideband signal is composed of 13 OFDM segments, and each segment is composed of 108 frequencies. The bandwidth of the 108 carrier OFDM segment is 430 kHz. An OFDM carrier is modulated with video information, usually in the MPEG-2 format, using square amplitude modulation (QAM) and strong error correction coding. However, some of the 108 frequency sets are excluded for synchronization. These are so-called distributed and continuous pilots. Some forms of the invention use a continuous pilot for central frequency measurement. However, distributed pilots are more advantageous for high precision position measurement.

  The ISDB-T standard includes differential square phase shift keying (DQPSK), square phase shift keying (QPSK), 16QAM and 64QAM, 1/2, 2/3, 3/4, 5/6, and 7/8. Many modulation schemes are provided, including the coding rate for the inner code. These parameters can be selected independently for each segment. The total data rate for the wideband mode is only 3.651 Mbps for differential interferometric modulation DQPSK. The narrowband single segment mode produces a data rate of 280.85 kbps and a rate 1/2 coding for DQPSK modulation. The other mode is coherent and produces data rates up to 23.234 Mbps for 64QAM mode with an inner code of rate 7/8.

  There are 35 distributed pilots in each of the 13 OFDM segments. Thus, there are a total of 468 distributed pilots in each wideband DTV signal among all 13 segments. Within the OFDM segment, the distributed pilot changes frequency for each symbol. The amount of frequency jump is 3 carriers. The same carrier is transmitted for one symbol having a pattern that repeats every four symbols. Thus, as shown in FIG. 7, there are several distributed pilots that transmit all at once. The maximum dispersion pilot frequency is 105 in FIG.

  As seen in FIG. 7, this set of distributed pilots can be viewed as 9 distributed pilots, each flying 3 carriers per symbol. A good approximation is nine “chirp” carriers for each of the 13 segments for a total of 117 distributed pilots.

  The bandwidth of these distributed pilots is substantially flat across the spectral occupancy region, but it is clear that it has a line component at a periodic rate of 4 symbols. However, the 4-symbol period represents a very large distance due to the relatively low symbol rate. Thus, the ambiguity caused by the signal is negligible and is easily resolved.

  The composite distributed pilot signal can be written as s [t] and can be represented in digital form. It is an ATSC delay lock described in Patent Application No. 10 / 210,847 “Positioning Using Digital Broadcast Television Signals” filed July 31, 2002 by James J. Spielker Jr. and Matthew Rabinowitz. This is the same as the pseudo noise signal used in the loop and the correlator. Although the exact format of the ISDB-T signal is different, signal tracking can be performed in a similar manner using the reference signal s [t].

  Furthermore, the ISDB-T signal was recorded in August 1999 by S. Nakahara et al. Of IEEE Transaction on Consumer Electronics, "Digital Transmission Scheme for ISDB-T and Reception Characteristics of Digital Terrestrial Television Broadcasting in Japan," 1999. It is described in “Transmission scheme for terrestrial ISDB system” by M. Uehara et al. Of IEEE Transaction on Consumer Electronics in February.

Signal Segment Autocorrelation Function A single segment of 108 carriers contains 36 distributed pilots with 3 device frequency spacing. The transmitted tone sequence repeats every 105/3 = 35 symbols. The coherent autocorrelation function of this signal for a single segment is calculated assuming a sample rate of 1/400 symbols and is shown in FIG. An autocorrelation width for a single segment of about 430 kHz can provide a temporal resolution of about 1 microsecond. The use of the full bandwidth of the signal with 13 segments and the correlation over the whole frequency range attenuates the autocorrelation peak at the same rate as about 1000/13 = 77 ns or 77 feet. If there is sufficient signal-to-noise ratio and no multipath error, pseudorange accuracy of about 5 meters or more is possible.

Monitor Device FIG. 9 illustrates an embodiment 900 of the monitor device 108. The antenna 904 receives the GPS signal 902. The GPS time transfer device 906 enhances the master clock signal based on the GPS signal. In order to determine the offset of the DTV transmitter clock, an NCO (Numerically Controlled Oscillator) code synchronization timer 908A develops a master synchronization signal based on the master clock signal. The master synchronization signal can include an ISDB-T distributed pilot carrier. In one embodiment, among all monitoring devices 108, NCO synchronization timer 908A is synchronized to the base date and time. In one embodiment, a single monitoring device 108 receives DTV signals from all the same DTV transmitters received by the user terminal 102, and uses any other monitoring device for the purpose of determining the location of the user terminal 102. There is no need to synchronize the monitoring device 108 provided. If all monitor stations 108 or all DTV transmitters are synchronized to a normal clock, such synchronization is also unnecessary.

  The DTV antenna 912 receives a plurality of DTV signals 910. In another embodiment, multiple DTV antennas are used. The amplifier 914 amplifies the DTV signal. One or more DTV tuners 916A through 916N each tune to the DTV channel with the received DTV signal to generate a DTV channel signal. Each of the plurality of NCO code synchronization timers 908B to 908M receives one of the DTV channel signals. Each of the NCO code synchronization timers 908B to 908M extracts a channel synchronization signal from the DTV channel signal. The channel synchronization signal can include an ISDB-T distributed pilot carrier. In one embodiment, the continuous pilot signal and symbol timing in the ISDB-T signal are used as acquisition aids.

  Each of the plurality of analog adders 918A to 918N generates a clock offset between the master synchronization signal and one of the channel synchronization signals. The processor 920 sends the data resulting from the formatting to the DTV location information server 110. In one embodiment, this data includes the number of DTV transmitters identified for each DTV channel being measured, the number of DTV channels, the antenna phase center for the DTV transmitter, and the clock offset. This data can be transmitted by several of many methods including antennas and the Internet. In one embodiment, the data is broadcast in spare MPEG packets on the DTV channel itself. The clock offset for each channel may also be modeled as a function of time.

One complete approach to mitigating the effects of software receiver multipath is to sample the total autocorrelation function rather than using only early and late samples, such as in hardware setup. Multipath effects can be mitigated by selecting an initial correlation peak.

  If the position can be calculated with a simple delay, a simple approach is to use a software receiver, which samples a filtered sequence of signals and then processes the firmware samples on a digital signal processor To do.

  FIG. 10 illustrates an embodiment 1000 for a software receiver. The antenna 1002 receives a DTV signal. The antenna 1002 may be a magnetic dipole or any other type of antenna capable of receiving a DTV signal. Bandpass filter 1004 passes the entire DTV signal spectrum to LNA 1006. In one embodiment, filter 1004 is a tunable bandpass filter that passes the spectrum for a particular DTV channel under the control of a digital signal processor (DSP) 1014.

A low noise amplifier (LNA) 1006 amplifies the selected signal and passes it to the DTV channel selector 1008. The DTV channel selector 1008 selects a specific DTV channel under the control of the processor 1014 and down-converts the selected channel signal from UHF (ultra high frequency) to IF (intermediate frequency) by a conventional method. An amplifier (AMP) 1010 amplifies the selected IF channel signal. This amplifier employs automatic gain control (AGC) to improve the dynamic distance of the configuration. The analog-to-digital converter and sampler (A / D) 1012 generates digital samples of the DTV channel signal s _samp (t) and passes these samples to the DSP 1014.

Now, the processing of the DTV channel signal by the DSP 1014 is described for an incoherent software receiver. A slight offset frequency for the down-converted and sampled signal is assumed. If this signal is downconverted to baseband, the slight offset is 0 Hz. A complete autocorrelation function is generated based on the signal s _samp (t) sampled by the processing. There are many techniques for performing the process more efficiently, such as using a low load time ratio reference signal. Let T _i be the sampled data period, ω _{in be} the slight offset of the sampled incident signal, and ω _offset be the largest possible offset frequency. This is due to Doppler shift and oscillator frequency drift. The process implements the following pseudo code.

・ R _max = 0
Create a composite code signal
s _code (t) = C _i (t) + jC _q (t)
Here, C _i is a function representing an in-phase baseband signal, and C _q is a function representing a quadrature baseband signal.
・ F (s _code ) ^* is calculated. Here, F is a Fourier transform operator and * is a conjugate operator.
・ From ω = ω _in −ω _offset to ω _in + ω _offset every π / 2T _i・ Create a composite mixing signal.
s _mix (t) = cos (ωt) + jsin (ωt), t = [0… T _i ]
-Synthesize the incident signal s (t) and the mixing signal s _mix (t).
s _comb (t) = s _samp (t) s _mix (t)
Calculate the correlation function.
R (τ) = F ⁻¹ {F (s _code ) ^* F (s _comb )}
・ When max _τ | R (τ) |> R _max , R _max ← max _τ | R (τ) |, R _store (τ) = R (τ)
・ Next ω

On the exit from processing, R _store (τ) stores the correlation between the incident sampled signal s _samp (t) and the composite code signal s _code (t). R _store (τ) can be further improved by searching over a smaller step ω. The size of the first step for ω must be less than half the Nyquist rate 2π / T _i. The time offset τ that produces the maximum correlation output is used as the pseudorange.

Alternative Embodiments The present invention can be implemented in digital electronic circuitry, or computer hardware, firmware, software, or a combination thereof. The apparatus of the present invention can be implemented in a computer program product that is explicitly embodied in a machine readable storage device for execution by a programmable processor. The method steps of the present invention may be implemented by a programmable processor that executes a program of instructions, and performs the functions of the present invention by manipulating input data to produce output. The present invention can be advantageously executed in one or more computer programs, can be executed in a programmable system including at least one connected programmable processor, and includes a data storage system and at least one input device. And receiving data and instructions from at least one output device and transmitting the data and instructions to the data storage system, at least one input device and at least one output device. Each computer program can be executed in a high level procedural or object oriented programming language, or assembly or machine language if desired. In any case, the language can be a translated or interpreted language. Suitable processors include, by way of example, both general and special purpose microprocessors. Generally, a processor will receive instructions and instructions from a read-only memory and / or a random access memory. Generally, a computer includes one or more mass storage devices for storing data files, and the device includes a magnetic disk such as an internal hard disk or a removable disk, a magneto-optical disk, and an optical disk. Storage devices suitable for unambiguously embodying computer program instructions and data include all forms of non-volatile memory, such as semiconductor memory devices such as EPROM, EEPROM, flash memory devices, internal hard disks, removable disks, etc. Magnetic disk, magneto-optical disk, and CD-ROM disk. Some of the foregoing are supplemented by or cited by ASICs (Application Specific Integrated Circuits).

  A number of aspects of the invention have been described. However, it will be understood that various modifications may be made without departing from the spirit and scope of the invention.

  For example, while a method for tracking ISDB-T signals has been described, there is a method for tracking these signals by using various types of matched filters using various types of conventional delay locked loops. It is clear that there are several.

  While embodiments of the present invention are discussed with reference to an 8 MHz signal, the embodiments can be used with other bandwidth signals. Furthermore, embodiments of the present invention can use a portion of the bandwidth of the ISDB-T signal. For example, embodiments of the present invention can achieve satisfactory results using only 6 MHz of an 8 MHz ISDB-T signal. Embodiments of the present invention can be extended to use future increases to the ISDB-T signal.

  Embodiments of the invention take advantage of the fact that DTV signals have high power and can be further tracked by capturing a burst of signals and using a low load time rate reference signal. The signal does not use all incident signal energy. For example, one embodiment uses a time-gated delay-locked loop (DLL), eg, “Digital Communications by Satellite” by JJ Spillker Jr. Prentice Hall, Inglewood Cliff, New Jersey (1977) 18-6. And the like. Other embodiments use other variations of DLLs, including coherent, incoherent, and quasi-coherent DLLs. For example, "Digital Communications by Satellite" by JJ Spielcar Jr. Prentice Hall, Inglewood Cliff, New Jersey (1977) Chapter 18 and "Global Positioning System-Theory by B Parkinson and J Spircar Jr. And applications "AIAA, Washington, DC (1996), Vol. 1, Chapter 17 and" Basics of Signal Tracking Theory "by J. Spielker Jr. Other embodiments use various types of matching filters, such as a recirculating matching filter.

  In some embodiments, the DTV location information server 110 uses redundant signals available at the system level, eg, pseudoranges available from the DTV transmitter, and further checks each DTV channel and pseudorange. And identify the pseudorange of the erroneous DTV channel. One such technique is conventional receiver automatic integrity monitoring (RAIM).

  Another form of the invention can combine the above DTV distance signal with other types of signals and calculate the pseudorange. For example, combining and using DTV and GPS satellite signals is described in US Patent Application No. 10/159478, filed May 31, 2002 by Matthew Rabinowitz and James J. Spielker "Positioning with augmented GPS", the subject matter of which is hereby incorporated by reference. Further, the DTV signal can be combined with the mobile base station signal or digital radio signal, or any other signal that includes a synchronization code for the combined position solution.

  Furthermore, other forms are within the scope of the claims.

1 illustrates one embodiment of the present invention. The process of an Example is shown. Figure 2 shows a location determination configuration using three DTV transmitters. Fig. 4 shows an embodiment of a receiver used to generate pseudorange measurements. A simplified example of user terminal location calculation is shown. Fig. 4 shows the effect of one mound on a constant distance circle for a DTV transmitter located at the same altitude as the surrounding land. Shown are several distributed pilots that transmit all at once. The coherent autocorrelation function is shown. An embodiment of a monitoring device will be shown. An embodiment of a software receiver is shown.

Claims (87)

  A digital television (DTV) broadcast signal comprising a terrestrial digital integrated broadcast service (ISDB-T) signal is received at a user terminal from a DTV transmitter, and the DTV based on the user terminal and a known component of the broadcast DTV signal A user terminal position determination method comprising: determining a pseudo distance to a transmitter, and determining a position of the user terminal based on the pseudo distance and a position of the DTV transmitter.   The positioning of the user terminal adjusts the pseudorange based on a difference between a transmitter clock at the DTV transmitter and a known time reference, and the adjusted pseudorange and the DTV transmitter The method of claim 1, comprising determining the position of the user terminal based on a position.   The method of claim 1, wherein the known component is a distributed pilot carrier.   The position determination of the user terminal determines an offset between a local time reference and a master time reference at the user terminal, and the user terminal is based on the pseudorange, the position of the DTV transmitter, and the offset. The method of claim 1, comprising determining the location of a terminal.   5. The method of claim 4, further comprising determining a continuous location of the user terminal using the offset.   The pseudorange determination comprises storing a portion of the DTV signal and obtaining the pseudorange by continuously correlating the stored portion with a signal generated by the user terminal. the method of.   The method of claim 1, wherein determining the pseudorange comprises correlating the DTV signal with a signal generated by the user terminal while obtaining the pseudorange when the DTV signal is received.   The position determination of the user terminal comprises determining a general geographical area in which the user terminal is located, and determining the position of the user terminal based on the pseudorange and the general geographical area. The method described.   The method according to claim 8, wherein the general geographical area is a radio wave coverage of another transmitter communicatively connected to the user terminal.   The position of the user terminal determines a tropospheric propagation speed in the vicinity of the user terminal, adjusts the pseudorange based on the tropospheric propagation speed, and is based on the adjusted pseudorange and the position of the DTV transmitter. The method of claim 1, further comprising: determining the position of the user terminal.   The determination of the position of the user terminal adjusts the pseudo distance based on the altitude of the terrain near the user terminal, and determines the position of the user terminal based on the adjusted pseudo distance and the position of the DTV transmitter. The method of claim 1, comprising determining the position.   And selecting the DTV signal from a plurality of DTV signals based on the identity of another transmitter communicatively connected to the user terminal and a storage table correlating the other transmitter with the DTV signal. The method of claim 1 comprising:   The method of claim 1, further comprising receiving location information input from a user and selecting the DTV signal from a plurality of DTV signals based on the location information input.   Further, based on a storage table that scans available DTV signals to collect the fingerprints of the positions, selects the DTV signals to be used and matches the fingerprints with known fingerprints against known positions. The method of claim 1, further comprising: determining the pseudorange from the available DTV signal.   The method of claim 1, further comprising ascertaining the integrity of the pseudorange based on redundant pseudoranges from the DTV transmitter using receiver automatic integrity monitoring (RAIM).   European Television Standards Institute (ETSI) Digital Video Broadcasting—A digital television (DTV) broadcast signal comprising a terrestrial (ISDB-T) signal is received from a DTV transmitter at the user terminal, and based on the user terminal and the DTV broadcast signal Determining a pseudo distance to the DTV transmitter and transmitting the pseudo distance to a location information server configured to determine the position of the user terminal based on the pseudo distance and the position of the DTV transmitter. A user terminal location determination method comprising:   The pseudo distance is determined by determining the transmission time of the known component of the DTV broadcast signal from the DTV transmitter, determining the reception time of the known component at the user terminal, and determining the transmission time and the reception time. The method of claim 16, comprising determining a difference between.   The method of claim 16, wherein the known component is a distributed pilot carrier.   17. The pseudorange determination comprises storing a portion of the DTV signal and continuously correlating the stored portion with a signal generated by the user terminal to obtain the pseudorange. Method.   The method of claim 16, wherein determining the pseudorange comprises correlating the DTV signal with a signal generated by the user terminal while receiving the DTV signal and obtaining the pseudorange.   A pseudorange determined between the user terminal and a DTV transmitter based on a DTV signal broadcast by the DTV transmitter is received from the user terminal, wherein the DTV signal is received from the European Telecommunications Standards Institute (ETSI) digital video. The pseudo-range is determined based on a known component of the ISDB-T signal, and the user terminal based on the pseudo-range and the position of the DTV transmitter. A method for determining a position of a user terminal comprising determining a position.   The positioning of the user terminal adjusts the pseudorange based on a difference between a transmitter clock at the DTV transmitter and a known time reference, and the adjusted pseudorange and the DTV transmitter The method of claim 21, wherein the position of the user terminal is determined based on a position.   The method of claim 21, wherein the known component is a distributed pilot carrier.   The position determination of the user terminal determines an offset between a local time reference and a master time reference of the user terminal, and based on the pseudorange, the position of the DTV transmitter, and the offset of the user terminal The method of claim 21, comprising determining the position.   The method of claim 24, further comprising determining a continuous position of the user terminal using the offset.   The position determination of the user terminal comprises determining a general geographical area in which the user terminal is located, and determining the position of the user terminal based on the pseudorange and the general geographical area. The method described.   27. The method of claim 26, wherein the general geographic area is a radio wave coverage of another transmitter that is communicatively connected to the user terminal.   The position determination of the user terminal determines a tropospheric propagation velocity in the vicinity of the user terminal, adjusts the pseudorange based on the tropospheric propagation velocity, and adjusts the adjusted pseudorange and the position of the DTV transmitter. The method of claim 21, comprising determining the position of the user terminal based on:   The position determination of the user terminal adjusts the pseudo distance based on the altitude of the terrain in the vicinity of the user terminal, and the user terminal based on the adjusted pseudo distance and the position of the DTV transmitter. The method of claim 21, comprising determining a position.   European Telecommunications Standards Institute (ETSI) Digital Video Broadcasting-means for receiving a digital television (DTV) broadcast signal comprising a terrestrial (ISDB-T) signal from a DTV transmitter at a user terminal, the user terminal and the DTV broadcast signal A user terminal comprising: means for determining a pseudorange with the DTV transmitter based on a known component; and means for determining the position of the user terminal based on the pseudorange and the position of the DTV transmitter Positioning device.   The means for determining the position includes means for adjusting the pseudorange based on a difference between a transmitter clock at the DTV transmitter and a known time reference, the adjusted pseudorange and the DTV transmitter 32. The apparatus of claim 30, comprising: means for determining the position of the user terminal based on the position.   32. The apparatus of claim 31, wherein the known component is a distributed pilot carrier.   The means for determining the position of the user terminal is based on means for determining an offset between a local time reference and a master time reference of the user terminal, the pseudorange, the position of the DTV transmitter, and the offset. 31. The apparatus of claim 30, further comprising means for determining the position of the user terminal.   34. The apparatus of claim 33, further comprising means for determining a continuous position of the user terminal using the offset.   The means for determining pseudoranges comprises means for storing a portion of the DTV signal and means for continuously correlating the stored portion with a signal generated by the user terminal to obtain the pseudorange. The apparatus of claim 30.   31. The apparatus of claim 30, wherein the means for determining a pseudorange comprises means for receiving the DTV signal and correlating the DTV signal with a signal generated by the user terminal while obtaining the pseudorange.   The means for determining the position of the user terminal includes means for determining a general geographical area in which the user terminal is located, and means for determining the position of the user terminal based on the pseudorange and the general geographical area. 32. The apparatus of claim 30, comprising:   38. The apparatus of claim 37, wherein the general geographical area is a radio wave reach of another transmitter that is communicably connected to the user terminal.   The means for determining the position of the user terminal comprises: means for determining a tropospheric propagation speed in the vicinity of the user terminal; means for adjusting the pseudo distance based on the tropospheric propagation speed; and the adjusted pseudo distance 32. The apparatus of claim 30, comprising: means for determining the position of the user terminal based on the position of the DTV transmitter.   The means for determining the position of the user terminal is based on means for adjusting each pseudo distance based on the altitude of the terrain in the vicinity of the user terminal, the adjusted pseudo distance and the position of the DTV transmitter. 31. The apparatus of claim 30, further comprising means for determining the position of the user terminal.   Further, the DTV signal is selected from a plurality of DTV signals based on an identity of another transmitter communicatively connected to the user terminal and a storage table that correlates the other transmitter and the DTV signal. 32. The apparatus of claim 30, comprising means.   The apparatus of claim 30, further comprising means for receiving position information input from a user and means for selecting the DTV signal from a plurality of DTV signals based on the position information input.   Further, the available DTV signal based on means for scanning the available DTV signal to collect a fingerprint of the location information and a storage table that matches the fingerprint and the known fingerprint against a known location. 31. The apparatus of claim 30, further comprising: means for selecting the DTV broadcast signal used to determine the pseudorange from the.   31. The apparatus of claim 30, further comprising means for ascertaining the integrity of the pseudorange based on redundant pseudoranges from the DTV transmitter using receiver automatic integrity monitoring (RAIM).   European Telecommunications Standards Institute (ETSI) Digital Video Broadcasting-means for receiving a digital television (DTV) broadcast signal comprising a terrestrial (ISDB-T) signal from a DTV transmitter at the user terminal, the user terminal and the DTV broadcast signal Means for determining a pseudo-range between said DTV transmitter based on a known component of; and a position configured to determine the position of said user terminal based on said pseudo-range and the position of said DTV transmitter An apparatus for determining the position of a user terminal comprising means for transmitting the pseudorange to an information server.   The means for determining the pseudorange includes means for determining a transmission time of the component of the DTV broadcast signal from the DTV transmitter, means for determining a reception time of the component at the user terminal, and the transmission time; 46. The apparatus of claim 45, comprising: means for determining the difference between the reception times.   46. The apparatus of claim 45, wherein the component is a distributed pilot carrier.   The means for determining a pseudorange comprises means for storing a portion of the DTV signal and means for continuously correlating the stored portion and a signal generated by the user terminal to obtain the pseudorange. 46. The apparatus of claim 45, comprising.   46. The apparatus of claim 45, wherein the means for determining a pseudorange comprises means for receiving the DTV signal and correlating the DTV signal with a signal generated by the user terminal while obtaining the pseudorange.   A pseudorange is received from a user terminal, and the pseudorange is determined between the user terminal and a DTV transmitter based on a DTV signal broadcast by the DTV transmitter, the DTV signal ETSI) digital video broadcast-terrestrial (ISDB-T) signal, wherein the pseudorange is determined based on known components of the DTV signal, based on the pseudorange and the position of the DTV transmitter And a means for determining the position of the user terminal.   The means for determining the position of the user terminal comprises: means for adjusting the pseudorange based on a difference between a transmitter clock at the DTV transmitter and a known time reference; and the adjusted pseudorange. 51. The apparatus of claim 50, comprising: means for determining the position of the user terminal based on the position of the DTV transmitter.   51. The apparatus of claim 50, wherein the known component is a distributed pilot carrier.   The means for determining the position of the user terminal includes means for determining an offset between a local time reference and a master time reference of the user terminal, the pseudorange, the position of the DTV transmitter, and the offset. 51. The apparatus of claim 50, comprising: means for determining the position of the user terminal based on.   54. The apparatus of claim 53, further comprising means for determining a continuous location of the user terminal using the offset.   The means for determining the position of the user terminal determines the position of the user terminal based on means for determining a general geographical area in which the user terminal is located, the pseudorange and the general geographical area. 51. The apparatus of claim 50, comprising: means.   56. The apparatus of claim 55, wherein the general geographical area is a radio wave reach of another transmitter that is communicatively connected to the user terminal.   The means for determining the position of the user terminal comprises: means for determining a tropospheric propagation velocity near the user terminal; means for adjusting the pseudorange based on the tropospheric propagation velocity; the adjusted pseudorange; 51. The apparatus of claim 50, comprising: means for determining the position of the user terminal based on the position of a DTV transmitter.   The means for determining the position of the user terminal is based on means for adjusting the pseudorange based on the altitude of the terrain near the user terminal, based on the adjusted pseudorange and the position of the DTV transmitter. 51. The apparatus of claim 50, further comprising means for determining the location of the user terminal.   A digital television (DTV) broadcast signal, which is stored in a computer-readable medium and is composed of the European Telecommunications Standards Institute (ETSI) digital video broadcast-terrestrial (ISDB-T) signal, is received from the DTV transmitter at the user terminal. Determining a pseudo distance between the user terminal and the DTV transmitter based on a known component of the DTV broadcast signal, and determining the position of the user terminal based on the pseudo distance and the position of the DTV transmitter. A computer program product for user terminal location determination comprising instructions executable to cause a programmable processor to determine.   The executable instructions that cause a programmable processor to determine the location of the user terminal are adjusted by adjusting the pseudorange based on a difference between a transmitter clock at the DTV transmitter and a known time reference. 60. The computer program product of claim 59, further comprising executable instructions that cause a programmable processor to determine the position of the user terminal based on the pseudorange and the position of the DTV transmitter.   60. The computer program product of claim 59, wherein the known component is a distributed pilot carrier.   The executable instructions that cause a programmable processor to determine the position of the user terminal determine an offset between the local time reference of the user terminal and a master time reference, and the pseudorange and the position of the DTV transmitter. 60. The computer program product of claim 59, comprising executable instructions that cause a programmable processor to determine the location of the user terminal based on the offset and the offset.   64. The computer program product of claim 62, further comprising executable instructions that cause a programmable processor to determine a continuous location of the user terminal using the offset.   The executable instructions that cause a programmable processor to determine a pseudorange store a portion of the DTV signal and continuously correlate the stored portion with a signal generated at the user terminal to generate the pseudorange. 60. The computer program product of claim 59, comprising executable instructions that cause a programmable processor to obtain   The executable instructions for causing the programmable processor to determine the pseudorange are to allow the programmable processor to correlate the DTV signal with the signal generated by the user terminal while receiving the DTV signal and obtaining the pseudorange. 60. The computer program product of claim 59, comprising executable instructions to be performed.   The executable instructions that cause a programmable processor to determine the location of the user terminal determine a general geographic area in which the user terminal is located, and based on the pseudorange and the general geographic area, 60. The computer program product of claim 59, comprising executable instructions that cause a programmable processor to determine the location.   67. The computer program product of claim 66, wherein the general geographic area is a radio wave reach of another transmitter communicatively connected to the user terminal.   The instructions executable to cause a programmable processor to determine the position of the user terminal cause the programmable processor to determine a tropospheric propagation velocity in the vicinity of the user terminal and adjust the pseudorange based on the tropospheric propagation velocity. 60. The computer program product of claim 59, comprising instructions capable of causing the location of the user terminal to be determined based on the adjusted pseudorange and the location of the DTV transmitter.   The executable instructions that cause a programmable processor to determine the position of the user terminal adjust the pseudorange based on the altitude of the terrain near the user terminal, and adjust the pseudorange and the DTV transmitter 60. The computer program product of claim 59, comprising executable instructions that cause a programmable processor to determine the position of the user terminal based on the position of the user terminal.   And selecting the DTV signal from a plurality of DTV signals based on an identity of another transmitter communicatively connected to the user terminal and a storage table correlating the other transmitter with the DTV signal. 60. The computer program product of claim 59, comprising executable instructions for causing a programmable processor to perform.   60. The computer program of claim 59, further comprising executable instructions for receiving location information input from a user and causing a programmable processor to select the DTV signal from a plurality of DTV signals based on the location information input. Product.   Further, the available DTV signal is scanned to collect the fingerprint of the position, and the pseudo D from the available DTV signal based on the fingerprint and a storage table that matches the known fingerprint with a known position. 60. The computer program product of claim 59, comprising executable instructions that cause a programmable processor to select the DTV broadcast signal used to determine distance.   And further comprising executable instructions for causing a programmable processor to verify the integrity of the pseudorange based on redundant pseudoranges from the DTV transmitter using receiver automatic integrity monitoring (RAIM). Item 60. The computer program product according to Item 59.   A digital television (DTV) broadcast signal, which is stored in a computer-readable medium and is composed of the European Telecommunications Standards Institute (ETSI) digital video broadcast-terrestrial (ISDB-T) signal, is received from the DTV transmitter at the user terminal. Determining a pseudo distance between the user terminal and the DTV transmitter based on a known component of the DTV broadcast signal, and determining the position of the user terminal based on the pseudo distance and the position of the DTV transmitter. A computer program product for user terminal location determination comprising executable instructions for causing a programmable processor to send the pseudorange to a location information server configured to determine.   An executable instruction that causes the programmable processor to determine the pseudorange determines a transmission time of the component of the DTV broadcast signal from the DTV transmitter, determines a reception time of the component at the user terminal, and transmits the transmission 75. The computer program product of claim 74, comprising executable instructions that cause a programmable processor to determine a difference between time and the reception time.   75. The computer program product of claim 74, wherein the component is a distributed pilot carrier.   The executable instructions that cause a programmable processor to determine a pseudorange store a portion of the DTV signal and continuously correlate the stored portion with the signal generated by the user terminal to generate the pseudorange. 75. The computer program product of claim 74, comprising executable instructions that cause a programmable processor to obtain the data.   The executable instructions for causing the programmable processor to determine the pseudorange are to allow the programmable processor to correlate the DTV signal with the signal generated by the user terminal while receiving the DTV signal and obtaining the pseudorange. 75. The computer program product of claim 74, comprising executable instructions to be performed.   Reliably stored in a computer readable medium to receive a pseudorange from a user terminal, the pseudorange determined between the user terminal and the DTV transmitter based on a DTV signal broadcast by a DTV transmitter Here, the DTV signal is composed of an ETSI digital video broadcast-terrestrial (ISDB-T) signal, and the pseudorange is determined based on a known component of the DTV signal. A computer program product for user terminal position determination comprising executable instructions for causing a programmable processor to determine the position of the user terminal based on the pseudorange and the position of the DTV transmitter.   The executable instructions that cause a programmable processor to determine the location of the user terminal are adjusted by adjusting the pseudorange based on a difference between a transmitter clock at the DTV transmitter and a known time reference. 80. The computer program product of claim 79, further comprising executable instructions that cause a programmable processor to determine the position of the user terminal based on the pseudorange and the position of the DTV transmitter.   80. The computer program product of claim 79, wherein the known component is a distributed pilot carrier.   The executable instructions that cause a programmable processor to determine the location of the user terminal determine an offset between a local time reference and a master time reference at the user terminal, and the pseudorange and the DTV transmitter 80. The computer program product of claim 79, comprising executable instructions that cause a programmable processor to determine the position of the user terminal based on a position and the offset.   The computer program product of claim 82, further comprising executable instructions that cause a programmable processor to determine a continuous location of the user terminal using the offset.   The executable instructions that cause a programmable processor to determine the location of the user terminal determine a general geographic area in which the user terminal is located, and based on the pseudorange and the general geographic area, 80. The computer program product of claim 79, comprising executable instructions that cause a programmable processor to determine the location.   85. The computer program product of claim 84, wherein the general geographic area is a radio wave reach of another transmitter communicatively connected to the user terminal.   The executable instructions that cause a programmable processor to determine the location of the user terminal determine a tropospheric propagation velocity in the vicinity of the user terminal, adjust the pseudorange based on the tropospheric propagation velocity, and adjust the simulated pseudo 80. The computer program product of claim 79, comprising executable instructions that cause a programmable processor to determine the position of the user terminal based on distance and the position of the DTV transmitter.   The executable instructions for causing a programmable processor to determine the position of the user terminal adjust the pseudorange based on the altitude of the terrain in the vicinity of the user terminal, and the adjusted pseudorange and the DTV transmitter 80. The computer program product of claim 79, comprising executable instructions that cause a programmable processor to determine the location of the user terminal based on the location of the computer.

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