Ulllted States Patent [19]
`Dussell et al.
`
`US005938721A
`[11] Patent Number:
`[45] Date of Patent:
`
`5,938,721
`Aug. 17, 1999
`
`[54] POSITION BASED PERSONAL DIGITAL
`ASSISTANT
`
`[75] Inventors: William O. Dussell, Pescardero; James
`M- Janky, LOS Altos; John R
`Schipper, Palo Alto; David J. COW],
`Sunnyvale, all of Calif.
`
`[73] Assignee: Trimble Navigation Limited,
`Sunnyvale, Calif.
`
`[21] Appl. No.: 08/738,983
`.
`_
`Oct‘ 24’ 1996
`Flled'
`t22]
`[51] Int. 01.6 ........................ .. G01C 21/00; G06F 165/00
`[52] US. Cl. ........................................... .. 701/211; 701/213
`[58] Field of Search .............................. .. 701/1 211 213
`701/300. 342/357 457. 340/995 996. 3’64/765 05’
`’
`’
`’
`’
`765 07 705' 08’
`'
`’
`'
`
`[56]
`
`References Cited
`
`U-S- PATENT DOCUMENTS
`434/112
`7/1991 Friedman
`5 032 083
`342/357
`"""""""""""""
`5/1994 Brown
`573117194
`340/994
`8/1995 ROSS _______ __
`5:444:444
`. . . . . .. 701/1
`5,457,629 10/1995 Miller et a1. . . . . . . . . . . . . .
`434/112
`5,470,233 11/1995 Fruchterman et a1. ..
`364/443
`5,559,707
`9/1996 Delorme et al. ....... ..
`5,576,687 11/1996 Blank et a1. .......................... .. 340/438
`
`7/1997 Loomis et a1. ........................ .. 342/357
`5,646,629
`5,682,525 10/1997 Bouve et al.
`395/615
`5,699,244 12/1997 Clark, Jr. et al.
`364/420
`370/313
`577327074
`3/1998 Spam etat
`5,790,974
`8/1998 TognaZZmi ............................ .. 701/204
`Primary Examiner—Michael J. Zanelli
`Attorney, Agent, or Firm—Blakely, Sokoloff, Taylor &
`Zafman LLP
`
`ABSTRACT
`[57]
`A task description is stored in a database accessible by a
`mobile computer system. The mobile computer system
`receives positioning information corresponding to its geo
`graphic location and indexes the database based on the
`positioning information When the information indicates that
`the mobile Computer System is in a geographic location that
`facilitates Completion of a task associated With the task
`description. The database may be resident in the mobile
`computer system or accessible in other Ways, for example,
`via the Internet. The task description preferably includes a
`geocode Which corresponds to the geographic location at
`Which completion of the task may be facilitated. The task
`description may also include textual, voice or other message
`Which can be displayed and/or played back to a user. The
`positioning information may be obtained from a GPS
`satellite, a GLONASS satellite or a pseudolite. The mobile
`computer system may be a portable unit, such as a PDA, or
`integrated Within a vehicle.
`
`35 Claims, 2 Drawing Sheets
`
`7/52
`
`5
`
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`
`Petitioner Apple Inc. - Exhibit 1006, p. 1
`
`

`

`U.S. Patent
`
`Aug. 17,1999
`
`Sheet 1 012
`
`5,938,721
`
`Ig.
`
` Frontend
`
`Procese-or 56
`
`5
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`
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`LocationDeterminationUnit
`
` 0
`
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`
`Petitioner Apple Inc. - Exhibit 1006, p. 2
`
`330]N?‘
`
`% ‘
`
`SD
`
`Petitioner Apple Inc. - Exhibit 1006, p. 2
`
`

`

`U.S. Patent
`
`Aug. 17,1999
`
`Sheet 2 of2
`
`5,938,721
`
`Fig. 2
`
`Petitioner Apple Inc. - Exhibit 1006, p. 3
`
`

`

`1
`POSITION BASED PERSONAL DIGITAL
`ASSISTANT
`
`FIELD OF THE INVENTION
`
`The present invention relates generally to real time posi
`tioning systems and, more particularly, to the use of such
`systems to control access to computer databases to assist in
`task scheduling.
`
`BACKGROUND
`
`Personal Digital Assistants (PDAs) have become more
`and more common in today’s society. The term PDA refers
`generally to mobile computer systems, typically handheld,
`Which users employ for a variety of tasks such as storing
`telephone and address lists (databases), calendaring
`information, task (i.e., to-do) lists, etc. Some PDAs also
`incorporate a Wireless communication link, alloWing the unit
`to operate as a portable facsimile device, Internet access
`device and/or pager. Further, PDAs can be con?gured to
`operate With Global Positioning System (GPS) receivers as
`described in US. Pat. No. 5,528,248 to Steiner et al., entitled
`“Personal Digital Location Assistant Including a Memory
`Cartridge, A GPS Smart Antenna and a Personal Computing
`Device” assigned to the assignee of the present invention
`and incorporated by reference herein.
`The GPS utiliZes signals transmitted by a number of
`in-vieW satellites to determine the location of a GPS antenna
`Which is connected to a receiver. Each GPS satellite trans
`mits tWo coded L-band carrier signals Which enable some
`compensation for propagation delays through the iono
`sphere. Each GPS receiver contains an almanac of data
`describing the satellite orbits and uses ephemeris corrections
`transmitted by the satellites themselves. Satellite to antenna
`distances may be deduced from time code or carrier phase
`differences determined by comparing the received signals
`With locally generated receiver signals. These distances are
`then used to determine antenna position. Only those satel
`lites Which are suf?ciently above the horiZon can contribute
`to a position measurement, the accuracy of Which depends
`on various factors including the geometrical arrangement of
`the satellites at the time When the distances are determined.
`Distances measured from an antenna to four or more
`satellites enable the antenna position to be calculated With
`reference to the global ellipsoid WGS-84. Local northing,
`easting and elevation coordinates can then be determined by
`applying appropriate datum transformation and map projec
`tion. By using carrier phase differences in any one of several
`knoWn techniques, the antenna coordinates can be deter
`mined to an accuracy on the order of :1 cm.
`Although US. Pat. No. 5,528,248 describes hoW a GPS
`receiver can be integrated With a PDA to display navigation
`information for a user, it does not describe hoW positioning
`information provided to the PDA can be used in other Ways.
`
`SUMMARY OF THE INVENTION
`
`According to one embodiment, a computer assisted
`method of scheduling tasks is provided. The method alloWs
`a task description to be stored in a database accessible by a
`mobile computer system. The mobile computer system
`receives positioning information corresponding to its geo
`graphic location and indexes the database based on the
`positioning information When the information indicates that
`the mobile computer system is in a geographic location that
`facilitates completion of a task associated With the task
`description.
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`The database may be resident in the mobile computer
`system or accessible in other Ways, for eXample, via the
`Internet. The task description preferably includes a geocode
`Which corresponds to the geographic location at Which
`completion of the task may be facilitated. The task descrip
`tion may also include textual, voice or other messages Which
`can be displayed and/or played back to a user. The posi
`tioning information may be obtained from a GPS satellite, a
`GLONASS satellite or a pseudolite. The mobile computer
`system may be a portable unit, such as a PDA, or integrated
`Within a vehicle.
`A second embodiment provides a computer assisted
`method of using a geocoded database. In this embodiment,
`a mobile computer system is transported to a ?rst location
`having ?rst geographic coordinates at a ?rst time. At the ?rst
`location, RF signals Which contain information indicative of
`the location of a source of their transmission are received
`and processed to derive the geographic coordinates of the
`?rst location. The geographic coordinates of the ?rst loca
`tion are associated With a descriptor indicative of the ?rst
`location in a database associated With the mobile computer
`system so as to form a geocoded entry in the database and
`a task to be accomplished at the ?rst location is similarly
`associated With the geocoded entry in the database.
`The mobile computer system is transported to a second
`location at a second time and RF signals containing infor
`mation indicative of the source of the signals are received
`and processed to determine the geographic coordinates of
`the second location. The geographic coordinates of the
`second location are analyZed to determine Whether the
`second location is Within a predetermined range of the ?rst
`location and, if so, a user is alerted. The user may be alerted
`by displaying an alert message, such as a task description
`corresponding to the task to be accomplished at the ?rst
`location, on a display associated With the mobile computer
`system.
`Afurther embodiment provides a mobile computer system
`having a location determination unit con?gured to receive
`and process RF signals containing information indicative of
`the location of a source of the signals, a database coupled to
`the location determination unit and including location coor
`dinates indicative of a location of interest and a database
`interface unit con?gured to access the database according to
`the location of the mobile computer system.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`The present invention is illustrated by Way of eXample
`and not limitation in the ?gures of the accompanying
`draWings in Which:
`FIG. 1 illustrates a digital system con?gured With a
`mobile computer system, a location determination unit and
`a database according to one embodiment; and
`FIG. 2 illustrates a vehicle con?gured in accordance With
`the present invention located near a pick-up location.
`
`DETAILED DESCRIPTION
`The folloWing description of a position based personal
`digital assistant sets forth numerous speci?c details in order
`to provide a thorough understanding of the present inven
`tion. HoWever, after revieWing this speci?cation, it Will be
`apparent to those skilled in the art that the present invention
`may be practiced Without some or all of these speci?c
`details. In other instances, Well knoWn structures, program
`ming techniques and devices have not been described in
`detail in order not to unnecessarily obscure the present
`invention.
`
`Petitioner Apple Inc. - Exhibit 1006, p. 4
`
`

`

`3
`Some portions of the detailed description Which follows
`are presented in terms of operations on data Within a
`computer memory. These descriptions are the means used by
`those skilled in the relevant arts to most effectively convey
`the substance of their Work to others skilled in the art. The
`steps are those requiring physical manipulations of physical
`quantities. Usually, though not necessarily, these quantities
`take the form of electrical or magnetic signals capable of
`being stored, transferred, combined, compared and other
`Wise manipulated. It has proven convenient at times, prin
`cipally for reasons of common usage, to refer to these
`signals as bits, values, elements, symbols, characters, terms,
`numbers or the like. It should be borne in mind, hoWever,
`that all of these and similar terms are to be associated With
`the appropriate physical quantities and are merely conve
`nient labels applied to these quantities. Unless speci?cally
`stated otherWise, it Will be appreciated that throughout the
`description of the present invention, use of terms such as
`“processing”, “computing”, “calculating”, “determining”,
`“displaying” or the like, refer to the action and processes of
`a computer system, or similar electronic computing device,
`that manipulates and transforms data represented as physical
`(electronic) quantities Within the computer system’s regis
`ters and memories into other data similarly represented as
`physical quantities Within the computer system memories or
`registers or other such information storage, transmission or
`display devices.
`Referring to the accompanying FIG. 1, a digital system 5
`having a database 10, a mobile computer system 20 and a
`location determination unit 30 is shoWn. Database 10 may be
`a separate database maintained at some location remote from
`mobile computer system 20 or it may be a local database
`maintained Within mobile computer system 20. Mobile
`computer system 20 may be a personal digital assistant or
`other mobile computer system (e.g., a notebook or other
`personal computer) or it may be an integrated computer
`system Within a vehicle. Location determination unit 30 may
`be a Global Positioning System (GPS) receiver of other unit
`capable of determining a geographic location of an accom
`panying antenna 32.
`It should be appreciated that although database 10, mobile
`computer system 20 and location determination unit 30 are
`illustrated as distinct units, in some embodiments these
`items may comprise a single unit, such as a personal digital
`assistant or notebook computer. In such embodiments, loca
`tion determination unit 30 may be housed Within a card (PC
`Card) compatible With the Personal Computer Memory Card
`International Association PC Card Standard, release 2.0,
`published by the Personal Computer Memory Card Interface
`Association (PCMCIA), September 1991. In other
`embodiments, location determination unit 30 may comprise
`a GPS Smart Antenna or other GPS receiver.
`In yet other embodiments, elements of digital system 5
`may form an integrated system Within a vehicle, aircraft,
`boat or other mobile unit and database 10 may be stored
`Within a memory device housed in a PC Card or on another
`transportable computer readable media such as a disk or CD
`ROM. Database 10 is preferably a geocoded database and
`Will be described in further detail beloW. In some cases,
`mobile computer system 20 may share some circuitry With
`location determination unit 30. For eXample, the tWo units
`may share a digital signal processor or other microprocessor
`Which performs the computations required to derive the
`geographic location of the digital system 5 (i.e., antenna 32)
`using signals transmitted by GPS satellites or other sources
`(e.g., GLONASS satellites and/or pseudolites).
`Mobile computer system 20 typically includes a micro
`processor 21 and a system bus 22. Microprocessor 21 is
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`coupled to system bus 22, alloWing microprocessor 21 to
`communicate With the other elements Which make up mobile
`computer system 20, location determination unit 30 and
`database 10. Mobile computer system 20 may also include
`a ROM 23 Which typically stores computer readable instruc
`tions to be executed by microprocessor 21 upon poWer up.
`Such instructions may further include an operating system
`for mobile computer system 20 Where such an operating
`system is not stored Within another nonvolatile memory.
`Mobile computer system 20 may further include a memory
`(Mem) 24 Which may be a volatile memory (i.e., a random
`access memory or RAM) for use during periods When
`mobile computer system 20 is poWered up. The Mem 24
`may also include a hard disk or other long term, nonvolatile
`memory for storage of application programs and/or data
`When mobile computer system 20 is not poWered up. In
`other cases, these application programs may be stored in
`ROM 23. ROM 23 and Mem 24 are typically coupled to
`system bus 22 to alloW access by microprocessor 21. In
`some embodiments, ROM 23 and Mem 24 may be coupled
`to microprocessor 21 over a separate memory bus (not
`shoWn).
`To facilitate use of mobile computer system 20 by an
`operator, user interface 25 and display 26 are provided and
`each are coupled to system bus 22. User interface 25 may
`include a familiar keyboard and mouse (or other pointing
`device such as a pen). In addition, some mobile computer
`systems 20 may have a voice synthesiZer included as part of
`user interface 25 to alloW activation of various functions by
`voice command. In other embodiments, the user interface 25
`may be a touch sensitive screen Which also forms part of a
`visual display 26. Other user interfaces may also be used.
`Display 26 may be a visual display such as a liquid crystal
`display screen, or other screen. In other embodiments,
`display 26 Will include alert lights, such as those commonly
`found on automobile dashboards. Where mobile computer
`system 20 is integrated Within a vehicle, display 26 may
`form part of a heads up display or dashboard display Within
`the vehicle. When display 26 forms part of a heads up
`display, the heads up display may provide information such
`as the vehicle’s current speed and location (e.g., latitude and
`longitude). The heads up display may further include an area
`for displaying teXt messages, such as the task description
`stored in database 10. Alternatively, the heads up display
`may only provide an alert indication (such as an icon or an
`alert symbol, etc.). Such a heads up display may be dis
`played on an appropriate section of the vehicle’s Windshield,
`such as a corner of the Windshield near the driver’s position
`or directly above the steering Wheel, so as to alloW for easy
`use by the driver Without obstructing the driver’s vieW of the
`road. Display 26 may also include a voice synthesiZer
`(optionally shared With user interface 25) and speaker sys
`tem to alloW for playback of voice messages. This arrange
`ment may alloW for voice messages to be played back
`through the vehicle’s existing sound system (e.g., an
`AM/FM stereo system). Other displays may also be used.
`Mobile computer system 20 also includes interface 27
`Which alloWs mobile computer system 20 to communicate
`With location determination unit 30. Interface 27 provides an
`electrical connection betWeen mobile computer system 20
`and location determination unit 30 and may correspond to an
`RS-232 or RS-422 interface. In some embodiments, Where
`location determination unit 30 comprises a GPS server
`located as a unit on a vehicle bus system, interface 27 alloWs
`for proper electrical coupling betWeen mobile computer
`system 20 and a vehicle communication bus. As such,
`interface 27 Will be con?gured according to the protocol for
`message eXchange across the bus.
`
`Petitioner Apple Inc. - Exhibit 1006, p. 5
`
`

`

`5,938,721
`
`5
`A communications bus is useful for delivering data and
`other electronic signals from one device to another in a
`vehicle. Without use of such a bus, as the number of vehicle
`devices increases, duplication of vehicle sensors and
`increasing use of point-to-point Wiring betWeen devices is
`required, Which can result in large and needlessly complex
`Wiring looms. Use of such a bus alloWs use of unduplicated
`vehicle sensors and minimizes use of point-to-point Wiring,
`by making all measurements and signals available simulta
`neously to all devices that are connected by the bus. Several
`standards for such vehicle bus systems exist, for example,
`the 11587 and 11708 speci?cations for bus systems pub
`lished by the Society of Automotive Engineers and the
`standards for communication buses as set forth by the
`Society of Automotive Engineers and Controller Area Net
`Work (CAN) as documented in ISO 11893:1993, for high
`speed applications, and in ISO 11519.1:1994—ISO
`11519.4:1994, for loW speed applications, all of Which are
`incorporated herein by reference.
`The 11587 (issued as 1988 January and in revised form as
`1994 1 an. 10 and later revisions) and 11708 (issued as 1986
`January and in revised form as 1990 Oct. 5 and later
`revisions) speci?cations recite standards and de?ne signal
`formats for use of microcomputer systems in heavy duty
`vehicle applications, such as provision of electronic data on
`vehicle and component performance, vehicle routing and
`scheduling, vehicle driver information and vehicle cargo
`reformation. Each signal that is transmitted using a signal
`bus complying With these standards includes: (1) a message
`identi?cation (MID) number (three digits from 0—255, With
`MIDs 0—127 being de?ned in 11708 and MIDs 128—255
`de?ned in 11587); (2) one or more measured parameter
`values associated With and identi?ed by the MID; and (3) a
`check sum. Parameter update time intervals and priorities for
`transaction of different groups of MIDs are currently being
`developed.
`The user segment components of a GPS system carried on
`a vehicle are connected using a communications bus in the
`same manner as are other devices on the bus. An electrical
`connection betWeen the server and the bus is made using
`interface circuitry that complies With applicable standards.
`Inexpensive interface ICs are readily available for buses that
`conform to the CAN standards.
`Typically, each device that is part of a GPS user segment
`on a vehicle Will have a unique bus address. GPS data can
`be provided or delivered in tWo Ways. First, a GPS user
`segment device (such as location determination unit 30) can
`provide vehicle location, vehicle velocity and/or absolute or
`local time information for use on the vehicle, using packets
`that identify the source and destination(s) addresses of such
`data on the bus and that identify the type of data (location,
`velocity, time, etc.) contained in the packet.
`Second, the GPS data can be provided at a central server,
`and any device (such as mobile computer system 20) requir
`ing such data can address a data request to the GPS server.
`The server then packages the requested data in a packet,
`frame or other suitable format and sends the packaged data
`directly to the requesting device, using the bus. This
`approach may be more ?exible in that it (1) alloWs a client
`to request and promptly receive GPS data and non-GPS data,
`(2) alloWs data to be requested and received only When such
`data is needed, rather than transporting all data on the bus as
`soon as such data is available, regardless of need, and (3)
`provides such data in more convenient formats for indi
`vidual client use. Related GPS data may include GPS
`receiver health, GPS receiver correction status, vehicle
`tracking status and other similar information. Information
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`can also be provided to, and stored on, the server to improve
`or correct the GPS receiver performance. Such information
`may include real time clock information, to reduce the time
`required for initial acquisition or reacquisition of GPS
`satellite signals, and may include DGPS correction data to
`improve the accuracy of real time determination of vehicle
`present location. Such DGPS correction data may be
`obtained from a variety of commercial or other sources
`using Well-knoWn radio-based communications links such
`as FM subcarriers, private or packet radio links to private
`servers or servers accessed through the Internet or other
`cellular phone links.
`Location determination unit 30 has an associated antenna
`32 for receiving signals from GPS satellites and/or other
`sources of GPS signals (e.g., pseudolites, FM subcarriers,
`etc.) Antenna 32 provides the received signals to Receiver
`(Rx) Front-end 34 Where the signals are doWnconverted and
`often digitiZed for further processing by GPS Processor 36.
`The manner in Which GPS processing is accomplished is
`Well knoWn in the art. Brie?y, GPS receivers normally
`determine their position by computing relative times of
`arrival of signals transmitted simultaneously from a multi
`plicity of GPS satellites. These satellites transmit, as part of
`their message, both satellite positioning data as Well as data
`on satellite clock timing and “ephemeris” data for each
`satellite. Using this data, the GPS receiver computes pseu
`doranges Which are simply the time delays measured
`betWeen the received signal from each satellite and a local
`clock.
`Many GPS receivers utiliZe correlation methods to com
`pute pseudoranges. GPS signals contain high rate repetitive
`signals called pseudorandom (PN) sequences. The codes
`available for civilian applications are called C/A codes, and
`have a binary phase-reversal rate, or “chipping” rate, of
`1.023 MHZ and a repetition period of 1023 chips for a code
`period of 1 msec. The code sequences belong to a family
`knoWn as Gold codes. Each GPS satellite broadcasts a signal
`With a unique Gold code. For a signal received from a given
`GPS satellite, folloWing the doWnconversion process to
`baseband, a correlation receiver multiplies the received
`signal by a stored replica of the appropriate Gold code
`contained Within its local memory, and then integrates, or
`loWpass ?lters, the product in order to obtain an indication
`of the presence of the signal. This process is termed a
`“correlation” operation. By sequentially adjusting the rela
`tive timing of this stored replica relative to the received
`signal, and observing the correlation output, the receiver can
`determine the time delay betWeen the received signal and a
`local clock. The initial determination of the presence of such
`an output is termed “acquisition.” Once acquisition occurs,
`the process enters the “tracking” phase in Which the timing
`of the local reference is adjusted in small amounts in order
`to maintain a high correlation output. The correlation output
`during the tracking phase may be vieWed as the GPS signal
`With the pseudorandom code removed, or, in common
`terminology, “despread.” This signal is narroW band, With
`bandWidth commensurate With a 50 bit per second binary
`phase shift keyed data signal Which is superimposed on the
`GPS Waveform.
`The above operations are performed by GPS processor 36
`(or by a common processor such as microprocessor 21
`Where location determination unit 30 and mobile computer
`system 20 share such circuitry) and may be achieved in
`dedicated hardWare or softWare. The output Will be the
`geographic coordinates (e.g., latitude, longitude and
`altitude) of the antenna 32. It is assumed here that antenna
`32 is positioned such that there is no appreciable difference
`
`Petitioner Apple Inc. - Exhibit 1006, p. 6
`
`

`

`5,938,721
`
`7
`between its geographic coordinates and those of mobile
`computer system 20. Also, the positioning information pro
`vided by location determination unit 30 may be enhanced
`through the use of DGPS techniques as is common in the art.
`The output of GPS processor 36 is communicated to
`mobile computer system 20 via interface 38. Interface 38
`may be an RS-232 or RS-422 interface. Alternatively, Where
`location determination unit 30 operates as a GPS server,
`providing location information to a variety of systems Within
`a vehicle, interface 38 Will be con?gured to provide appro
`priate electrical coupling to a bus interconnecting the vari
`ous vehicle systems.
`As mentioned above, database 10 is preferably a geo
`coded database. This term is best understood With reference
`to the manner in Which digital system 5 is used by an
`operator. Typically, mobile computer system 20 Will store
`various application programs, including a scheduling pro
`gram Which alloWs an operator to store reminders in the
`form of “To-Do” lists or other forms. Such scheduling
`programs are common in the art and often alloW the user to
`prioritiZe tasks to be accomplished according to a variety of
`criteria, including due dates, etc. The present invention
`provides a means by Which tasks can be scheduled and/or
`prioritiZed based on location. Tasks are assigned using a task
`descriptor (e.g., a text and/or voice message describing the
`task) and stored in database 10. Typically, the task descriptor
`Will include a reference indicating a location at Which the
`task is to be accomplished. This may be a set of geographic
`coordinates or, more typically, a name of a business or other
`location. To illustrate, if the task descriptor is a text message
`such as “PICK UP MILK”, an appropriate reference might
`be “GROCERY STORE”.
`FIG. 2 illustrates an exemplary situation Where a vehicle
`100 includes a digital system 5. Vehicle 100 has reached a
`location 102 Which is located a distance “R” from a GRO
`CERY STORE 104. Assuming that a user has previously
`stored a “PICK UP MILK” task With a reference to the
`GROCERY STORE as described above, the user Will be
`alerted to “PICK UP MILK” in accordance With the present
`invention. The manner in Which this is accomplished is
`discussed further beloW.
`After entering the task description in the database, the
`user Will transport mobile computer system 20 such that it is
`able to access the database 10 (either because database 10 is
`contained Within mobile computer system 20, for example,
`Within Mem 24 or as a PC card or other computer readable
`storage medium, or because the units are linked via a
`Wireless communications link Which may be routed through
`a cellular telephone or modem system and/or the Internet)
`and is further able to receive position information from
`location determination unit 30. Often, mobile computer
`system 20 Will be a PDA and database 10 Will either be
`stored Within internal memory (e.g., Mem 24) or Within a
`memory unit on a PC Card or other device attached to the
`PDA. In such cases, the PDA may also include location
`determination unit 30. In other cases, the PDA may connect
`to a docking port or other coupling arrangement Within a
`vehicle. In these cases, location determination unit 30 may
`operate as a GPS server Within the vehicle as discussed
`above. Of course, mobile computer system 20 itself may be
`an integrated unit Within the vehicle, in Which case a
`memory component such as a PC Card or CD ROM on
`Which database 10 is stored may be the only unit transported
`by the user. The memory component Would be provided to
`an appropriate device (for example a PC Card port or CD
`ROM drive), thus making database 10 accessible by mobile
`computer system 20. Further, database 10 may be main
`
`15
`
`25
`
`35
`
`45
`
`55
`
`65
`
`8
`tained on the user’s home or business computer system and
`may be accessed by mobile computer system 20 via a
`Wireless communication link. In some cases, the communi
`cation link may be a cellular telephone link. Additionally, the
`communication link may route messages betWeen mobile
`computer system 20 and database 10 via the Internet using
`techniques Well knoWn in the art. Although such a link has
`not been shoWn in FIG. 1 in order not to obscure the
`draWing, it Will be appreciated that such a communication
`link Would alloW database 10 to be updated by more that one
`user at various times.
`At some point, location determination unit 30 Will receive
`and process GPS signals in the manner described above and
`Will provide geographic location coordinates to mobile
`computer system 20 via interface 38. These geographic
`location coordinates Will correspond to the geographic loca
`tion of antenna 32, hoWever, it is assumed that mobile
`computer system 20 is in close enough proximity to antenna
`32 such that the location of antenna 32 is substantially the
`same as the location of mobile computer system 20. This
`condition Will be satis?ed, for example, if mobile computer
`system 20 is transported Within the same vehicle as that on
`Which antenna 32 is located. Antenna 32 may be a patch
`antenna or other antenna suitable for mounting on a vehicle
`and capable of receiving GPS signals transmitted by GPS
`satellites or pseudolites.
`Once mobile computer system 20 has received the above
`mentioned geographic location coordinates (or other posi
`tioning information) provided by location determination unit
`30, microprocessor 21 Will use this information to index
`database 10. Recall that database 10 contains a task descrip
`tion With an associated location reference (e. g., “GROCERY
`STORE”). The location reference Will have an associated
`geocode, i.e., an associated set of geographic coordinates.
`This geocode is established at an earlier time, for example,
`by storing the location coordinates of the grocery store in the
`database 10 during an earlier trip to the store, and is
`associated With the location reference that goes With the task
`description. Thus, database 10 is a geocoded database that
`contains task descriptions With associated geocodes. Each
`time a task description is entered and associated With a
`location reference, a geocode (corresponding to the location
`reference) is automatically associated With the task descrip
`tion.
`NoW, microprocessor 21 uses current positioning infor
`mation provided by location determination unit 30 to index
`database 10 and retrieve task descriptions having associated
`geocodes Which are close in proximity (e.g., Within a city
`block radius) to the current geographic location of mobile
`computer 20. In this Way, a user can be alerted to a
`previously entered task based on the user’s current position.
`To continue the grocery store example, if mobile computer
`system 20