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Mobile Phone Patent Abstract
According to one embodiment of the invention, a mobile phone locator
is provided. The mobile phone locator includes a portable housing.
The mobile phone locator also includes a position locator positioned
at least partially in the portable housing. The position locator
is operable to determine a location by receiving information from
one or more satellites and to transmit a signal indicating the determined
location. The mobile phone locator also includes a converter positioned
in the portable housing and coupled to the position locator. The
converter is operable to convert the signal received from the position
locator into an output signal for the mobile phone. The output signal
is a non-speech, audible signal that is receivable by a microphone
of a mobile phone to be located. The mobile phone locator also includes
an output device positioned at least partially in the portable housing
and coupled to the converter. The output device is operable to send
the output signal to the mobile phone.
Mobile Phone Patent Claims
What is claimed is:
1. An apparatus for identifying the location of a mobile phone,
comprising: a housing coupled to a fastener, the fastener operable
to attach to a window of an automobile; a power management controller
positioned in the housing, the power management controller coupled
to a power source; an activation trigger positioned at least partially
in the housing, wherein the activation trigger sends an activation
command to the power management controller; a position locator positioned
at least partially in the housing, wherein the position locator
determines a location by receiving information from one or more
satellites and transmits a digital signal indicating the determined
location, the position locator coupled to the power management controller;
a visual indicator positioned at least partially in the housing
and coupled to the position locator; a converter positioned in the
housing and coupled to the position locator, wherein the converter
converts the digital signal received from the position locator into
a dual tone multi frequency audio signal indicating the determined
location; and a speaker positioned at least partially in the housing
and coupled to the converter, wherein: the speaker outputs the dual
tone multi frequency audio signal indicating the determined location;
the dual tone multi frequency audio signal comprises a latitude
group, a longitude group, and a velocity group; the latitude group,
the longitude group, and the velocity group each comprise a respective
delimiter; a first tone represents a delimiter associated with the
latitude group; a second tone represents a delimiter associated
with the longitude group; and a third tone represents a delimiter
associated with the velocity group.
2. The apparatus of claim 1, wherein the power source is a solar
panel that is attached to a surface of the housing.
3. The apparatus of claim 1, and further comprising an impact sensor
positioned in the housing and coupled to the power management controller,
wherein the impact sensor senses an impact and in response, automatically
initiates the determination of the location by the position locator.
4. The apparatus of claim 1, wherein the power management controller
assumes a sleep mode for power conservation.
5. The apparatus of claim 1, and further comprising a data storage
unit coupled to the position locator, wherein the position locator
stores information indicating the determined location in the data
storage unit and initiates a display of the stored information after
the power management controller is activated.
6. The apparatus of claim 1, wherein the position locator: receives
satellite information identifying an area where the one or more
satellites are positioned; and using the satellite information,
searches for the one or more satellites within the area.
7. The apparatus of claim 1, wherein: the power source is a battery
having a power level; the position locator updates the determined
location, the updating performed after a configurable time period;
if the power level exceeds a configurable level, the configurable
time period is a first time period; and if the power level does
not exceed the configurable level, the configurable time period
is a second time period.
8. An apparatus for locating a mobile phone, comprising: a portable
housing; a position locator positioned at least partially in the
portable housing, wherein the position locator determines a location
of a mobile phone by receiving information from one or more satellites
and transmits a signal indicating the determined location; an impact
sensor positioned at least partially in the portable housing and
coupled to a processor; the processor positioned at least partially
in the portable housing, wherein the processor transmits a command
to the mobile phone to automatically dial a phone number associated
with an emergency agency; a converter positioned in the portable
housing and coupled to the position locator, wherein the converter
converts the signal received from the position locator into an output
signal for the mobile phone, wherein the output signal is a dual
tone multi frequency audio signal that is receivable by a microphone
of the mobile phone; and an output device positioned at least partially
in the portable housing and coupled to the converter, wherein the
output device sends the dual tone multi frequency audio signal to
the mobile phone, wherein: the dual tone multi frequency audio signal
comprises a latitude group, a longitude group, and a velocity group;
the latitude group, the longitude group, and the velocity group
each comprise a respective delimiter; a first tone represents a
delimiter associated with the latitude group; a second tone represents
a delimiter associated with the longitude group; and a third tone
represents a delimiter associated with the velocity group.
9. The apparatus of claim 8, and further comprising a solar panel
that is attached to a surface of the portable housing.
10. The apparatus of claim 8, wherein the impact sensor senses
an impact and automatically initiates the determination of the location
by the position locator.
11. The apparatus of claim 8, and further comprising a data storage
unit coupled to the position locator, wherein the position locator
stores information indicating the determined location in the data
storage unit and initiates a display of the stored information after
the position locator is activated.
12. The apparatus of claim 8, wherein the position locator: receives
satellite information identifying an area where the one or more
satellites are positioned; and using the satellite information,
searches for the one or more satellites within the area.
13. The apparatus of claim 12, wherein: the search lasts for a
configurable time period; if one satellite is found, the configurable
time period is extended by a first time period; if two satellites
are found, the configurable time period is extended by a second
time period; and if three satellites are found, the configurable
time period is extended by a third time period.
14. The apparatus of claim 8, and further comprising a cradle that
is attachable to a window of an automobile, wherein the cradle receives
the portable housing.
15. The apparatus of claim 8, and further comprising a cradle that
is attachable to a window of an automobile, the cradle comprising
a solar panel that is positioned to face the window when attached
to the window, wherein the cradle receives the portable housing
and electrically couples the solar panel to the position locator
positioned in the portable housing.
16. An apparatus for locating a mobile phone, comprising: a position
locator determining a location and generating a location signal
indicating the determined location; impact sensing means for sensing
an impact and in response, initiating the determination of the location
by the position locator; a conversion means for converting the location
signal into an output signal, wherein the output signal is a dual
tone multi frequency audio signal that is receivable by an input
unit of a mobile phone to be located; a transmission means for wirelessly
transmitting the dual tone multi frequency audio signal to the mobile
phone, wherein: the dual tone multi frequency audio signal comprises
a latitude group, a longitude group, and a velocity group; the latitude
group, the longitude group, and the velocity group each comprise
a respective delimiter; a first tone represents a delimiter associated
with the latitude group; a second tone represents a delimiter associated
with the longitude group; and a third tone represents a delimiter
associated with the velocity group; and means for packaging the
position locator, the impact sensing means, the conversions means,
and the transmission means as a single package that is attachable
to a window of an automobile.
17. The apparatus of claim 16, and further comprising means for
collecting solar energy coupled to the means for packaging the position
locator.
18. The apparatus of claim 16, and further comprising means for
transmitting a command to the mobile phone to automatically dial
a phone number associated with an emergency agency.
19. The apparatus of claim 16, and further comprising means for
storing data coupled to the position locator, wherein the position
locator stores information indicating the determined location in
the means for storing data and initiates a display of the stored
information after the position locator is activated.
20. The apparatus of claim 16, wherein the position locator: receives
satellite information identifying an area where the one or more
satellites are positioned; and using the satellite information,
searches for the one or more satellites within the area.
21. The apparatus of claim 16, wherein the input unit is a microphone.
22. The apparatus of claim 16, and further comprising a cradle
that is attachable to a window of an automobile, wherein the cradle
receives the means for packaging.
23. The apparatus of claim 16, and further comprising a cradle
that is attachable to a window of an automobile, wherein the cradle:
comprises a solar panel that is positioned to face the window when
attached to the window; and receives the portable housing and electrically
couples the solar panel to the position locator.
24. A mobile phone locator system comprising: a portable housing;
a cradle, wherein the cradle receives the portable housing and electrically
couples the portable housing to an external device, the cradle attachable
to a window of an automobile; an impact sensor positioned at least
partially in the portable housing, wherein the impact sensor activates
a position locator after sensing an impact; the position locator
positioned at least partially in the portable housing, wherein the
position locator determines a location by communicating with one
or more satellites and transmits a signal indicating the determined
location; a converter positioned in the portable housing and coupled
to the position locator, wherein the converter converts the signal
received from the position locator into an output signal for the
mobile phone, wherein the output signal is a dual tone multi frequency
audio signal that is receivable by a microphone of a mobile phone
to be located; and an output device positioned at least partially
in the portable housing and coupled to the converter, wherein the
output device sends the dual tone multi frequency audio signal to
the mobile phone, wherein: the dual tone multi frequency audio signal
comprises a latitude group, a longitude group, and a velocity group;
the latitude group, the longitude group, and the velocity group
each comprise a respective delimiter; a first tone represents a
delimiter associated with the latitude group; a second tone represents
a delimiter associated with the longitude group; and a third tone
represents a delimiter associated with the velocity group.
25. The system of claim 24, wherein the portable housing further
comprises a solar panel that is attached to a surface of the portable
housing.
26. The system of claim 24, and further comprising a solar panel
that is coupled to a cradle.
27. The system of claim 24, and further comprising a data storage
unit positioned in the portable housing and coupled to the position
locator, wherein the position locator stores information indicating
the determined location in the data storage unit and initiates a
display of the stored information after the position locator is
activated.
28. The system of claim 24, wherein the position locator: receives
satellite information identifying an area where the one or more
satellites are positioned; and using the satellite information,
searches for the one or more satellites within the area.
29. A method for locating a mobile phone, comprising: providing
an apparatus comprising: a portable housing; a position locator
positioned at least partially in the portable housing, wherein the
position locator determines a location by receiving information
from one or more satellites and transmits a signal indicating the
determined location; an impact sensor positioned at least partially
in the portable housing, wherein the impact sensor activates the
apparatus after sensing an impact; a converter positioned in the
portable housing and coupled to the position locator, wherein the
converter converts the signal received from the position locator
into an output signal for the mobile phone, wherein the output signal
is a dual tone multi frequency audio signal having an effective
range; and an output device positioned at least partially in the
portable housing and coupled to the converter, wherein: the output
device wirelessly transmits the dual tone multi frequency audio
signal to the mobile phone; the dual tone multi frequency audio
signal comprises a latitude group, a longitude group, and a velocity
group; the latitude group, the longitude group, and the velocity
group each comprise a respective delimiter; a first tone represents
a delimiter associated with the latitude group; a second tone represents
a delimiter associated with the longitude group; and a third tone
represents a delimiter associated with the velocity group; coupling
the apparatus to a window of a vehicle; and positioning an input
unit of the mobile phone within the effective range of the dual
tone multi frequency audio signal.
30. The method of claim 29, further comprising: automatically commanding
the mobile phone, using the apparatus, to establish a communication
channel to a predetermined location; and automatically transmitting
the output signal to the mobile phone for transmission to the predetermined
location.
31. The method of claim 30, wherein the predetermined location
is a call center that transmits the determined location indicated
by the output signal to an emergency service.
32. The method of claim 29, and further comprising automatically
transmitting an emergency signal indicating that an emergency has
occurred at the location indicated by the output signal.
33. The method of claim 29, wherein the apparatus further comprises
a solar panel that is attached to a surface of the portable housing.
34. The method of claim 29, and further comprising: receiving,
at the apparatus, satellite information identifying an area where
the one or more satellites are positioned; and searching, using
the satellite information, for the one or more satellites within
the area using the position locator.
Mobile Phone Patent Description
TECHNICAL FIELD OF THE INVENTION
This invention relates generally to the field of communications
and more particularly to a mobile phone locator.
BACKGROUND OF THE INVENTION
The Federal Communications Commission's ("FCC") enhanced
911 ("E911") initiative strives to improve the emergency
call service by providing a mobile telephone user's identification
and physical location during a call. To that end, the FCC issued
a mandate requiring the communications industry to modify the existing
wireless communications architecture and associated wireless phones
so that the wireless caller's location may be ascertained from a
designated Public Safety Answering Point ("PSAP"). This
feature is referred to as Automatic Location Identification ("ALI").
To date, and with widespread frustration in the wireless communications
industry, the introduction of ALI mobile phones has yet to materialize
in any significant way. Because of the technological difficulties
of modifying the existing communications architecture, FCC has extended
the deadline for compliance with the issued mandate at the request
of the wireless communications industry.
SUMMARY OF THE INVENTION
According to one embodiment of the invention, a mobile phone locator
is provided. The mobile phone locator includes a portable housing.
The mobile phone locator also includes a position locator positioned
at least partially in the portable housing. The position locator
is operable to determine a location by receiving information from
one or more satellites and to transmit a signal indicating the determined
location. The mobile phone locator also includes a converter positioned
in the portable housing and coupled to the position locator. The
converter is operable to convert the signal received from the position
locator into an output signal for the mobile phone. The output signal
is a non-speech, audible signal that is receivable by a microphone
of a mobile phone to be located. The mobile phone locator also includes
an output device positioned at least partially in the portable housing
and coupled to the converter. The output device is operable to send
the output signal to the mobile phone.
According to one embodiment of the invention, a method for locating
a mobile phone is provided. The method includes providing an apparatus
for locating a mobile phone. The apparatus is operable to determine
a location by receiving information from one or more satellites
and to wirelessly transmit an output signal indicating the determined
location. The output signal has an effective range. The method also
includes coupling the apparatus to a window of a vehicle. The method
also includes positioning an input unit of the mobile phone within
the effective range of the output signal.
Some embodiments of the invention provide numerous technical advantages.
Some embodiments may benefit from some, none, or all of these advantages.
For example, according to one embodiment, the location of a mobile
phone and its user may be ascertained at other locations, such as
a PSAP, without a massive overhaul of the existing communications
architecture or modification of the mobile phone. According to another
embodiment, the procedure that a user may be required to follow
to communicate the location of the user is simplified. According
to another embodiment, information concerning emergency situations
may be communicated to emergency agencies with a reduced level of
interaction by the user.
Other technical advantages may be readily ascertained by one of
skill in the art.
BRIEF DESCRIPTION OF THE DRAWINGS
Reference is now made to the following description taken in conjunction
with the accompanying drawings, wherein like reference numbers represent
like parts, in which:
FIG. 1 is a schematic diagram illustrating one embodiment of a
communications architecture that may benefit from the teachings
of the present invention;
FIG. 2 is a schematic diagram illustrating one embodiment of a
position locator of FIG. 1;
FIG. 3 is a schematic diagram illustrating one embodiment of a
cradle that may receive the position locator of FIG. 2;
FIG. 4A is a schematic diagram illustrating one embodiment of the
position locator of FIG. 2 placed on a window of a vehicle;
FIG. 4B is a schematic diagram illustrating one embodiment of the
position locator of FIG. 4A transmitting an output signal to a mobile
phone;
FIG. 4C is a schematic diagram illustrating one embodiment of the
position locator of FIG. 2 transmitting an output signal to a mobile
phone;
FIG. 4D is a schematic diagram illustrating one embodiment of the
position locator of FIG. 2 automatically transmitting an output
signal to a mobile phone in an emergency situation;
FIG. 5 is a schematic diagram illustrating additional details of
one embodiment of the position locator of FIG. 2;
FIG. 6 is a block diagram illustrating additional details of one
embodiment of the position locator of FIG. 2;
FIGS. 7A and 7B are flow charts illustrating one embodiment of
a method of determining a location of a mobile phone;
FIGS. 7C and 7D are flow charts illustrating one embodiment of
a method of power management and information update that may be
used in conjunction with the method of FIGS. 7A and 7B;
FIG. 7E is a flow chart illustrating one embodiment of a method
for using the position locator of FIG. 2 as an emergency notification
device;
FIG. 8A is a schematic diagram illustrating one embodiment of a
message that is transmitted as an output signal from the position
locator of FIG. 2; and
FIG. 8B is a schematic diagram illustrating one embodiment of a
message stream that is transmitted as an output signal from the
position locator of FIG. 2.
DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION
Embodiments of the invention are best understood by referring to
FIGS. 1 through 8B of the drawings, like numerals being used for
like and corresponding parts of the various drawings.
FIG. 1 is a schematic diagram illustrating one embodiment of a
communications architecture 10 that may benefit from some embodiments
of the invention. Communications architecture 10 comprises a wireless
communications network 5 that allows a mobile communications device
3 to communicate with others, such as an operator 7. In some embodiments,
the communication between mobile communications device 3 and operator
7 also passes through a call center 6 that manages and distributes
incoming and outgoing communications for operator 7.
Mobile communications device 3 may be any portable device that
allows a user to communicate with another party over network 5.
Examples of mobile communications device 3 include a cellular phone,
a personal digital assistant ("PDA"), a wireless email
device, a hand-held computer, or other devices or combination of
these devices. Mobile communications device 3 is referred to herein
as a mobile phone 3; however, mobile phone 3 may be any mobile communications
device.
Communications network 5 may include any network of communications
devices and channels that are operable carry communications signals
between two or more parties. For example, network 5 may include
antennae for transmitting and receiving wireless communication signals
to and from mobile phone 3. Network 5 may also include the internet,
various intranets, ethernet networks, wireless telephone systems,
and plain old telephone systems ("POTS").
Call center 6 may be a system or an organization that manages calls
to and from operator 7. For example, call center 6 may comprise
one or more banks of computers (not explicitly shown) that automatically
route calls from network 5 based on protocols that are set up using
advanced intelligent network ("AIN"). Call center 6 may
also comprise a switchboard operated by persons or computers that
may be used to route calls based on a set of rules. For example,
call center 6 may be an emergency call center that receives "911"
emergency calls and routes the calls to operators 7 of emergency
agencies, such as fire stations, that are located closest to the
respective origins of the "911" calls. Call center 6 may
also be a Public Safety Answering Point ("PSAP") that
is established as a part of the enhanced 911 ("E911")
initiative by the Federal Communications Commission ("FCC").
Mobile phone 3 is required to have Automatic Location Identification
("ALI") capability in the future under the E911 initiative.
ALI refers to the capability of mobile phone 3 to transmit its location
data to a third party, such as a PSAP. To provide mobile phone 3
with ALI capability, the wireless industry is pursuing two fundamental
approaches and a third hybrid technique: 1) Global Positioning System
("GPS") enabled handset, 2) a network-based solution and
3) a network assisted GPS approach. All three approaches have significant
technical and economic challenges.
The GPS handset method has difficulty working indoors because of
the very weak satellite signals. GPS antenna location and orientation
are critical for proper GPS operation. However, even state of the
art GPS receivers have problems with reception in automobiles because
of the metal roof. Obstructions between the satellites and the antenna
and poorly directed antennas (with respect to the sky) are two major
causes for satellite signal acquisition failure. For GPS enabled
handsets, the control of these factors are in the hands of the user.
However, there is a high probability of satellite signal acquisition
failure when a panic-stricken user is moving about during the call
and unaware of the GPS acquisition idiosyncrasies. This especially
problematic because strong GPS signals are more critical for initial
satellite acquisition than for subsequent tracking. Additionally,
today's GPS receivers require too much power for operation for the
GPS receivers to be left operating the entire time the phone is
on. In fact, some consume more power than the mobile phone itself.
So the current strategy is to intermittently power the GPS receiver
in the mobile phone on an as-needed basis to conserve battery life.
Although a power management scheme conserves the battery of a phone,
it also requires the GPS receiver to power up (cold start) and reacquire
ephemeris data before it can determine a location. A cold-start
position fix can easily take 45 seconds or more, even with today's
premium grade GPS receivers. Further, for every cold start, the
user is required to hold the phone in an optimal position (outdoors)
long enough to acquire the necessary signals.
The network-based solution requires a very precise system timing
over the wireless network(s) because GPS is not used. In place of
GPS, three or more time-difference-of-arrival ("TDOA")
measurements of a mobile phone's signal are measured by cell sites
and used to triangulate the location of the phone. To meet the E911
accuracy mandate, nanosecond system timing is required along with
large amounts of control data across the network. Furthermore, there
is a multitude of independently operating wireless technologies,
such as Advanced Mobile Phone Service, Code Division Multiple Access,
Time Division Multiple Access, Global System for Mobile communication,
and Integrated Digital Enhanced Network, which adds to the complexity
and magnitude restructuring the existing network to implement this
approach.
The network assisted GPS ("AGPS") technique involves
enhancements to both mobile phone 3 and the supporting wireless
network 5. AGPS attempts to overcome the initial satellite acquisition
problem by receiving current ephemeris data from a central wireless
network server, taking a data snapshot of all the satellites in
view based on the ephemeris data it received and sending the snapshot
back to the central wireless network server. The navigation solution
is then computed by the server and sent back to the mobile phone.
This approach requires significant changes to the wireless infrastructure.
Large amounts of control data will have to traverse the network.
Further, each of the wireless technologies operating today would
have to develop their own data delivery mechanism. All of these
add to the complexity and cost of modifying the existing network
infrastructure.
According to some embodiments of the present invention, an apparatus,
system and method are provided that allow the determination of a
phone's location without any modification to a supporting wireless
network or positioning a GPS device within the mobile phone. This
is advantageous in some embodiments of the invention because the
cost and effort of modifying a mobile phone, a wireless network,
or both, may be avoided. According to another embodiment, the procedure
that a user may be required to follow to communicate the location
of the user is simplified. According to another embodiment, information
concerning emergency situations may be communicated to emergency
agencies with reduced level of interaction by the user. Additional
details of example embodiments of the invention are described in
greater detail below in conjunction with portions of FIG. 1 and
FIGS. 2 through 8B.
Referring back to FIG. 1, a position locator 1 is provided for
use in conjunction with a mobile phone, such as mobile phone 3;
however, position locator 1 may also be used in conjunction with
any communication device, such as a radio or a conventional telephone.
Position locator 1 is operable to determine a location by receiving
information from one or more satellites and to wirelessly transmit
an output signal indicating the determined location. In one embodiment,
position locator 1 includes a Location Determination System (LDS)
receiver operable to work in conjunction with a system 2, such as
the Global Positioning System (GPS) or Glonass, to determine a location.
GPS system 2 is used herein as an example of system 2; however,
other location determination systems may also be used. In one embodiment,
a physically separate mobile phone 3 of any type is used to place
an emergency or other service request call and then positioned near
locator 1 by the user so that an emanating output signal 4, such
as acoustic tone, encoded with the coordinate data may be transferred
to mobile phone 3. In one embodiment where output signal 4 is acoustic
tone, signal 4 is sent over wireless telephone network 5 on the
voice path to call center 6 where the call is then routed to operator
7. In some embodiments, operator 7 may be physically located in
call center 6. The encoded tones are decoded either at call center
6 or by a computer accessible to operator 7 and the caller's location
is presented on a computer screen, for example. In another embodiment,
output signal 4 may be in other formats, such as radio frequency
("RF") or infrared signals. One example of infrared signal
format is the IrDA standard.
FIG. 2 is a schematic diagram of one embodiment of position locator
1. In one embodiment, locator 1 is approximately the same length
and width as a credit card and slightly thicker than a credit card;
however, locator 1 may have other physical dimensions. In one embodiment,
locator 1 may be attached to a vehicle window, such as a windshield,
with hook-and-loop fastening strips, such as Velcro.RTM.; however,
other fastening devices, such as adhesives or suction cups may be
used. In one embodiment, position locator 1 may comprise an activation
trigger 9 that may be used to initiate locator 1 to determine a
location and transmit output signal 4 indicating the determined
location. In one embodiment, activation trigger 9 may be used to
repeat the transmission of output signal 4 if locator 1 is already
activated.
In one embodiment, a visual indicator 10, such as a Light Emitting
Diode ("LED") 10, is also included and may be illuminated
during the operation of locator 1 to indicate the progress and success
of satellite acquisition of the location coordinates. In embodiments
where output signal 4 is acoustic tone, an audio speaker 11 may
be included as an output device 11 of signal 4. Speaker 11 may be
used to produce progress tones for the satellite acquisition sequence
as well as the signaling tones containing the coordinate data. In
one embodiment, additional information, such as vehicle speed, altitude,
and call type, may also be transmitted using output device 11. A
connector 8 may be included in some embodiments of locator 1 to
provide an external power/charging connection from power sources,
such as vehicle power or a solar panel and may also include connections
for a serial data port. Additional details of these and other components
of locator 1 is described below in conjunction with FIGS. 5 and
6.
In one embodiment, connector 8 may be used to provide GPS data
in industry standard NMEA0183 format to a personal digital assistant
("PDA") or a laptop computer with suitable navigation
software. Connector 8 may also route information from a computer
mapping program, for example, to be downloaded into position locator's
1 memory and subsequently used to enunciate turn-by-turn directions
to a driver during travel. Connector 8 may also be used to update
position locator's 1 software or to upload trip log information.
FIG. 3 is a schematic diagram illustrating one embodiment of a
cradle 12 that may receive position locator 1. Cradle 12 may comprise
a fastener (not explicitly shown) that is operable to couple cradle
12 to a window of a vehicle. An example of a fastener is double-sided
adhesive tape, which is not explicitly shown in FIG. 3. In one embodiment,
cradle 12 may also comprise an external power/data port connection
14, which may be wired into a vehicle's twelve-volt power source.
In one embodiment, connection 14 may be wired to a vehicle's power
source by routing wires 13 over the vehicle's headliner and to the
dome, map or visor light circuits, or down to the fuse panel below
the dash. In one embodiment, cradle 12 may also comprise a solar
panel 33 that is positioned to face skyward, eliminating the need
for any wiring. In another embodiment, solar panel 33 may also be
positioned on a face of a housing for position locator 1 or cradle
12.
In one embodiment, position locator 1 may slide into place within
cradle 12, as shown in FIG. 3, and is retained by a clip 15; however,
other ways of securing locator 1 may also be used. Depressing clip
15 allows the user to slide locator 1 back out of cradle 12 for
portable use away from the vehicle. In one embodiment, when locator
1 is fully inserted into cradle 12, electrical connection is made
between connector 8 and connector 14.
FIG. 4A is a schematic diagram illustrating one embodiment of position
locator 1 that is placed on a window, such as a windshield 16, of
a vehicle 17; however, a window may be other transparent or translucent
surface of vehicle 17, such as the back window or side windows.
The embodiment of mounting method shown in FIG. 4A allows a GPS
antenna of position locator 1 to have an unhindered view of the
sky, which is advantageous because such positioning increases the
probability of determining a location faster. Position locator 1
may also be positioned in other parts of vehicle 17. For example,
position locator 1 may be placed on the dashboard of vehicle 17
or built into the instrument console of vehicle 17. In some embodiments
where position locator 1 is built into the instrument console, position
locator 1 may be coupled to an external GPS antenna.
FIG. 4B is a schematic diagram illustrating one embodiment of position
locator 1 transmitting output signal 4 to mobile phone 3. Output
signal 4 may be in acoustic, infrared, or any other suitable format.
When using position locator 1 in vehicle 17, in one embodiment,
mobile phone 3 is brought within an effective range of output signal
4 so that output signal 4 may be received by an input unit 3A of
mobile phone 3. An example of input unit 3A may be a microphone
3A; however, other input units, such as an infrared receiver, may
be used. In one embodiment where output signal 4 is in an acoustic
format, such as dual tone multi frequency ("DTMF") audio
signal, microphone 3A may receive output signal 4 and send the output
signal 4 over a voice channel that has been established by mobile
phone 3.
FIG. 4C is a schematic diagram illustrating one embodiment of using
position locator 1 away from vehicle 17. In the embodiment shown
in FIG. 4C, position locator 1 is placed on a flat surface, such
as the ground or a table top, so that position locator 1 has a good
view of GPS satellites 120. Once locator 1 has received the necessary
information from GPS satellites 120, locator 1 determines its own
position and transmits output signal 4. In the embodiment shown
in FIG. 4A, output signal 4 is an infrared beam in a format such
as the IrDA standard; however, other signaling formats, such as
DTMF or RF may also be used. A user places mobile phone 3 within
the effective range of output signal 4 so that output signal 4 is
picked up by input unit 3A of mobile phone 3.
FIG. 4D is a schematic diagram illustrating one embodiment of position
locator 1 automatically transmitting output signal 4 to mobile phone
3 in an emergency situation, such as an automobile accident. In
one embodiment, position locator 1 comprises an impact sensor, which
is described below in greater detail in conjunction with FIGS. 5
and 6. When vehicle 17 is involved in a collision, the impact sensor
senses the impact and automatically initiates a determination of
the location of position locator 1. In one embodiment, mobile phone
3 and position locator 1 may each have a transceiver chip that may
be used to establish a short-range, wireless connection using Bluetooth.TM..
After the impact sensor senses the impact, it may initiate a transmission
of output signal 4 indicating a command for mobile phone 1 to activate
itself and dial a phone number associated with an emergency agency,
such as a PSAP or a police station. The impact sensor may also initiate
a transmission of output signal 4 that indicates the determined
location of position locator 1. This is advantageous in some embodiments
of the invention because, in emergencies where a user may not be
able to call for help, position locator 1 may be used in conjunction
with mobile phone 3 to automatically call for help.
FIG. 5 is a schematic diagram illustrating one embodiment of a
layout of position locator's 1 components. In one embodiment, position
locator 1 comprises a housing 1A, an activation trigger 9, an impact
sensor 19, visual indicator 10, output device 11, a power source
20, connector 8, an amplifier 21, a power management controller
29, a GPS receiver 22, a processor 23, and GPS antenna 24. Housing
1A may be formed from any suitable material, such as plastic. In
one embodiment, housing 1A may be shaped like a card; however, housing
1A may be in any other suitable shape. An example of activation
trigger 9 is a button; however, any device that allows a user to
provide input to position locator 1 may be activation trigger 9.
An example of visual indicator 10 is an LED; however, any other
device that is operable to visually signal a user may be visual
indicator 10. Output device 11 may be any device operable to transmit
output signal 4. For example, where output signal 4 is DTMF, output
device 11 may be a speaker. Where output signal 4 is in a electromagnetic
or infrared format, output device 11 may be an antenna or a bluetooth
transceiver chip. Power source 20 may be any source of electrical
power. For example, power source 20 may be a battery. In some embodiments
where power is provided from an external source, such as solar panel
15, power source 20 may be a rechargeable battery. In some embodiments
where power is provided from an external source, such as a vehicle's
17 twelve-volt power source, power source 20 may be omitted. In
some embodiments, the arrangement of components may be varied, as
determined by one skilled in the art. In some embodiments, more
or less components may be required. For example, impact sensor 19
and/or visual indicator 10 may be omitted in some embodiments.
FIG. 6 is a block diagram illustrating additional details of position
locator 1 shown in FIG. 5. A GPS patch antenna 24 is coupled to
GPS receiver 22 through a line 25. In one embodiment, antenna 24
and receiver 22 may be of conventional design and are commercially
available; however, any antenna and receiver for determining a location
may be used. An example of GPS receiver 22 is Axiom Swift.TM. series
GPS receivers available from Axiom Navigation. In one embodiment,
processor 23 may be an integral part of GPS receiver 22 and comprises
a timer 26 and memories 27 and 41. Memories 27 and 41 may be used
to store the personal locator firmware. In one embodiment, power
source 20 is a 3.6 volt battery (re-chargeable or non-rechargeable)
and may be coupled via a line 30 to power management controller
29; however, any suitable power source may be used as power source
20. An example of power management controller 29 is Maxim MAX1773.TM.,
available from Maxim. Power is fed via a line 28 to GPS receiver
22, processor 23, memories 27 and 41 and timer 26.
Processor 23 is connected to an output module 100. In one embodiment,
output module 100 comprises a converter 42, an amplifier 21, and
output device 11. An example of converter 42 is an 8-bit Digital-to-Analog
converter ("DAC"), such as the Maxim MAX5383.TM., available
from Maxim. Although DAC 42 is used as an example of converter 42,
any device that converts signals from processor 23 into a particular
format of output signal 4 may be used. For example, converter 42
may convert signals from processor 23 into a beam of infrared signal
rather than acoustic tones. Converter 42 is coupled to processor
23 via lines 44. In one embodiment, the converted signal from converter
42 is transmitted to the input of amplifier 21 via a line 43. The
amplified signal of amplifier 21 is transmitted to output device
11 via line 45. In one embodiment where output signal 44 is in DTMF
format, an example of amplifier 21 is a conventional dual audio
amplifier design with a rating of approximately 250 mW per channel,
such as the National Semiconductor LM4880.TM. available from National
Semiconductor.
In one embodiment, because the voltage of power source 20 is only
3.6V and in order to achieve higher voltage swings at speaker 11,
a dual amplifier is used as amplifier 21 and inputs are driven 180
degrees out of phase. Further, amplifier differential output 45
drives both sides of speaker 11. In one embodiment, driving speaker
11 as described above rather than driving only one side of speaker
11 and grounding the other side results in higher output power and
therefore higher acoustical energy. In one embodiment, processor
23 uses a control line 46 to turn converter 42 and amplifier 21
on and off as needed.
Although one embodiment of output module 100 is described above,
output module 100 may comprise other components depending on the
particular format of output signal 4 that is required. For example,
output module 100 may comprise a transceiver (not explicitly shown)
for sending wireless signals in Bluetooth.TM. format. The details
concerning the conversion of signals from processor 23 into another
format, such as the Bluetooth.TM. format, are well known by one
skilled in the art.
Referring back to FIG. 6, a line 37 of power management controller
29 may be used to transmit an indication to processor 23 that power
source 20 needs replacement or recharging. In some embodiments where
power management controller 29 is operable to assume a sleep mode,
timer 26 may periodically wake up processor 23 (every 5 minutes
for example) and check for signals transmitted over line 37. If
processor 23 determines that power level is low, processor 23 may
initiate a signal to the user indicating that the power level is
low. For example, processor 23 may initiate a transmission of a
tone or synthesize an audible phrase through output device 11, indicating
the battery condition. In one embodiment, processor 23 may accomplish
this by turning on converter 42 and audio amplifier 21 via line
46 and reading sound waveform data from a table stored in memory
27. Then processor 23 transmits the sound waveform data via serial
port 44 which, in turn, drives converter 42. Converter 42 converts
the received signals into analog signals in accordance with the
data transmitted over line 44 and transmits the converted analog
signals to amplifier 21 over line 43. Output device 11 receives
the amplified analog signals over line 45. Other methods of informing
a user that power level is low may also be used, as determined by
one skilled in the art.
In one embodiment, when operating on power source 20 that is internal,
personal locator 1 may assume a sleep state. A "sleep state"
or a "sleep mode" refers to drawing only enough power
to operate timer 26 and retain the most recent GPS almanac and ephemeris
data in memory 27. Activation trigger 9 is coupled to power management
controller 29 via a line 35 and when depressed, triggers power management
controller 29 to wake up processor 23. Processor 23 in turn wakes
up GPS receiver 22 and begins searching for satellites 120. In one
embodiment, as the search progresses, visual indicator 10 is made
to blink periodically, indicating the number of satellites in view
and the eventual acquisition of the coordinates. Processor 23 controls
visual indicator 10 via a line 40. In one embodiment, processor
23 may also initiate an audible indication of the search progress
using output module 100.
In one embodiment, impact sensor 19 is coupled to power management
controller 29 using line 36. If impact sensor 19 detects g-forces
above a predetermined threshold (during an accident, for example),
impact sensor 19 is operable to initiate an activation of processor
23 via a line 36. For example, impact sensor 19 may signal power
management controller 29 to apply power to processor 23 via power
path 28. In one embodiment, this automatically initiates the location
determination process following the accident, giving locator 1 a
head start in acquiring satellite information instead of waiting
for the occupant to recover enough from the accident to manually
activate locator 1. In one embodiment where output module 100 is
operable to transmit wireless Bluetooth.TM. format output signal
4, processor 23 may respond to the impact signal from impact sensor
19 by automatically sending output signal 4 to mobile phone 3 indicating
a command to establish a communication path to a predetermined location.
Examples of a predetermined location include a PSAP, police station,
hospital, fire station, or any other emergency service, agencies.
Processor 23 may also send a command to mobile phone 3 to inform
the predetermined location that an emergency event has occurred.
Processor 23 may also automatically initiate the determination of
the location and send output signal 4 indicating the determined
location to mobile phone 3 for routing the information of the determined
location to the predetermined location. In one embodiment, more
than one predetermined locations may be contacted by mobile phone
3. For example, in response to the impact signal from impact sensor
19, processor 23 may command mobile phone 3 to dial all emergency
services and the home of the user.
Referring again to FIG. 6, in one embodiment, external power may
be provided from sources such as vehicle power or solar power using
lines 32 and 33, respectively. In one embodiment, these inputs are
coupled to a charging circuit 31 and then to power source 20 over
a line 34. In another embodiment, external power input may be provided
directly to power management controller 29. An example of charging
circuit 31 is Maxim MAX1776.TM.. In one embodiment where external
power is provided, GPS receiver 22 and processor 23 remain activated
rather than assuming a sleep mode. GPS receiver 22 and processor
23 continuously track satellites 120 and update memory 41 with the
latest coordinates as well as almanac and ephemeris data. Furthermore,
this data may be logged into memory 27 where it can be retrieved
at a later time via a data port 39. When operating from external
power, the activation of personal locator 1 may produce output signal
4 immediately if the current location has already been determined.
In one embodiment, processor 23 performs these and other functions
described above by executing a program 23A. In some embodiments,
program 23A may be stored in memory 41; however, other data storage
units may be used to store program 23A or any other data associated
with program 23A.
FIGS. 7A and 7B are flow charts illustrating one embodiment of
a method 130 of determining a location of mobile phone 3. FIGS.
7A and 7B are described jointly in conjunction with FIG. 6. Some
or all of method 130 may be performed by processor 23 that is executing
program 23A and/or power management controller 29. Method 130 starts
at step 47. At step 48, whether an activation event has occurred
is determined. In one embodiment, pressing a button serving as activation
trigger 9 may be an activation event of step 48; however, other
activation events, such as a signal from impact sensor 19, may be
an activation event. If no activation event has occurred, then the
"no" branch is followed to step 49 where a test is performed
to determine if there is external power available, such as vehicle
power. If external power is present, then processor 23 and GPS receiver
22 are activated and method 130 proceeds to step 67, which is described
below in conjunction with FIG. 7B. If there is no external power
present, the power level of internal power source 20 is checked
at step 52. If the battery level is acceptable, method 130 loops
back to step 48. If, however, battery 20 determined to be low at
step 52, then method 130 proceeds to step 55 where a signal indicating
the level of available power is transmitted to a user. For example,
a synthesized phrase such as "BATTERY LOW" may be enunciated
or a short beep can be emitted, followed by a return to step 48.
Referring again to step 48, if an activation event has occurred,
method 130 proceeds to step 50 where power management controller
29 activates GPS receiver 22 and processor 23. The activation of
GPS receiver 22 and processor 23 initiates GPS receiver and processor
23 to begin searching for satellites 120. Method 130 then proceeds
to step 54 where a test is performed by processor 23 to determine
if location coordinates have been acquired. If no coordinates have
been determined, method 130 proceeds to step 57 where the elapsed
time since the activation at step 50 is determined. If GPS receiver
22 and processor 23 have been on for less than a predetermined time
period (3 minutes, for example), method 130 continues to step 53
where processor 23 initiates a transmission of a signal to the user
indicating the progress of the satellite search. For example, short
audible beeps and/or blinks from visual indicator 10 may indicate
to the user that locator 1 is in the process of searching for satellites
120. In one embodiment, the number of beeps or blinks corresponds
to the number of satellites 120 in view. For example, one satellite
causes one beep and/or one blink, two satellites cause two beeps
and/or two blinks. After the progress indication at step 53, method
130 continues to step 54. Referring again to step 57, if the predetermined
amount of time has expired, method 130 proceeds to step 59 where
an indication that a location has not been determined is transmitted
to the user. For example, the phrase "LOCATION UNAVAILABLE"
may be enunciated using speaker 11. Method 130 then continues to
step 60 where GPS receiver 22 and processor 23 cease to search for
satellites 120. Method 130 then proceeds to step 48.
Referring again to step 54, if the location coordinates have been
acquired, the coordinates are stored in memories 41 and 27 at step
56. In one embodiment, other associated data, such as time, velocity
and altitude, may also be stored in memories 41 and 27 at step 56.
Method 130 then continues to step 58 where the coordinates and other
data are formatted and encoded into a particular signal format using
output module 100. For example, the determined location coordinates
and optional data are formatted and encoded as DTMF tones. Details
concerning the message format of DTMF tones is described in greater
detail below in conjunction with FIG. 8. Method 130 then continues
to step 62 (shown in FIG. 7B) where a signal indicating that the
user should position mobile phone 3 within an effective range of
output signal 4 is transmitted to the user. For example, the word
"READY" may be enunciated using speaker 11. In one embodiment
where the effective range of output signal 4 is great enough to
eliminate any interaction by the user, step 62 may be omitted. For
example, where wireless Bluetooth.TM. signal has an effective range
covers the cabin of a vehicle, or where phone 3 is coupled to a
particular area of the vehicle that falls within the effective range
of the wireless Bluetooth.TM. signal, the user is not required to
manually position mobile phone 3 in a particular place. Thus, an
indication to place mobile phone 3 within the effective range of
output signal 4 is not necessary, in some embodiments.
Referring to FIG. 7B, method 130 then proceeds to step 63 where
output signal 4 is transmitted. In one embodiment, output signal
4 is transmitted multiple times by output module 100. In one embodiment,
method 130 then continues to step 64 where a test is performed for
the availability of external power 32. If no external power is available,
method 130 continues to step 65 where GPS receiver 22 and processor
23 are powered down to conserve battery. Then method 130 returns
to step 48 shown in FIG. 7A. However, at step 64, if it is determined
that external power is available, method 130 continues to step 66
to determine whether an activation event has occurred. If no activation
event has occurred, method 130 continues to step 67 where processor
23 checks for new location coordinates. If there are no new coordinates,
method 130 loops back to step 64. If location coordinates are available
at step 67, then at step 68 the location coordinates and other data
are stored in memories 27 and 41. Then method 130 proceeds to step
64.
Referring again to step 66, if an activation event has occurred,
method 130 continues to step 69 where memory 41 is tested for valid
location coordinate data. If the location coordinates have not been
updated for a predetermined amount of time (5 seconds, for example)
or non-existent, method 130 proceeds to step 70 where the user is
informed that a location is not determined. For example, the phrase
"LOCATION UNAVAILABLE" may be enunciated using speaker
11. Method 130 then continues to step 64 where the test for external
power is performed.
Returning again to step 69, if coordinates are available, method
130 proceeds to step 61 where the location coordinates and other
appropriate data are formatted and encoded to a particular signal
format, such as DMTF. Method 130 then proceeds to step 62, which
has already been described above.
FIGS. 7C and 7D are flow charts illustrating one embodiment of
a method 200 for power management and location information update
that may be used in conjunction with method 130 of FIG. 7A. For
example, method 200 may be used at steps 60 and/or 65 of method
130. At step 204, processor 23 determines whether information identifying
a location is stored in memories 27 and/or 41. An example of such
information is a GPS grid coordinate identifying the location of
position locator 1. If location information is determined to be
stored in memories 27 and/or 41, then processor 23 sets timer 26
for a predetermined time period (60 minutes, for example). Then
at step 210, processor 23 assumes a sleep mode.
Referring back to step 204, if information identifying a location
is not stored in memories 27 and/or 41, then at step 212, processor
23 determines whether the level of available power from power source
20 is above a predetermined level. For example, the predetermined
level of power may be 80%; however, other predetermined level of
power may be used depending on the design specification of position
locator 1. If the level of available power is determined to be above
the predetermined level, then the "yes" branch is followed
to step 214, where timer 26 is set for a predetermined time period
(15 minutes, for example).
Referring back to step 212, if the power level is determined to
be equal or below the predetermined level, then the "no"
branch is followed to step 218 where timer 26 is set for a time
period that is different than the time period used at steps 208
and 214. For example, timer 26 may be set at 30 minutes. In one
embodiment, the time period of step 208 is longer than the respective
time periods of steps 214 and 218. In one embodiment, the time period
of step 214 is shorter than the respective time periods of steps
208 and 218. Then method 200 proceeds to step 210, which has already
been described above. At step 220, processor 23 determines whether
a particular time period of steps 208, 214, or 218 has expired.
If it has not, then method 200 loops back to step 220. If the particular
time period has expired, then method 200 moves to step 224 shown
in FIG. 7D.
Referring to FIG. 7D, at step 224, processor 23 determines whether
the power level of power source 20 is below a predetermined level.
For example, the predetermined power level may be 80% of the full
capacity of power source 20. If the available power level is below
the predetermined level, then at 228, timer 26 is set for a predetermined
time period. Then at step 244, position locator 1 assumes a sleep
mode.
Referring back to step 224, if the available power level is not
below the predetermined level, then at step 230, timer 26 is set
for another predetermined time period. For example, timer 26 may
be set for 30 seconds at step 230; however, timer 26 may be set
for a different duration. Then at step 234, GPS receiver 22 is activated.
At step 238, processor 23 determines whether the time period of
timer 26 has expired. If not, then method 200 is looped back to
step 238. If the time period is expired, then the "yes"
branch is followed to step 240. At step 240, processor 23 determines
whether there was a prior time period extension. Time period extension
is described below in conjunction with steps 248, 250, 258, and
264. If there was a previous extension of time, then GPS receiver
22 and processor 23 power down and assume a sleep state at step
244. If no previous extension of time was made, then the "no"
branch is followed to step 248.
At step 248, processor 23 determines the number of satellite vehicles
120 from which position locator 1 is able to receive location information.
If the number is 1, then the "1" branch is followed to
step 250 where the time period set at timer 26 is extended by a
first predetermined time period. Then method 200 proceeds to step
238. If the number is 2, then the "2" branch is followed
to step 258 where the time period set at timer 26 is extended by
a second predetermined time period. Then method 200 proceeds to
step 238. If the number is equal to or greater than 3, then the
"3" branch is followed to step 264 where the time period
set at timer 26 is extended by a third time period. Then method
200 proceeds to step 238. If the number is 0, then method 200 moves
to step 244. In some embodiments, method 200 may transition from
step 244 to step 48 of method 130. In some embodiments, method 200
may transition from step 244 to step 50 of method 130.
FIG. 7E is a flow chart illustrating one embodiment of a method
300 for using position locator 1 as an emergency alert device. Method
300 may be used in conjunction with methods 130 and 200. In some
embodiments, method 300 may be implemented prior to step 48 of method
130. For example, after step 47 of method 130, whether an impact
has occurred is determined at step 304. This determination may be
made using impact sensor 19, for example. If no impact has occurred,
then the "no" branch is followed to step 48 of method
130. If an impact has occurred, then position locator 1 is powered
up at step 308. At step 310, processor 23 determines whether a location
of position locator 1 has been determined. If no location information
has been determined, method 300 continues to step 314 where the
elapsed time since the power up at step 50 is determined. If GPS
receiver 22 and processor 23 have been on for less than a predetermined
time period (3 minutes, for example), method 300 continues to step
318 where processor 23 initiates a transmission of a signal indicating
the progress of the satellite search. For example, short audible
beeps and/or blinks from visual indicator 10 may indicate to the
user that locator 1 is in the process of searching for satellites
120. In one embodiment, the number of beeps or blinks corresponds
to the number of satellites in view. For example, one satellite
causes one beep and/or one blink, two satellites cause two beeps
and/or two blinks in rapid succession. After the progress indication
in step 318, method 300 continues to step 310 where the determination
of location is tested.
Referring again to step 310, if location coordinates have been
acquired, then at step 320, the location coordinates and any other
data, such as time, velocity and altitude, are stored in memories
41 and 27. Method 300 then continues to step 324 where the coordinates
and any other data are formatted and encoded into a particular signal
format. For example, the determined coordinates and any other data
are formatted and encoded as Bluetooth.TM. infrared beams. At step
328, position locator 1 transmits a wireless command for mobile
phone 3 to establish a communication channel with a predetermined
location, such as PSAP 6 or other emergency agencies. At step 330,
the location coordinates are transmitted from position locator 1
to mobile phone 3 so that the location coordinates may be routed
to the destination with which mobile phone 3 has established a communication
channel at step 328. Method 300 stops at step 334.
FIGS. 8A and 8B are schematic diagrams illustrating one embodiment
of a message 400 and a message stream 450 that may be transmitted
from position locator 1 to mobile phone 3 as output signal 4. FIGS.
8A and 8B are described jointly. As shown in FIG. 8A, message 400
illustrates an exemplary DTMF signal format comprising location
coordinates and velocity data. Although DTMF encoding is used in
this example, other signal formats may also be used. In some embodiments
where DTMF signal format is used, a DTMF decoder (not explicitly
shown) is located at the destination that is receiving the communication
from mobile phone 1. For example, PSAP 6 or operator station 7 may
have a DTMF decoder that is controlled by a computer or a sound
card within a computer. The DTMF decoder is programmed to detect
the specific tones and also decipher the message contents. However,
other types of decoders may be used where the signal format is different
from the DTMF format.
In one embodiment, a message 400 transmitted from speaker 11 comprises
a latitude group 392, a longitude group 394, and a velocity group
398. Latitude group 392 comprises a delimiter 71, a latitude packet
72, and a checksum 73. Longitude group 394 comprises a delimiter
74, a longitude packet 75, and a checksum 76. Velocity group 398
comprises a delimiter 77, a velocity packet 78, and a checksum 79.
Because delimiters 71, 74 and 77 and checksums 73, 76 and 79 are
used for data integrity and because the data is static during the
output of multiple messages 400, the three message components--latitude
packet 72, longitude packet 75 and velocity packet 78--do not have
to be read in sequence. Delimiters 71, 74, and 77 and checksums
73, 76, and 79 are commonly used techniques for ensuring valid data
and well known to one skilled in the art. In one embodiment, the
use of delimiters 71, 74, and 77 and checksums 73, 76, and 79 is
advantageous because errors in transmitting output signal 4 to mobile
phone 3 may be allowed to occur without causing transmission failure.
This is described below using capture scenarios 80, 81 and 82, in
conjunction with FIG. 8B.
Delimiters 71, 74, and 77 may be thought of as synchronization
characters or boundary markers that indicate the start of a new
message. There are 16 standard DTMF tone pairs in the telephony
standard: 0-9, A-D, * and #. In one embodiment, the tone pairs for
A-D (not found on a typical telephone) are used for delimiters for
latitude group 392 and longitude group 394. In one embodiment, delimiters
71, 74, and 77 may also designate North/South hemispheres and East/West
hemispheres. For example, DTMF values "A" or "B"
may indicate the start of latitude group 392, but "A"
may also indicate the Northern hemisphere whereas "B"
indicates the Southern hemisphere. Likewise, DTMF values "C"
or "D" may indicate the start of longitude group 394,
but "C" also designates the Eastern hemisphere whereas
"D" indicates the Western hemisphere. In one embodiment,
the DTMF value "*" is used as the velocity delimiter digit.
Other DTMF tone pairs may be designated to indicate other information,
as determined by one skilled in the art.
In one embodiment, checksums 73, 76 and 79 are the least significant
base-10 digits derived from the summation of all preceding digit
values for their respective data fields and include their respective
delimiters 71, 74, and 77. For example, checksum 73 of latitude
group 392 is the least significant digit of the sum of delimiter
71 plus all 7 latitude digits in latitude packet 72. At PSAP 6 or
operator station 7, the decoder duplicates this calculation when
receiving the data and compares the transmitted checksum 73 with
the checksum it calculated based upon the received digits. If they
match, then data is considered valid. If they don't match, then
the data is considered invalid.
As shown in FIG. 8B, one embodiment of the format of message 400
may be expressed as
hddmm.mmmshdddmm.mmms*vvvs
where;
h latitude and longitude delimiters and hemisphere designation
(A=Northern Latitude, B=Southern Latitude) (C=Eastern longitude,
D=Western longitude)
d=geodetic degrees
m=geodetic minutes
s=decimal checksum (0-9) for all proceeding digits including the
delimiter
*=velocity delimiter
v=velocity value in miles or kilometers per hour (0-999)
The decimal places are inferred by the receiver but not actually
sent.
In one embodiment, the resolution of the coordinates in the disclosed
format is one thousandth of a minute, which is approximately 6 feet.
Due to digital indecision of one digit, this translates into a tolerance
(error) of +/-6 feet, or less than the length of a sub-compact car.
Referring to FIG. 8B, message stream 450 is formed from multiple
messages 400A, 400B, and 400C that are serially arranged. Each one
of messages 400A through 400C comprises a latitude group 410, a
longitude group 414, and a velocity group 418. In one embodiment,
latitude group 410, longitude group 414, and velocity group 418
are analogous to the respective formats of latitude group 392, longitude
group 394, and velocity group 398. Capture 80 depicts an ideal case
where message 400A is successfully captured without interruption
in the normal sequence. Capture 81 illustrates a case where mobile
phone 3 or the tone decoder has received sufficient signal strength
somewhere in the middle of velocity group 418 of message 400B, causing
that velocity group 418 to fail and be rejected. In this scenario,
however, mobile phone 3 is held in place long enough for the entire
message 400C to be captured successfully. Capture 82 illustrates
a scenario where there is a significant noise level causing some
of the data to be dropped during the transmission of messages 400A
through 400C. In this example, groups from three different messages
400A through 400C have been captured; velocity group 418 from message
400A, longitude group 414 from message 400B, and latitude group
410 from message 400C. The data transfer is complete and valid in
this scenario even though groups 410, 414, and 418 are out of sequence
and from different messages 400A through 400C.
Although some embodiments of the present invention have been described
in detail, it should be understood that various changes, substitutions,
and alterations can be made hereto without departing from the spirit
and scope of the invention as defined by the appended claims. |