United States Patent
`L00mis et al.
`
`[191
`
`[541
`
`[751
`
`[731
`
`PORTABLE HYBRID LOCATION
`DETERMINATION SYSTEM
`
`Inventors; Peter Van Wyck Loomis, Sunnyvale;
`James M. Janky, Los Altos; John F.
`SChiPPeI‘, P2110 AlIO, all Of Calif
`_
`_
`_
`_
`_
`_
`Asslgnee: Tumble Navlgatlon Llmlted’
`Sunnyvale’ Cahf'
`
`Appl' NO‘: 08/806’549
`Filed:
`Feb. 25, 1997
`
`Related US. Application Data
`
`Continuation of application No. 08/191,984, Feb. 4, 1994,
`abandoned.
`
`IIlt. Cl-6 ............................... ..
`US. Cl. ......................... .. 342/357; 342/463; 342/457
`Field of Search ................................... .. 342/357, 457,
`342/463, 464, 465
`
`References Cited
`
`U'S' PATENT DOCUMENTS
`6/1970 Komen et a1. _
`3,518,376
`6/1975 Fletcher .
`3,889,264
`4,054,880 10/1977 Dalabakis et al--
`4,459,667
`7/1984 Takeuchi ............................... .. 342/389
`4,646,290
`2/1987 Hlns_ ' ' ' ' ' '
`' ' ' ' " 370/84
`4’651’156
`3/1987 Mamnez """ "
`" 342/457
`4,660,193
`4/1987 Young et a1. .
`370/11
`477827531 11/1988 Kan et at‘ _ _ _ _ _ _ _ _
`_ _ _ n 381/14
`4,799,062
`1/1989 sanderford et at
`342/45O
`4,806,940
`2/1989 Hanal et at __
`__ 342/451
`
`US005936572A
`Patent Number:
`Date of Patent:
`
`[111
`[451
`
`5,936,572
`Aug. 10, 1999
`
`OTHER PUBLICATIONS
`
`Loran—C User Handbook, Dept. of Transportation, US.
`Coast Guard, Commandant Instruction M16562.3, May
`1990
`Tom Logsdon, The NAVSIAR Global Positioning System,
`Van Nostrand Reinhold, 1992, pp. 17—90.
`R.G. BroWn, Introduction to Random Signal Analysis and
`Kalman Filtering, Wiley and Sons, 1983, pp. 181—272.
`Mark SturZa, “Navi ation S stem Inte rit
`Monitorin
`Using Redundant NTeasuremZnts”, Navigation, vol. 35
`(1988—1989),PP- 483—501
`
`Primary Examiner—Gregory C. Issing
`Attorney, Agent, or Firm—John Schipper
`
`[57]
`
`ABSTRACT
`
`Apparatus and method for determining the present location
`of a mobile user that carries the apparatus inside or outside
`buildings and structures Within a region R. The apparatus
`includes a radio location determination (LD) signal module
`that receives radioWaves from at least three radio LD signal
`sources, such as FM carrier or subcarrier signals, and an
`outdoor LD signal module that receives outdoor LD signals
`from at three other satellite-based or ground-based outdoor
`LD signal sources, such as GPS, GLONASS or Loran-C
`signal sources. The radio LD signals and outdoor LD signals
`are used to (1) determine the location of the radio LD
`module, (2) determine the location of the OutdOOr LD
`module and (3) determine an indicium representing signal
`strength or signal quality for the radio LD signals and for the
`.
`.
`.
`.
`.
`.
`outdoor LD signals. The radio LD signal indicium and the
`outdoor LD signal indicium are compared With threshold
`values for these indicia, and at most one of the radio LD
`
`_ _ _ _ __ 329/50
`3/1989 Ma _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
`4,816,769
`.. 342/125
`4/1990 Ichiyoshi
`4,914,735
`- - - - -- 455/45
`6/1991 Wheeless - - - - - -
`5,023,934
`9/1991 Duffet-Smith ........................ .. 342/457
`5,045,861
`5,073,784 12/1991 Westfall ................................ .. 342/465
`
`module location and the outdoor LD module location is
`selected as the present location of the apparatus user. The
`radio LD module and the outdoor LD module can be
`Combined in a hybrid portable LD System, or the tW0
`modules can be Separated from and move independently of
`
`5,170,487 12/1992 Peek . . . . . . . . . .
`
`5,173,710 12/1992 Kelley et a1
`
`. . . . .. 455/45
`
`342/463
`
`each when
`
`5,193,213
`
`3/1993 Chon . . . . . . . . .
`
`. . . . .. 455/45
`
`5,235,632
`
`8/1993 Raith ....................................... .. 379/59
`
`18 Claims, 8 Drawing Sheets
`
`/71
`W
`
`73
`
`91
`
`Radio LD
`Receiver/Processor 1* Controller
`
`75
`
`83
`
`s1\
`\|-)/
`
`/11
`85
`bJ/87
`Outdoor LD
`Receiver/Processor
`
`95
`
`97
`
`Display
`
`93
`
`99
`
`Cellular bk 103
`
`101
`
`Radio 5K
`
`107
`
`105
`
`T-Mobile / TCS / Ericsson EXHIBIT 1008
`T-Mobile / TCS / Ericsson v. TracBeam
`Page 1
`
`

`
`U.S. Patent
`
`Aug. 10,1999
`
`Sheet 1 of8
`
`5,936,572
`
`In
`(\1
`
`Central
`
`T-Mobile / TCS / Ericsson EXHIBIT 1008
`T-Mobile / TCS / Ericsson v. TracBeam
`Page 2
`
`

`
`U.S. Patent
`
`Aug. 10,1999
`
`Sheet 2 of8
`
`5,936,572
`
`N55? 3
`
`N55? 0%
`
`8
`
`\hocosvmi
`
`m .05
`
`N55- a
`
`@m
`
`8538mm
`aim E
`
`T-Mobile / TCS / Ericsson EXHIBIT 1008
`T-Mobile / TCS / Ericsson v. TracBeam
`Page 3
`
`

`
`U.S. Patent
`
`Aug. 10,1999
`
`Sheet 3 of8
`
`5,936,572
`
`bm
`
`m .95
`
`am
`
`8:50
`
`T-Mobile / TCS / Ericsson EXHIBIT 1008
`T-Mobile / TCS / Ericsson v. TracBeam
`Page 4
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`

`
`U.S. Patent
`
`Aug. 10,1999
`
`Sheet 4 of8
`
`5,936,572
`
`FIG. 4
`
`29
`
`
`
`Central /
`
`T-Mobile / TCS / Ericsson EXHIBIT 1008
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`Page 5
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`

`
`U.S. Patent
`
`Aug. 10,1999
`
`Sheet 5 of8
`
`5,936,572
`
`Xq 8
`
`56
`
`55,59
`
`29
`
`FIG. 5
`
`Central
`
`T-Mobile / TCS / Ericsson EXHIBIT 1008
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`

`
`U.S. Patent
`
`Aug. 10, 1999
`
`Sheet 6 of 8
`
`5,936,572
`
`73
`
`W
`
`75
`
`91
`
`/
`/
`
`83
`
`Y/ 85
`y 87
`
`Radio LD
`_
`-
`Outdoor LD
`Receiver/Processor _——‘ Controller —_ Receiver/Processor
`
`95
`
`97
`
`Display
`
`93
`
`99
`
`Cellular bk 103
`
`101
`
`Radio bk
`
`107
`
`105
`
`111\\Ij/13 FIG. 6
`
`131
`\'J/
`
`31
`
`133
`
`135
`51/
`
`Controller
`
`- — — — — — — - Receiver/Processor/
`
`Radio LD
`Receiver/Processor/ \1 13
`Transmitter
`I
`Display/
`Storage
`
`Outdoor LD
`\ Transmitter
`137
`
`1 15
`
`Cellular
`
`Radio
`
`121
`
`119
`
`125
`
`123
`
`FIG. 7
`
`T-Mobile / TCS / Ericsson EXHIBIT 1008
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`Page 7
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`

`
`U.S. Patent
`
`Aug. 10,1999
`1
`
`Sheet 7 of8
`
`5,936,572
`
`151
`
`153
`
`155
`/
`
`157
`
`Activate LD System
`
`Radio LD Signal Sources
`Transmit Signals
`
`‘
`Radio LD Signals Are Received By
`Radio LD Unit And Outdoor LD Unit
`
`1
`
`Outdoor LD Unit Determines Relative
`Phases Of Radio LD Signals And
`Provides Relative Phase Information And
`Signal Parameter(s) For Radio LD Unit
`
`159
`
`165
`
`Radio LD Signals
`Adequate To Determine Location
`Of Radio LD Unit
`?
`
`.
`
`.
`
`N
`
`0
`
`LD system Advises User
`That Radio LD Unit
`Cannot Provide Adequate
`Signals For LD Process
`(Optional)
`
`161
`
`163
`
`Radio LD Unit Receives Relative
`Phase Information and Determines
`Location Of Radio LD Unit
`
`LD System Processes, Transmits,
`Stores And/Or Displays Its Location
`(Optional)
`
`FIG. 8
`
`T-Mobile / TCS / Ericsson EXHIBIT 1008
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`Page 8
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`

`
`U.S. Patent
`
`Aug. 10, 1999
`
`Sheet 8 0f 8
`
`5,936,572
`
`1
`
`171
`
`Activate LD System
`
`Radio LD And Outdoor LD Signal
`Sources Transmit Signals
`
`Radio LD and Outdoor LD Signals
`Are Received By
`Radio LD Unit And Outdoor LD Unit
`
`Outdoor LD Unit Determines Its Location
`And Relative Phases Of Radio LD Signals
`And Provides Relative Phase Information,
`Its Own Location And Signal Indicater
`For the Radio LD Unit
`
`173
`
`175
`
`177
`
`189
`
`179
`
`Neither
`
`LD System Advises User
`That Neither Unit
`Can Provide Adequate
`Signals For LD Process
`(Optional)
`
`LD Unit, If Any,
`Should Provide
`LD System Location
`Information
`
`181
`
`Outdoor
`
`Unit
`
`Use Outdoor LD Unit
`To Provide
`LD System Location
`
`183
`
`185
`
`187
`
`Radio LD Unit
`
`Use Radio LD Unit To Provide
`LD System Location
`
`A
`
`Selected LD Unit Determines
`Location Of LD System
`
`LD System Processes, Transmits,
`Stores And/Or Displays Its Location
`(Optional)
`
`FIG. 9
`
`T-Mobile / TCS / Ericsson EXHIBIT 1008
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`Page 9
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`

`
`1
`PORTABLE HYBRID LOCATION
`DETERMINATION SYSTEM
`
`5,936,572
`
`This patent application is a continuation of the patent
`application entitled “Portable Hybrid Location Determina
`tion System”, US. Ser. No. 08/191,984, ?led on Feb. 4,
`1994, abandoned, and assigned to the assignee of this patent
`application.
`
`FIELD OF THE INVENTION
`
`This invention relates to use of tWo or more location
`determination systems, Where one of these systems may use
`radio carrier or subcarrier Waves, to determine the location
`of a mobile user of the systems.
`
`BACKGROUND OF THE INVENTION
`In recent years, several individual location determination
`systems have been proposed and applied to provide esti
`mates of varying accuracy for location of an object in special
`circumstances. For an object located outdoors and aWay
`from obstructions such as groups of buildings, a satellite
`based LD system such as the Global Positioning System
`(GPS) or the Global Orbiting Navigation Satellite System
`(GLONASS) or other similar system can be used to provide
`location estimates With associated inaccuracies as loW as ten
`meters or less. A ground-based system, such as Loran,
`Omega, Tacan, Decca, JTIDS Relnav or PLRS, can provide
`location estimates With associated inaccuracies as loW as 60
`meters or less in the same situations, using triangulation
`based on intersections of hyperbolic surfaces. These systems
`provide object location estimates over regions With diam
`eters of hundreds of kilometers (km) but do not Work Well
`Where some of the signal sources are obscured by structures
`outdoors, or When the object to be located is positioned
`indoors.
`Some cellular telephone-based systems also provide esti
`mates of location, using comparison of signal strengths from
`three or more sources. FM subcarrier signals can be used
`over smaller regions to estimate the location of an object
`inside or outside a building or other structure, even Where
`the signal sources have no line-of-sight to the object. Use of
`cellular-based systems and FM subcarrier systems for loca
`tion determination tends to be limited to smaller regions,.
`With diameters of the order of 20—50 km.
`FM subcarrier signals and AM carrier signals have been
`used for some types of radio Wave communications. In US.
`Pat. No. 3,889,264, Fletcher discloses a vehicle location
`system in Which the unsynchroniZed AM carrier signals
`from three or more AM radio stations form hyperbolic
`isophase grid lines that are used to determine location of a
`vehicle. The vehicle must be equipped With a three-channel,
`tunable receiver, and its location must be referenced to an
`initial knoWn location by counting the number of isophase
`lines crossed after the vehicle leaves the initial location.
`Isophase drift is compensated for by subtraction from the
`count.
`Dalabakis et al, in US. Pat. No. 4,054,880, disclose a
`radio navigation and vehicle location system employing
`three loW frequency subcarrier signals received from three
`radio stations at a three-channel, tunable receiver located on
`the vehicle. Isophase lines crossed are counted after the
`vehicle leaves an initial knoWn location. This system, like
`the Fletcher system, is a delta-position system that deter
`mines vehicle location only relative to an initially knoWn
`location.
`US. Pat. No. 4,646,290, issued to Hills, discloses use of
`F.C.C.-approved Subsidiary Communication AuthoriZation
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`2
`(SCA) FM subcarrier signals for one Way transmission. This
`patent discloses transmission of a plurality of messages,
`Which may be delivered to the transmitter at a Wide range of
`bit rates, to be transmitted at a single bit rate that is at least
`as large as the highest bit rate for message delivery. This
`method alloWs for doWnstream insertion of additional data.
`An integrated radio location and communication system
`for a mobile station is disclosed by MartineZ in US. Pat. No.
`4,651,156. Each mobile station carries a transceiver that
`issues radio signals that are received by tWo or more signal
`transceiver reference sites having ?xed, knoWn locations.
`The transceivers at the mobile station and the reference
`stations are continuously phase locked to the RF carrier
`signal from a nearby commercial radio station. The radio
`station and the mobile station each transmit a brief, distin
`guishable range tone at a knoWn sequence of times, and the
`range tone from each station is received by each reference
`station. From an analysis of the differences in arrival times
`of the range tones received from the radio station and from
`the mobile station, the reference stations determine the
`tWo-dimensional location of the mobile station. The mobile
`station uses the beat signal betWeen tWo RF subcarrier
`frequencies to generate its range tone signal and to distin
`guish that mobile station transmissions from the transmis
`sions of any other mobile station.
`Young et al, in US. Pat. No. 4,660,193, disclose use of
`tWo SCA FM subcarrier signals, the ?rst being amplitude
`modulated and the second being phase modulated, to pro
`vide a digital data transmission system. A subcarrier signal
`Within this system may also be modulated to carry audio
`signals.
`A multichannel FM subcarrier broadcast system that
`provides a sequence of relatively closely spaced channels,
`using independent sidebands of suppressed carriers, is dis
`closed by Karr et al in US. Pat. No. 4,782,531. The sideband
`signals are generated in pairs and are phase shifted before
`transmission. Upon receipt of the transmitted signals, the
`process is reversed. An earlier patent, US. Pat. No. 3,518,
`376, issued to Caymen and Walker, discloses a similar
`approach Without use of signal phase shifting of pairs of
`sideband signals.
`In US. Pat. No. 4,799,062, Sanderford et al disclose a
`radio location method that uses a central processing station,
`a plurality of signal repeater base stations With ?xed, knoWn
`locations, and a mobile station With a knoWn location at any
`time. The central station transmits a master grid synchroni
`Zation pulse, Which serves as a time reference, to the other
`stations at a selected sequence of times. A roving station
`With unknoWn location transmits a pulse that is received by
`three or more base stations and is retransmitted to the central
`station. The central station determines the location of the
`roving station using the differences in time of arrival at each
`base station of the pulse transmitted by the roving station.
`The mobile station (With knoWn location) also transmits a
`pulse from time to time, and its knoWn location is compared
`With its computed location by the central station to deter
`mine any multipath compensation required to reconcile the
`knoWn and computed locations of the mobile station. The
`multipath compensation for a mobile station adjacent to the
`roving station is applied to correct the computed location of
`the roving station.
`Ma, in US. Pat. No. 4,816,769, discloses receipt of SCA
`FM subcarrier signals for digital data paging at a radio
`receiver. The system measures signal-to-noise ratio of an
`output amplitude of a Costas loop, used to phase lock to the
`FM subcarrier frequency, to determine if the signal is
`suf?ciently strong to be processed.
`
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`A system for detection of radio Wave propagation time,
`disclosed by Ichiyoshi in US. Pat. No. 4,914,735, uses
`detection of phase differences for transmission of the signal
`over M (22) different knoWn signal paths to a target
`receiver. The transmitted signal includes a subcarrier signal,
`having a frequency that is higher than the transmitter clock
`frequency, modulated With a knoWn modulation signal. The
`receiver has M demodulators for the signals received by the
`M different paths and has a phase comparator to compare the
`computed phases for each of these received signals. The
`phase differences are proportional to the signal path length
`differences, if compensation for transmission line distortions
`is included.
`US. Pat. No. 5,023,934, issued to Wheeless, discloses a
`system for communication of graphic data using radio
`subcarrier frequencies. The data are broadcast on a subcar
`rier channel and received by a radio receiver that is con
`nected to a computer. The computer receives the subcarrier
`signals, displays the graphic data on a computer screen, and
`performs other functions, such as transmission error check
`ing and modi?cation of the displayed graphic data. The
`system is intended for Weather data communication and
`display.
`Westfall, in US. Pat. No. 5,073,784, discloses a system
`for location of a transmitter (“unknown”) at large distances,
`using a large netWork of pairs of spaced apart radio Wave
`receivers Whose locations are knoWn and Whose relative
`phases are synchroniZed. A signal, broadcast by the
`unknoWn transmitter at less than HF frequencies, is received
`at different time and space points by pairs of receivers.
`Simple geometrical computations alloW determination of the
`location of the unknoWn transmitter by comparing times of
`arrival of the transmitted signal.
`US. Pat. No. 5,170,487, issued to Peek, discloses use of
`FM sub-carrier signals for a pager system for mobile users.
`Aplurality of transmitters are used, each of Which transmits
`an FM subcarrier signal or a carrier signal modulated With
`a chosen message signal, slightly offset in time. Each
`page-receiving unit is assigned a time slot, during Which the
`receiving unit dials through the set of frequencies corre
`sponding to the FM subcarrier and modulated-carrier signals
`to determine if a page message has been sent for that mobile
`user.
`A system that alloWs determination of an absolute loca
`tion of a vehicle is disclosed by Kelley et al in US. Pat. No.
`5,173,710. FM subcarrier signals are received from three
`radio stations With knoWn locations but unknoWn relative
`phases by signal processors at the vehicle and at a ?xed
`station With knoWn location relative to the three radio
`stations. The ?xed station processor determines the relative
`phases of the three radio stations FM subcarrier signals and
`broadcasts this relative phase information to the vehicle. The
`vehicle processor receives this relative phase data and
`determines its absolute location, using the phases of the FM
`55
`signals it senses at its oWn location.
`Chon, in US. Pat. No. 5,193,213, discloses an FM
`broadcast band system for receipt of relatively high fre
`quency FM subcarrier signals. A tunable high pass receiver
`?rst circuit receives the carrier and a tunable loW pass
`second circuit receives the subcarrier signal. Each signal can
`then be separately processed.
`A navigation and tracking system using differential
`LORAN-C or differential Decca signalling is disclosed by
`Duffett-Smith in Us. Pat. No. 5,045,861. Areference station
`transmits a reference signal to a mobile station and to three
`or more local LORAN-C or Decca (?xed) stations having
`
`35
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`40
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`45
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`60
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`65
`
`5,936,572
`
`10
`
`15
`
`20
`
`4
`knoWn locations relative to the reference station. The ?xed
`stations retransmit the reference signal to the mobile station,
`Where the phase received signal differences are compared to
`determine the location of the mobile station.
`Most of these systems use a single communication
`system, rather than integrating tWo or more communication
`systems to provide location or navigation information for a
`mobile user.The systems that use FM signals are limited to
`a region With a diameter of about 50 km or less. Any LD
`system that uses a plurality of radio carrier or subcarrier
`signals to determine location of a user must, at some point,
`determine the relative phases of these signals in order to
`estimate, by triangulation or related techniques, the user
`location. If the apparatus that determines these relative
`phases is ?xed in location, this limits the ?exibility and the.
`siZe of the region over Which the LD system can be
`deployed. What is needed is apparatus: (1) that permits
`accurate estimation of the location of an object Wherever the
`object is located on or near the Earth’s surface and over
`regions of diameter hundreds or even thousands of km in
`diameter; (2) that is mobile or portable; (3) that can Work
`indoors or outdoors; (4) that can provide estimates of
`location With inaccuracies no greater than ten meters, and
`more preferably no greater than one meter; and (5) that can
`determine the relative phases of radioWave carrier or sub
`carrier signals used as part of a hybrid LD system to
`determine the location of a mobile user. Preferably, the
`system should alloW a choice betWeen location information
`provided by tWo or more location determination systems,
`based on a comparison of one or more parameters that
`measure signal robustness and/or signal quality and/or sys
`tem location for the signals received and analyZed by each
`communication system. Preferably, in one mode of opera
`tion the system should alloW determination of location using
`three ?xed signal sources and a mobile phase detection
`source.
`
`SUMMARY OF THE INVENTION
`These needs are met by the invention, Which provides an
`integrated, mobile or portable system for location determi
`nation that combines bene?cial features of tWo or more LD
`systems. The invention is method and apparatus for deter
`mining the location of an object or user, or of a signal
`antenna or receiver carried or transported by the user. The
`system includes three or more spaced apart transmitters of
`radioWaves (e.g., FM carrier or subcarrier), operating With
`different radio carrier frequencies or With subcarrier fre
`quency displaced from the carrier frequency fC by a selected
`amount or a multiple thereof, With each radio transmitter
`being positioned at ?xed, knoWn locations, such as nearby
`radio stations. The system also includes a portable radio
`carrier or subcarrier signal antenna and receiver/processor,
`located at the user Whose location is to be determined, that
`receives and analyZes the radio carrier or subcarrier signals
`and determines the location of the FM antenna at selected
`times. FM subcarrier signals can be received at substantially
`all locations outside or inside a building or structure, if the
`FM subcarrier signal transmitter is Within a selected distance
`of no more than about 50 km from the FM antenna and
`receiver. Each of the transmitted radio LD signals has an
`associated phase that may be knoWn initially but that may
`change from time to time. This radio LD system may operate
`in a manner parallel to, but different from, the FM subcarrier
`signal system disclosed by Kelley et al in US. Pat. No.
`5,173,710, discussed above.
`The system also includes a second mobile or portable LD
`system, referred to here as an “outdoor LD system” and
`
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`integrated With the radio LD system, that may be a GPS,
`GLONASS or other satellite-based positioning system
`(SATPS) or a ground-based system such as Loran, Omega,
`Tacan, Decca, JTIDS Relnav or PLRS. The outdoor LD
`system has an LD signal antenna and receiver/processor that
`receives LD signals and is positioned at the location of the
`user. The outdoor LD system operates independently of the
`radio LD signal system, and each of these systems can
`determine the present location of the user at selected times.
`The outdoor LD system includes a mobile radio signal
`monitor that receives the radio LD signals and determines
`the relative phases of these radio LD signals from time to
`time as part of the LD process.
`The radio LD system and the outdoor LD system are
`electrically connected by an LD controller that (1A) deter
`mines a signal quality parameter (e.g., signal strengths or
`signal-to-noise ratios) of the LD signals used With each LD
`system or (1B) estimates the user location, using at least one
`of the LD systems, and (2) selects the more appropriate LD
`system, based upon relative signal quality or estimated user
`location, to provide the user location and displays visual or
`audible indicia of this user location.
`Determination of the location of a mobile user by employ
`ing signals from tWo or more LD systems offers the advan
`tage that each of these LD systems can be utiliZed in
`situations Where that system is most likely to provide an
`accurate estimate of the location. The invention uses a
`combination of radiofrequency carrier or subcarrier Waves
`and another source of electromagnetic (em) Waves to alloW
`location determination for a mobile user inside a building or
`other structure as Well as outside such structures. Where
`radiofrequency carrier or subcarrier Waves are used for
`location determination of the user(e.g., inside a building or
`other structure), the LD signals are received from three or
`35
`more radio signal sources With ?xed, knoWn locations. A
`mobile radio LD signal monitor, part of the outdoor LD
`system, determines the relative phases of the radio signals
`from time to time as part of the LD process here.
`In one mode of operation, the radio LD system and the
`outdoor LD system are positioned adjacent to each other and
`form a single, integrated, hybrid LD package or system that
`can be moved around With the user. The outdoor LD system
`includes a radio LD signal monitor that receives the radio
`LD signals, determines the relative phases of these radio LD
`signals, and provides this relative phase information for use
`by the radio LD system.
`In another mode of operation, the radio LD system is
`portable, moves With the user, and is not physically attached
`to the mobile outdoor LD system, Which may also be
`portable or mobile. The outdoor LD system again includes
`a radio LD signal monitor that receives the radio LD signals,
`determines the relative phases of these radio LD signals, and
`provides this relative phase information for use by the radio
`LD system, using a cable or Wireless link betWeen the
`outdoor LD system and the radio LD system. Here, the radio
`LD system and the outdoor LD system are physically
`separated and can move independently of each other, but
`these tWo systems form an integrated, hybrid LD system.
`The outdoor LD unit can serve solely as a radio LD signal
`monitor that determines its oWn location and provides radio
`LD signal relative phase information for the radio LD unit.
`Alternatively, the outdoor LD unit can provide a separate
`determination of user location and complement the radio LD
`unit’s LD process. In this latter approach, the integrated
`system compares a signal robustness parameter, such as
`received signal strength, or a signal quality parameter, such
`
`45
`
`55
`
`65
`
`5,936,572
`
`6
`as signal-to-noise ratio, or estimates location to determine
`Whether the radio LD signals or the outdoor LD signals Will
`be used to determine the present location of the object or
`user that carries the apparatus.
`
`BRIEF DESCRIPTIONS OF THE DRAWINGS
`
`FIGS. 1, 3, 4 and 5 schematically illustrate use of the
`invention in three embodiments.
`FIG. 2 is a graphical vieW of a representative FM sub
`carrier signal spectrum used in the invention.
`FIGS. 6 and 7 are schematic vieWs of an LD unit
`according to tWo embodiments.
`FIGS. 8 and 9 are How charts of suitable procedures for
`location determination using only radio LD signals, and
`using radio LD signals and outdoor LD signals, respectively.
`
`DESCRIPTION OF BEST MODES OF THE
`INVENTION
`
`In FIG. 1, a hybrid LD system 11 is carried or transported
`by or attached to a user 12 and includes a radio LD unit 13.
`The radio LD unit 13 preferably includes an FM carrier or
`subcarrier signal antenna 15 and FM subcarrier signal
`receiver/processor 17. The radio LD unit 13 receives radio
`LD signals from three or more radio LD signal sources 21,
`23 and 25 that have ?xed locations With.knoWn location
`coordinates (Xm, ym, Zm) for radio LD signal source no.m
`(m=21,23,25).
`An FM subcarrier signal may have an associated fre
`quency of about fC:19 kHZ, Where fC is the FM carrier
`frequency that lies in the range 88—108 MHZ. Alternatively,
`a higher order displacement from the carrier frequency (e. g.,
`fcz38 kHZ or fcz57 kHZ) may be used, as permitted by
`F.C.C. regulations. The sources of these FM subcarrier
`signals may be a plurality of FM broadcasting stations
`located in or near the user 12. In this event, the subcarrier
`signals are obtained by ?ltering and sequentially demodu
`lating the total FM signals (carrier signal plus message
`signal plus subcarrier signal) to remove all but a subcarrier
`signal of a chosen frequency. The FM subcarrier signal
`antenna 15 receives the FM subcarrier signals and passes
`these signals to the associated receiver/processor 17 for
`determination of the estimated present location of the FM
`antenna 15.
`The relative phases of the radio signals transmitted by the
`sources 21, 23 and 25 may change from time to time. When
`the radio LD unit 13 is provided With a recent measurement
`of these relative phases, the radio LD unit can determine the
`location of its antenna 15, using intersections of three or
`more hyperboloids that are de?ned by the relative times of
`arrival of the three radio LD signals at the antenna. The
`receiver/processor 17 also receives radio LD signal phase
`information that is used in determination of the estimated
`present location of the radio LD antenna 15. The embodi
`ment shoWn in FIG. 1 also includes a second (outdoor) LD
`system 31 that is a satellite-based positioning system
`(SATPS), such as GPS, GLONASS or a similar system.
`FIG. 2 illustrates the full FM signal spectrum and the
`useful portion of the signal that remains (fC:19 kHZ) after
`frequency ?ltering. FM subcarrier signals can be used for all
`monitoring of the present location of a user 12, Which may
`be a person or an inanimate object such as a controllable
`ambulatory machine or robot, inside and outside buildings
`and other structures. This approach has the advantage of
`simplicity: only one set of radioWaves is used for location
`determination. FM signals are less subject to noise and other
`
`T-Mobile / TCS / Ericsson EXHIBIT 1008
`T-Mobile / TCS / Ericsson v. TracBeam
`Page 12
`
`

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`15
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`25
`
`35
`
`7
`interference than are other signals, such as AM signals.
`Alternatively, an FM carrier or subcarrier signal can be
`replaced by an AM carrier or subcarrier signal, obtained by
`?ltering an AM signal at a frequency referenced to the AM
`carrier frequency. Alternatively, determination of the present
`location of the user 12 can be made using a radio LD unit
`that receives and analyZes radio LD signals transmitted from
`tWo or more radio LD signal sources.
`The hybrid LD system 11 shoWn in FIG. 1 includes a
`satellite-based outdoor LD unit 31, also carried or trans
`ported by or attached to the user 12. This outdoor LD unit
`31includes an outdoor LD signal antenna 33 and associated
`outdoor LD signal receiver/processor 35 that receive out
`door LD signals from three or more satellites 41, 43, 45
`Whose locations at any time are knoWn With acceptable
`accuracy. The antenna 33 receives the outdoor LD signals
`and the receiver/processor 35 determines the present loca
`tion of this antenna, using Well knoWn techniques. The
`Global Positioning System (GPS) and the Global Orbiting
`Navigation Satellite System (GLONASS)are tWo suitable
`eXamples of satellite-based outdoor LD systems and are
`discussed in detail beloW.
`The outdoor LD unit 31 in FIG. 1 includes a radio LD
`signal antenna and receiver/processor 37 and controller/
`interface 39 that also receives radio LD signals from the
`radio LD sources 21, 23 and 25, determines the relative
`phases of these radio LD signals, and provides this relative
`phase information With little or no time delay for use by the
`radio LD unit 13. In FIG. 1, the radio LD unit 13 and the
`outdoor LD unit 31 are adjacent to each other and are both
`carried by, transported by, or attached to the user 12. The
`outdoor LD unit 31 determines the (approximate) location of
`itself and of the adjacent radio LD unit 13 and uses this
`information in determining the relative phases of the radio
`LD signals transmitted by the sources 21, 23 and 25. Use of
`a mobile outdoor LD unit 31 to receive radio LD signals and
`to determine the relative phases of such signals is an
`important feature of the invention.
`In one mode of operation in FIG. 1, the outdoor LD unit
`31 serves only as a mobile radio LD signal monitor 37, for
`Which present location can be approximately determined. In
`another mode of operation, the outdoor LD unit 31 also
`complements the radio LD unit 13 by providing an inde
`pendent determination of location of the hybrid LD unit 11.
`FIG. 3 schematically illustrates a second mode of opera
`tion of the invention, in Which the radio LD unit 13 is made
`portable and moves With the user 12, independently of
`movement of, and spaced apart from, the outdoor LD unit
`31. The radio LD unit 13 and the outdoor LD unit 31 are
`parts of an integrated hybrid LD system, as before, but