U.S. patent application number 09/846415 was filed with the patent office on 2001-08-30 for position based personal digital assistant.
Invention is credited to Cowl, David J., Dussell, William O., Janky, James M., Schipper, John F..
Application Number | 20010018663 09/846415 |
Document ID | / |
Family ID | 26989250 |
Filed Date | 2001-08-30 |
United States Patent
Application |
20010018663 |
Kind Code |
A1 |
Dussell, William O. ; et
al. |
August 30, 2001 |
Position based personal digital assistant
Abstract
A task description is stored in a database accessible by a
mobile computer system. The mobile computer system receives
positioning information corresponding to its geographic 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.
Inventors: |
Dussell, William O.;
(Pescardero, CA) ; Janky, James M.; (Los Altos,
CA) ; Schipper, John F.; (Palo Alto, CA) ;
Cowl, David J.; (Sunnyvale, CA) |
Correspondence
Address: |
BLAKELY SOKOLOFF TAYLOR & ZAFMAN
12400 WILSHIRE BOULEVARD, SEVENTH FLOOR
LOS ANGELES
CA
90025
US
|
Family ID: |
26989250 |
Appl. No.: |
09/846415 |
Filed: |
April 30, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09846415 |
Apr 30, 2001 |
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09334521 |
Jun 16, 1999 |
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09334521 |
Jun 16, 1999 |
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08738983 |
Oct 24, 1996 |
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5938721 |
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Current U.S.
Class: |
701/468 |
Current CPC
Class: |
G01C 21/26 20130101;
G08G 1/0962 20130101; G09B 29/106 20130101; G01S 19/11 20130101;
G01S 5/0009 20130101; G01S 19/41 20130101 |
Class at
Publication: |
705/9 |
International
Class: |
G06F 017/60 |
Claims
What is claimed is:
1. A computer assisted method of scheduling tasks, comprising the
steps of: storing a task description in a database, said database
being accessible by a mobile computer system; receiving at said
mobile computer system positioning information corresponding to the
geographic location of said mobile computer system; and indexing
said database based on said positioning information so as to
retrieve said task description when said position information
indicates that said mobile computer system is in a geographic
location that is within a selected range of a location at which a
task associated with said task description may be performed.
2. The computer assisted method of claim 1 wherein said database is
resident in said mobile computer system.
3. The computer assisted method of claim 1 wherein said database is
accessible via the Internet.
4. The computer assisted method of claim 1 wherein said task
description includes a geocode, said geocode corresponding to said
geographic location.
5. The computer assisted method of claim 4 wherein said task
description further includes a textual message and said step of
storing a task description comprises the steps of: entering said
textual message at a user terminal associated with said database;
associating said textual message with said geocode to produce said
task description; and saving said task description in said
database.
6. The computer assisted method of claim 5 wherein said positioning
information is received from one or more sources of pseudorandom
sequence signals containing information indicative of the location
of said one or more sources.
7. The computer assisted method of claim 6 wherein at least one of
said sources is a Global Positioning System (GPS) satellite.
8. The computer assisted method of claim 6 wherein one of said
sources is a pseudolite.
9. The computer assisted method of claim 6 wherein one of said
sources is a GLONASS satellite.
10. The computer assisted method of claim 5 wherein said
positioning information is received from a GPS receiver.
11. The computer assisted method of claim 5 wherein said step of
receiving positioning information comprises: collecting positioning
signals at an antenna associated with said mobile computer system;
downconverting said positioning signals from an RF frequency to an
IF frequency to generate downconverting positioning signals; and
extracting from said downconverting positioning signals said
positioning information.
12. The computer assisted method of claim 11 wherein said
positioning information comprises a latitude and a longitude.
13. The computer assisted method of claim 12 further comprising the
step of alerting a user that said mobile computer system is in said
geographic location after said step of indexing.
14. The computer assisted method of claim 13 wherein said step of
alerting comprises playing out a voice message through a voice
synthesizer associated with said mobile computer system.
15. The computer assisted method of claim 13 wherein said step of
alerting comprises displaying an alert message on a display
associated with said mobile computer system.
16. The computer assisted method of claim 13 wherein said mobile
computer system is integrated in a vehicle.
17. The computer assisted method of claim 16 wherein said step of
alerting comprises playing out a voice message through an audio
system associated with said vehicle.
18. The computer assisted method of claim 16 wherein said step of
alerting comprises displaying an alert message on a graphical
display system associated with said vehicle.
19. The computer assisted method of claim 18 wherein said graphical
display system includes a heads up display and said alert message
is displayed on said heads up display.
20. The computer assisted method of claim 13 wherein said step of
alerting comprises displaying said textual message on a display
associated with said mobile computer system.
21. A computer assisted method of using a geocoded database,
comprising the steps of: transporting a mobile computer system to a
first location having first geographic coordinates at a first time;
receiving and processing at said mobile computer system a first set
of RF signals including pseudorandom sequences containing
information indicative of the location of a source of said first
set of RF signals to derive said first geographic coordinates;
associating said first geographic coordinates with a descriptor
indicative of said first location in a database so as to form a
geocoded entry in said database; and associating a task to be
accomplished at said first location with said geocoded entry in
said database.
22. The computer assisted method of claim 21 further comprising the
steps of: transporting said mobile computer system to a second
location having second geographic coordinates at a second time;
receiving and processing at said mobile computer system a second
set of RF signals including pseudorandom sequences containing
information indicative of the location of a source of said second
set of RF signals to derive said second geographic coordinates;
analyzing said second geographic coordinates to determine whether
said second location is within a predetermined range of said first
location; and alerting a user of said mobile computer system of
said task if said second location is within said predetermined
range of said first location, otherwise not alerting said user of
said task.
23. The computer assisted method of claim 22 wherein said step of
alerting comprises displaying an alert message on a display
associated with said mobile computer system.
24. The computer assisted method of claim 23 wherein said alert
message comprises a text message descriptive of said task and said
step of displaying comprises scrolling said text message on said
display.
25. The computer assisted method of claim 22 wherein said step of
alerting comprises playing back a voice message descriptive of said
task through voice synthesizing means associated with said mobile
computer system.
26. The computer assisted method of claim 25 wherein said voice
synthesizing means includes a vehicle audio system.
27. A mobile computer system, comprising: a location determination
unit configured to receive and process RF signals including
pseudorandom sequences indicative of the location of a source of
said RF signals to derive a set of location coordinates
corresponding to the location of said mobile computer system; a
database coupled to said location determination unit including
location coordinates indicative of a location of interest; and a
database interface configured to access said database according to
the location of said mobile computer system.
28. A mobile computer system as in claim 27 wherein said database
is stored on a computer readable media.
29. A mobile computer system as in claim 28 wherein said computer
readable media is a disk.
30. A mobile computer system as in claim 28 wherein said computer
readable media is a CD-ROM.
31. A mobile computer system as in claim 28 wherein said computer
readable media is an EPROM.
32. A mobile computer system as in claim 28 wherein said database
further includes a task descriptor associated with said location
coordinates indicative of said location of interest.
33. A mobile computer system as in claim 32 wherein said task
descriptor comprises a text message.
34. A mobile computer system as in claim 32 wherein said task
descriptor comprises a voice message.
35. A mobile computer system as in claim 27 wherein said location
determination unit comprises a GPS server configured to provide
said location coordinates to said database interface across a
computer bus interconnecting said GPS server and said database
interface.
36. A mobile computer system as in claim 35 wherein said database
interface comprises a microprocessor configured to access said
database.
37. A mobile computer system as in claim 36 wherein said mobile
computer system is integrated in a vehicle.
38. A mobile computer system as in claim 37 wherein said database
includes a task descriptor associated with said location
coordinates.
39. A computer readable media on which is stored a data structure,
said data structure comprising a location reference and an
associated geocode, said geocode representing a geographic location
of said location reference.
40. A computer readable media as in claim 35 wherein said data
structure further comprises a task description associated with said
location reference.
41. A computer assisted method of scheduling a task, comprising the
steps of: storing, over a period of time, commute information
indicative of a regularly travelled route of a vehicle, said
commute information comprising one or more position information
entries, each position information entry derived from positioning
information received from a GPS receiver; storing one or more
vehicle stop entries for said vehicle, each vehicle stop entry
being associated with a location at which a task is performed, each
vehicle stop entry including positioning information received from
said GPS receiver; associating with said vehicle stop entries, task
descriptions, each task description being indicative of a task
capable of being accomplished at a location associated with an
associated vehicle stop entry; and retrieving one of said task
descriptions using first positioning information received from said
GPS receiver when said first positioning information indicates that
said vehicle will be in a first location within a predefined range
of one of said locations associated with one of said vehicle stop
entries, wherein said first positioning information is used in
conjunction with said commute information to determine that said
vehicle will be in said first location.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to real time
positioning systems and, more particularly, to the use of such
systems to control access to computer databases to assist in task
scheduling.
BACKGROUND
[0002] 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
configured to operate with Global Positioning System (GPS)
receivers as described in U.S. 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.
[0003] 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 transmits two coded
L-band carrier signals which enable some compensation for
propagation delays through the ionosphere. 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
satellites which are sufficiently 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.
[0004] 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 projection. By using
carrier phase differences in any one of several known techniques,
the antenna coordinates can be determined to an accuracy on the
order of .+-.1 cm.
[0005] Although U.S. 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
[0006] 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 geographic 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.
[0007] 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 messages 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.
[0008] A second embodiment provides a computer assisted method of
using a geocoded database. In this embodiment, a mobile computer
system is transported to a first location having first geographic
coordinates at a first time. At the first 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 first location. The geographic
coordinates of the first location are associated with a descriptor
indicative of the first 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 first location is
similarly associated with the geocoded entry in the database.
[0009] The mobile computer system is transported to a second
location at a second time and RF signals containing information
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 first 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
first location, on a display associated with the mobile computer
system.
[0010] A further embodiment provides a mobile computer system
having a location determination unit configured 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 coordinates
indicative of a location of interest and a database interface unit
configured to access the database according to the location of the
mobile computer system.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The present invention is illustrated by way of example and
not limitation in the figures of the accompanying drawings in
which:
[0012] FIG. 1 illustrates a digital system configured with a mobile
computer system, a location determination unit and a database
according to one embodiment; and
[0013] FIG. 2 illustrates a vehicle configured in accordance with
the present invention located near a pick-up location.
DETAILED DESCRIPTION
[0014] The following description of a position based personal
digital assistant sets forth numerous specific details in order to
provide a thorough understanding of the present invention. However,
after reviewing this specification, it will be apparent to those
skilled in the art that the present invention may be practiced
without some or all of these specific details. In other instances,
well known structures, programming techniques and devices have not
been described in detail in order not to unnecessarily obscure the
present invention.
[0015] 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 otherwise manipulated. It has proven convenient at
times, principally 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 convenient labels
applied to these quantities. Unless specifically 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 registers 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.
[0016] Referring to the accompanying Figure, 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 accompanying antenna
32.
[0017] 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, location 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.
[0018] 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).
[0019] Mobile computer system 20 typically includes a
microprocessor 21 and a system bus 22. Microprocessor 21 is 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 instructions 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).
[0020] 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 displayed 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 system to allow for playback of voice messages.
This arrangement 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.
[0021] 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 configured according to the protocol for
message exchange across the bus.
[0022] 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
simultaneously to all devices that are connected by the bus.
Several standards for such vehicle bus systems exist, for example,
the J1587 and J1708 specifications for bus systems published by the
Society of Automotive Engineers and the standards for communication
buses as set forth by the Society of Automotive Engineers and
Controller Area Network (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.
[0023] The J1587 (issued as 1988-01 and in revised form as
1994-01-10 and later revisions) and J1708 (issued as 1986-01 and in
revised form as 1990-10-05 and later revisions) specifications
recite standards and define 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
identification (MID) number (three digits from 0-255, with MIDs
0-127 being defined in J1708 and MIDs 128-255 defined in J1587);
(2) one or more measured parameter values associated with and
identified 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.
[0024] 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.
[0025] 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.
[0026] Second, the GPS data can be provided at a central server,
and any device (such as mobile computer system 20) requiring 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 flexible 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 individual client
use. Related GPS data may include GPS receiver health, GPS receiver
correction status, vehicle tracking status and other similar
information. Information 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.
[0027] 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.
[0028] The manner in which GPS processing is accomplished is well
known in the art. Briefly, GPS receivers normally determine their
position by computing relative times of arrival of signals
transmitted simultaneously from a multiplicity 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 pseudoranges which are simply the time delays
measured between the received signal from each satellite and a
local clock.
[0029] Many GPS receivers utilize correlation methods to compute
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 filters,
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 relative 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.
[0030] 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 between its geographic coordinates and those of mobile
computer system 20. Also, the positioning information provided by
location determination unit 30 may be enhanced through the use of
DGPS techniques as is common in the art.
[0031] 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
configured to provide appropriate electrical coupling to a bus
interconnecting the various vehicle systems.
[0032] As mentioned above, database 10 is preferably a geocoded
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 program 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".
[0033] 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 GROCERY 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.
[0034] 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 maintained 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
communication 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 the
Figure 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.
[0035] 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 location 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 satisfied, 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.
[0036] Once mobile computer system 20 has received the
above-mentioned geographic location coordinates (or other
positioning information) provided by location determination unit
30, microprocessor 21 will use this information to index database
10. Recall that database 10 contains a task description 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 description.
[0037] Now, microprocessor 21 uses current positioning information
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 receives current positioning information
from location determination unit 30 which indicates that mobile
computer system 20 (i.e., the user) is within a predetermined range
"R" (e.g., 100-1600 meters) of the grocery store, the "PICK UP
MILK" task description will be retrieved from database 10. This
task description (which may also have an associated audio alarm or
message) can be visually and/or audibly displayed over display 26
to alert the user that he or she is in close proximity to the
grocery store and should go pick up some milk. This feature can be
enhanced by displaying a map (using information stored in Mem 24 or
database 10) showing the user's current position (based on the
location information provided by location determination unit 30)
and the location of the grocery store (using the geocode
information associated with the stored task description or location
reference), thus allowing the user to navigate a route to the
grocery store.
[0038] In the above description, the database 10 is a database
programmed by the mobile computer system 20 user. However, database
10 may be provided as a unit by a commercial vendor. For example,
database 10 may be sold as an "Electronic Yellow Pages" on CD ROM
or other computer readable format for use by a variety of mobile
computer systems 20. In such cases, database 10 may be an Internet
Web Page or other resource. Regardless of its physical (or virtual)
configuration, database 10 includes geocoded references for a
variety of business establishments and other locations (such as
historical points of interest, stadiums, theaters, etc.) and is
accessible by calendaring, scheduling and/or other application
programs running on mobile computer system 20.
[0039] Alternatively, database 10 may originate as a commercially
purchased unit as described above and may be customized by a user
through use. For example, database 10 may have an associated
application program which "learns" a user's commute and purchasing
habits, for example, by analyzing electronic checkbook and/or other
electronic account records and associating those entries with
commute patterns derived from position information provided by
location determination unit 30. Such a database could be used to
prompt a user to make regular purchases (e.g., milk) or deliveries
when mobile computer system 10 is in an appropriate geographic
location without requiring the user to enter a specific task
description.
[0040] Such a geocoded database would also be useful for a user who
is new to a geographic area. For example, the user could purchase a
database 10 for a particular city of interest (for example, shortly
after moving to the city) and use the database to locate stores,
service providers, or other locations of interest. To illustrate,
suppose the user has just purchased a database 10 for ANY CITY and
wants to locate the nearest hardware store (to buy items for his or
her new home). By providing the mobile computer system 20 with
current positioning information from location determination unit 30
and entering a search query via user interface 25 seeking the
location of the nearest hardware store, microprocessor 21 could
access database 10 based on the positioning information and
retrieve and display a list of hardware stores having geocodes
which show the stores to be within a predetermined range (say a
mile or so) of the users current location. Upon selecting one of
the stores from the list, a map (also stored on the media
containing database 10) could be visually displayed showing the
user's present location and the relative location of the hardware
store.
[0041] In yet another embodiment, locations for anticipated vehicle
stops for a vehicle containing digital system 5 (or elements
thereof when database 10 is a remote unit) can be entered in
database 10 each day and/or periodically using user interface 25
and can also be entered on-the-fly by use of wireless
communications as discussed above. Such an embodiment may find use,
for example, in a package pick-up/delivery system or another system
where such information is useful. As the vehicle containing digital
system 5 follows a course, for example to allow for package
pick-up/delivery, mobile computer system 10 accesses database 10 to
determine upcoming pick-up/drop-off points. This information can be
accessed based on an order of priority or, preferably, based on the
location of the vehicle, as described above. In either case, the
location of upcoming pick-up/drop-off points can be displayed
visually and/or audibly on display 26. In addition, the present
location of the vehicle can be displayed using location information
provided by location determination unit 30. Such information may be
displayed as highlighted markers of a map or as a textual and/or
graphical list. For this and other embodiments, e.g., where
real-time traffic information is provided (either to a user or
directly to mobile computer system 20, for example, via wireless
transmissions), such a system may allow a user to determine and
navigate a "best route" to the next pick-up/drop-off point.
[0042] Although the methods and apparatus of the present invention
have been described with reference to GPS satellites, it will be
appreciated that the teachings are equally applicable to
positioning systems which utilize pseudolites or a combination of
satellites and pseudolites. Pseudolites are ground based
transmitters which broadcast a PN code (similar to a GPS signal)
modulated on an L-band carrier signal, generally synchronized with
GPS time. Each transmitter may be assigned a unique PN code so as
to permit identification by a remote receiver. Pseudolites are
useful in situations where GPS signals from an orbiting satellite
might be unavailable, such as tunnels, mines, buildings or other
enclosed areas. The term "satellite", as used herein, is intended
to include pseudolite or equivalents of pseudolites, and the term
GPS signals, as used herein, is intended to include GPS-like
signals from pseudolites or equivalents of pseudolites.
[0043] It will be further appreciated that the methods and
apparatus of the present invention are equally applicable for use
with the GLONASS and other satellite-based positioning systems. The
GLONASS system differs from the GPS system in that the emissions
from different satellites are differentiated from one another by
utilizing slightly different carrier frequencies, rather than
utilizing different pseudorandom codes. In this situation,
substantially all the circuitry and algorithms described above are
applicable, however, a receiver need only store a single PN code
for use during receive operations.
[0044] Thus, a position based personal digital assistant has been
described. In the foregoing specification, the present invention
has been described with reference to specific exemplary embodiments
thereof. It will, however, be evident that various modifications
and changes may be made thereto without departing from the spirit
and scope of the invention as set forth in the appended claims. The
specification and drawings are, accordingly, to be regarded in an
illustrative rather than a restrictive sense.
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