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Claims  |
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I claim:
1. Apparatus for determining the present location of a missing vehicle, the
apparatus comprising:
a GPS signal antenna and receiver/processor, connected to the antenna,
attached to a vehicle, to receive and process GPS signals to determine the
present location of the vehicle to which the antenna and
receiver/processor are attached;
an event sensor that determines when a selected trigger event involving the
vehicle has occurred and issuing a sensor output signal when that event
occurs;
controller means, connected to the GPS receiver/processor and to the event
sensor, for receiving the event sensor output signal and, in response
thereto, for issuing a first output signal that is received by the GPS
receiver/processor that commands the receiver/processor to determine and
issue as an output signal the present location of the receiver/processor,
and for receiving the receiver/processor output signal representing
present location of the receiver/processor and issuing this present
location information as a second output signal;
a cellular telephone, connected to the controller means, for receiving the
controller means second output signal and, in response thereto, for
transmitting the controller means second output signal to a selected
telephone number; and
a power supply to deliver electrical power to at least one of the
receiver/processor, the event sensor, the controller means and the
cellular transmitter,
where the receiver/processor, the event sensor, the controller means, and
the cellular telephone are all carried on the vehicle whose present
location is to be determined.
2. The apparatus of claim 1, wherein the presence of at least one of said
antenna, said receiver/processor and said cellular telephone is concealed
on said vehicle.
3. A method for determining the present location of a missing vehicle, the
method comprising the steps of:
providing a vehicle with a vehicle location signal receiver/processor that
receives position location signals from two or more location-sensing
sensors located on the vehicle and uses these signals to determine the
present location of the vehicle on which the antenna and the
receiver/processor are located, where the receiver/processor comprises:
a plurality of gyroscopes and associated vehicle angular orientation
sensors attached to the vehicle to determine and issue output signals
indicating the present angular orientation of the vehicle;
a vehicle velocity sensor to determine and issue an output signal
indicating the present velocity of the vehicle; and
a signal processor that receives the output signals from the vehicle
angular orientation sensors and the vehicle velocity sensor and determines
the present location of the vehicle from these signals;
providing the vehicle with a page responder to respond to a page request
broadcast by a vehicle location service or paging service;
providing the vehicle with a cellular telephone that may be activated to
place a telephone call to a selected telephone number;
providing the vehicle with a controller/modem that is electrically
connected to, and controls the operation of, the receiver/processor, the
page responder and the cellular telephone;
when the vehicle is determined to be missing, causing the vehicle location
service or paging service to broadcast a page requesting the present
location of the missing vehicle;
causing the page responder in the vehicle to receive the page request and,
in response thereto, to cause the controller/modem to interrogate the
receiver/processor concerning the present location of the vehicle;
causing the receiver/processor to obtain information on the present
location of the missing vehicle and to provide this information for the
controller/modem; and
causing the controller/modem to cause the cellular telephone to contact a
selected vehicle location service or paging service and to communicate
information on the vehicle present location to the vehicle location
service or paging service,
whereby information on the present location of the vehicle is made
available to an owner or operator of the missing vehicle.
4. A method for determining the present location of a missing vehicle, the
method comprising the steps of:
providing a vehicle with a vehicle location signal receiver/processor that
receives position location signals from two or more location-sensing
sensors located on the vehicle and uses these signals to determine the
present location of the vehicle on which the antenna and the
receiver/processor are located, where the receiver/processor comprises:
a plurality of local magnetic field angular orientation sensors attached to
the vehicle to determine and issue output signals indicating the present
angular orientation of the vehicle;
a vehicle velocity sensor to determine and issue an output signal
indicating the present velocity of the vehicle; and
a signal processor that receives the output signals from the vehicle
angular orientation sensors and the vehicle velocity sensor and determines
the present location of the vehicle from these signals;
providing the vehicle with a page responder to respond to a page request
broadcast by a vehicle location service or paging service;
providing the vehicle with a cellular telephone that may be activated to
place a telephone call to a selected telephone number;
providing the vehicle with a controller/modem that is electrically
connected to, and controls the operation of, the receiver/processor, the
page responder and the cellular telephone;
when the vehicle is determined to be missing, causing the vehicle location
service or paging service to broadcast a page requesting the present
location of the missing vehicle;
causing the page responder in the vehicle to receive the page request and,
in response thereto, to cause the controller/modem to interrogate the
receiver/processor concerning the present location of the vehicle;
causing the receiver/processor to obtain information on the present
location of the missing vehicle and to provide this information for the
controller/modem; and
causing the controller/modem to cause the cellular telephone to contact a
selected vehicle location service or paging service and to communicate
information on the vehicle present location to the vehicle location
service or paging service,
whereby information on the present location of the vehicle is made
available to an owner or operator of the missing vehicle.
5. A method for determining the present location of a missing vehicle, the
method comprising the steps of:
providing a vehicle with a vehicle location signal receiver/processor that
receives position location signals from two or more location-sensing
sensors located on the vehicle and uses these signals to determine the
present location of the vehicle on which the antenna and the
receiver/processor are located, where the receiver-processor comprises:
a plurality of gyroscopes and associated vehicle angular orientation
sensors attached to the vehicle to determine and issue output signals
indicating the present angular orientation of the vehicle;
a vehicle velocity sensor to determine and issue an output signal
indicating the present velocity of the vehicle; and
a signal processor that receives the output signals from the vehicle
angular orientation sensors and the vehicle velocity sensor and determines
the present location of the vehicle from these signals;
providing the vehicle with an event sensor to sense occurrence of a
selected vehicle trigger event involving the vehicle;
providing the vehicle with a cellular telephone that may be activated to
place a telephone call to a selected telephone number;
providing the vehicle with a controller/modem that is electrically
connected to, and controls the operation of, the receiver/processor, the
event sensor and the cellular telephone;
when the sensor determines that a vehicle trigger event has occurred,
causing the controller/modem to interrogate the receiver/processor
concerning the present location of the vehicle;
causing the receiver/processor to obtain information on the present
location of the vehicle and to provide this information for the
controller/modem; and
causing the controller/modem to cause the cellular telephone to contact a
selected vehicle location service or paging service and to communicate
information on the vehicle present location to the vehicle location
service or paging service,
whereby information on the present location of the vehicle is made
available to an owner or operator of the vehicle.
6. A method for determining the present location of a missing vehicle, the
method comprising the steps of:
providing a vehicle with a vehicle location signal receiver/processor that
receives position location signals from two or more location-sensing
sensors located on the vehicle and uses these signals to determine the
present location of the vehicle on which the antenna and the
receiver/processor are located, where the receiver-processor comprises:
a plurality of local magnetic field angular orientation sensors attached to
the vehicle to determine and issue output signals indicating the present
angular orientation of the vehicle;
a vehicle velocity sensor to determine and issue an output signal
indicating the present velocity of the vehicle; and
a signal processor that receives the output signals from the vehicle
angular orientation sensors and the vehicle velocity sensor and determines
the present location of the vehicle from these signals;
providing the vehicle with an event sensor to sense occurrence of a
selected vehicle trigger event involving the vehicle;
providing the vehicle with a cellular telephone that may be activated to
place a telephone call to a selected telephone number;
providing the vehicle with a controller/modem that is electrically
connected to, and controls the operation of, the receiver/processor, the
event sensor and the cellular telephone;
when the sensor determines that a vehicle trigger event has occurred,
causing the controller/modem to interrogate the receiver/processor
concerning the present location of the vehicle;
causing the receiver/processor to obtain information on the present
location of the vehicle and to provide this information for the
controller/modem; and
causing the controller/modem to cause the cellular telephone to contact a
selected vehicle location service or paging service and to communicate
information on the vehicle present location to the vehicle location
service or paging service,
whereby information on the present location of the vehicle is made
available to an owner or operator of the vehicle.
7. A method for determining the present location of a missing vehicle, the
method comprising the steps of:
providing a vehicle with a LORAN signal antenna and receiver/processor,
connected to the antenna, where the antenna and receiver/processor receive
time-coded LORAN signals from a plurality of LORAN signal transmitters and
determine the location of a selected vehicle vehicle location from these
signals;
providing the vehicle with a page responder to respond to a page request
broadcast by a vehicle location service or paging service;
providing the vehicle with a cellular telephone that may be activated to
place a telephone call to a selected telephone number;
providing the vehicle with a controller/modem that is electrically
connected to, and controls the operation of, the receiver/processor, the
page responder and the cellular telephone;
when the vehicle is determined to be missing, causing the vehicle location
service or paging service to broadcast a page requesting the present
location of the missing vehicle;
causing the page responder in the vehicle to receive the page request and,
in response thereto, to cause the controller/modem to interrogate the
receiver/processor concerning the present location of the vehicle;
causing the LORAN signal receiver/processor to obtain information on the
present location of the vehicle and to provide this information for the
controller/modem; and
causing the controller/modem to cause the cellular telephone to contact a
selected vehicle location service or paging service and to communicate
information on the vehicle present location to the vehicle location
service or paging service,
whereby information on the present location of the vehicle is made
available to an owner or operator of the missing vehicle.
8. The method of claim 7, further comprising the step of concealing the
presence of at least one of said antenna, said receiver/processor and said
cellular telephone on said vehicle.
9. The method of claim 7, further comprising the step of decoding said
vehicle present location information received by said vehicle location
service or paging service.
10. The method of claim 7, further comprising the step of causing said
cellular telephone to communicate said present location information for
said vehicle at least twice in response to receipt of said page request by
said controller/modem.
11. The method of claim 7, further comprising the step of causing said
cellular telephone to communicate said present location information for
said vehicle once in response to receipt of said page request by said
controller/modem.
12. The method of claim 7, further comprising the step of displaying said
present location of said vehicle on a map or visual display after said
present location information is received by said vehicle location service
or paging service.
13. The method of claim 7, further comprising the step of causing said
receiver/processor to occupy an inactive mode and to reduce its electrical
power consumption, except when responding to receipt of said interrogation
from said controller/modem.
14. The method of claim 13, further comprising the step of periodically
activating said receiver/processor for a selected time interval and
causing said receiver/processor to redetermine its present location.
15. The method of claim 7, further comprising the step of concealing the
presence of at least one of said receiver/processor, said antenna and said
cellular telephone on said vehicle.
16. The method of claim 7, further comprising the step of choosing said
vehicle location signal antenna and receiver/processor to be a GPS signal
antenna and receiver/processor that receive time-coded GPS signals from
one or more satellites and determine said vehicle location from these
signals.
17. A method for determining the present location of a vehicle that has
been moved or tampered with in an unauthorized manner, the method
comprising the steps of:
providing a vehicle with a vehicle location signal antenna and
receiver/processor, connected to the antenna, where the vehicle location
signal antenna and receiver/processor are drawn from the class consisting
of (i) a GPS signal antenna and receiver/processor that receive time-coded
GPS signals from one or more satellites and determine the present location
of a selected vehicle from these signals and (ii) a LORAN signal antenna
and receiver/processor that receive time-coded LORAN signals from a
plurality of LORAN signal transmitters and determine the present location
of a selected vehicle from these signals;
providing the vehicle with an event sensor to sense occurrence of a
selected vehicle trigger event involving the vehicle;
providing the vehicle with a cellular telephone that may be activated to
place a telephone call to a selected telephone number;
providing the vehicle with a controller/modem that is electrically
connected to, and controls the operation of, the receiver/processor, the
event sensor and the cellular telephone;
when the sensor determines that a vehicle trigger event has occurred,
causing the controller/modem to interrogate the receiver/processor
concerning the present location of the vehicle;
causing the receiver/processor to obtain information on the present
location of the vehicle and to provide this information for the
controller/modem; and
causing the controller/modem to cause the cellular telephone to contact a
selected vehicle location service or paging service and to communicate
information on the vehicle present location to the vehicle location
service or paging service,
whereby information on the present location of the vehicle is made
available to an owner or operator of the vehicle.
18. The method of claim 17, further comprising the step of concealing the
presence of at least one of said antenna, said receiver/processor and said
cellular telephone on said vehicle.
19. The method of claim 17, further comprising the step of choosing, as
said vehicle trigger event, the unauthorized movement of said vehicle, as
sensed by said event sensor.
20. The method of claim 17, further comprising the steps of:
choosing as said event sensor a vehicle security alarm that senses
occurrence of an unauthorized action affecting said vehicle; and
choosing, as said trigger event, activation of this security alarm.
21. The method of claim 17, further comprising the step of decoding said
vehicle present location information received by said vehicle location
service or paging service.
22. The method of claim 17, further comprising the step of causing said
cellular telephone to communicate said present location information for
said vehicle at least twice in response to occurrence of said vehicle
trigger event.
23. The method of claim 17, further comprising the step of causing said
cellular telephone to communicate said present location information for
said vehicle once in response to occurrence of said vehicle trigger event.
24. The method of claim 17, further comprising the step of displaying said
present location of said vehicle on a map or other visual display after
said present location information is received by said vehicle location
service or paging service.
25. The method of claim 17, further comprising the step of causing said
receiver/processor to occupy an inactive mode and to reduce its electrical
power consumption, except when responding to receipt of said interrogation
from said controller/modem.
26. The method of claim 25, further comprising the step of periodically
activating said receiver/processor for a selected time interval and
causing said receiver/processor to redetermine its present location.
27. The method of claim 17, further comprising the step of concealing the
presence of at least one of said antenna, said receiver/processor and said
cellular telephone on said vehicle. |
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Claims |
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Description |
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FIELD OF THE INVENTION
This invention relates to use of a Global Positioning System or other
location system for location of missing vehicles and to communication on
demand of vehicle location information by a missing vehicle.
BACKGROUND OF THE INVENTION
Movable vehicles, such as automobiles, trucks, buses, boats, airplanes,
motorcycles and motorized bicycles, are occasionally misplaced, lost or
stolen, sometimes permanently. Between one and two percent of the
automobiles three years old or less are stolen or taken, and the
percentage of recovery of such vehicles is about 63 percent. Several
inventors have developed methods that might be used to recover a missing
vehicle, by continuous tracking of that vehicle.
A personnel locator system is disclosed in U.S. Pat. No. 3,439,320, issued
to Ward. Each person carries a sensor/transmitter that emits a unique
frequency whenever that person enters any one of a plurality of selected
areas in a facility, with each such area having a receiver that receives
this signal and transmits this information to a central processor. The
processor keeps track of the movements of each person from one selected
area to another area so that, at any given time, the processor can
identify the selected area a given person now occupies. This approach is
limited to a relatively small geographic area and to a relatively small
number of covered persons.
Serrano et al disclose a microprocessor-controlled interface for a cellular
phone system to be carried in a vehicle, in U.S. Pat. No. 4,718,080. A
telephone handset communicates with the cellular transceiver along a bus
and through the microprocessor that interprets bus logic signals,
including voice and data signals. No integration is disclosed of the
on-board cellular system with any instrument that reports vehicle
operating information upon command received from a remote site.
U.S. Pat. No. 4,797,671, issued to Toal et al, discloses a motor vehicle
locator system that indicates the location of a parked vehicle within a
controlled area, such as a large parking lot. Each parked vehicle carries
a receiver and audio/visual signal emitter. The receiver responds only to
receipt of a signal having a unique frequency and causes the emitter to
emit an audible or visually perceptible signal that indicates the present
location of the parked vehicle. This approach requires that the vehicle be
located within a controlled area of modest size, probably no larger than a
city block.
Ando et al,, in U.S. Pat. No. 4,837,700, disclose method and apparatus for
processing and displaying the present location of a road vehicle, using a
GPS receiver to provide data on vehicle location. This approach provides
continuous information on vehicle location and vehicle orientation or
movement vector based upon sensing the Earth's local geomagnetic field
direction. An angular rate sensor determines, and optionally displays, the
angular rate of change of vehicle orientation, and an odometer determines
the distance the vehicle has moved over some predetermined time interval.
The present vehicle location can be displayed graphically on an electronic
map carried within the vehicle, with a sequence of maps being used to
display the changing vehicle location. Map size can also be increased or
decreased, and the displayed map can be automatically scrolled as vehicle
position changes. A keyboard is available for entering instructions into a
controller or processor. A reference location can be entered into the
system, and vehicle location can be determined relative to this reference
location. The location data can be stored if these data are acceptable and
can be dumped into a bit bucket if these data are not acceptable.
In U.S. Pat. No. 4,924,402, Ando et al disclose a more detailed approach
for determining and graphically displaying vehicle location using a GPS.
This system uses a magnetic field sensor, an angular velocity sensor and a
travel distance sensor together with GPS data and stores maps together
with numerical data that describe useful features of the local terrain.
Sensing of vehicle distance traveled and directional rams made is intended
to be sufficiently accurate that the map displays the location of the
vehicle relative to road intersections (i.e., approaching, passing
through, turning, etc.). With reference to FIGS. 16-17, 22, 27-28 and 30,
the invention appears to put a premium on receiving GPS data that are
accurate to within one meter.
A paging system with paging request receivers that respond or are
controlled differently, depending upon receiver location, is disclosed by
Vrijkorte in U.S. Pat. No. 4,943,803. Using "angle modulation" whose
operation is not explained, the paging request receiver is said to pick
out the strongest transmission control signal from among simultaneously
transmitted control signals and to respond to this signal, if the signal
received includes the receiver's predetermined address code. The receiver
goes into a "sleeper" mode if no signals specifically addressed to that
receiver are received within a selected time interval. The receiver is
activated for receiving a control message by receipt of a receiver
activation signal that may vary with the geographic zone presently
occupied by the receiver.
A portable target locator system is disclosed by Ruszkowski in U.S. Pat.
No. 4,949,089. The locator uses a laser beam target locator and a GPS. The
target locator is aimed by an observer on the ground at a nearby target,
such as a moving tank. The position of the target is sensed using a return
signal received by the target locator, and the position coordinates are
transmitted by a modem to a weapon system, such as an aircraft. The weapon
system uses this target position to direct a bomb or whatever to the
target. If GPS position information is unavailable, the target position is
determined manually. The target locator includes a rifle-like beam
director that determines the target location relative to the beam director
location and orientation. This information is transmitted to the weapon
system, which also senses its own GPS-determined system and determines
target position by an approach that may use differential positioning.
Nishikawa et al disclose a land vehicle navigation system in U.S. Pat. No.
4,949,268. A combination of three or more GPS satellites is selected, from
among all available GPS satellites, that provides the best vehicle
location data. Here, a figure of merit used is minimum position dilution
of precision ("PDOP") associated with the data received from a given group
of GPS satellites. This approach seeks to account for the possibility that
one or more buildings or other structures of relatively great height may
preclude satellite visibility. The height of the structures in that area
may be stored as part of a map in a GPS processor on board the land
vehicle whose location is to be determined. The on-board system seeks
combinations with the highest number of satellites visible, then works
from these combinations to minimize the PDOP or a similar figure of merit
for GPS position data.
Bezin et al disclose a system for managing already-paid vehicle parking
fares by means of information cards affixed to the vehicles, in U.S. Pat.
No. 4,982,070. The card contains a confidential identification number for
the vehicle and the prepaid vehicle parking and includes an adhesive label
that allows the card to be affixed to a vehicle windshield or another
visible area. A portable card checking machine, carded by a roving parking
lot operator, allows readout of this information from the card.
A satellite signal tracking method for signal reacquisition in the presence
of a "dead zone", such as a tunnel or very tall adjacent building that
interrupts receipt of all GPS signals, is disclosed by Ando in U.S. Pat.
No. 4,983,980. The tracking system determines the satellite that had the
maximum elevation angle at the moment the GPS signals are interrupted and
seeks and m-tracks that satellite as soon as the receiver clears the dead
zone. The signal from the satellite with the next highest elevation angle
is then reacquired and re-tracked, and so on. This allegedly minimizes the
time for signal reacquisition. Little quantitative information is
disclosed in this patent.
Scribner et al disclose a vehicle tracking system that records, but does
not transmit, the location of a vehicle whenever one or more predetermined
events occurs in U.S. Pat. No. 5,014,206. The vehicle carries sensors that
respond to occurrence of a predetermined event and carries a GPS or LORAN
navigational system that receives vehicle location information, such as
longitude and latitude. This vehicle location information is stored in a
memory on board the vehicle only when one or more of the predetermined
events occurs. The vehicle location information is assumed to be read out
periodically when the vehicle returns to a home base.
In U.S. Pat. No. 5,043,736, Damell et al disclose use of a combined
cellular telephone and GPS portable receiver system that provides latitude
and longitude coordinate information for the receiver. The GPS receiver
has a modem and transmitter connected thereto that transmit its position
to an accessible cellular phone, which in turn notifies a stationary base
unit of the location of the GPS receiver. The base unit graphically
displays the present location of the GPS receiver. This patent does not
disclose communication with the receiver by a paging system located
elsewhere, to activate the transmitter and modem, nor activation of a GPS
receiver in a vehicle that is later determined to be missing.
On-board navigation apparatus, to be carded on a vehicle to compare present
and immediate-past locations as determined from GPS data, is disclosed by
Odagawa et al in U.S. Pat. No. 5,087,919. A map containing coordinates for
all roads in a region of the Earth's surface is stored electronically in a
navigation system on board the vehicle, as part of a "map" of the region.
The navigation system apparently assumes that the vehicle stays on one of
the roads. Using the continuously arriving GPS data, the system searches
for the nearest road segment that is consistent with these data to
determine present location of the vehicle. Only latitude and longitude
data are needed here so that fewer than four satellites may be used to
determine the present location. Elevation data are provided as part of the
road description stored in the navigation system. This system would not
work well for a vehicle, such as an off-road land vehicle or a marine
vessel, that has no fixed system of roads or paths to follow. This
approach would not be particularly useful in determining the location of a
stolen vehicle, unless the thief could be relied upon to stay on the
conventionally describable roads.
Timothy et al, in U.S. Pat. No. 5,101,356, disclose providing a surface or
airborne vehicle with three spaced apart antennas, each connected to a GPS
receiver. The receiver output signals are connected to a phase comparator
system that compares GPS signal phase differences and determines the
vehicle attitude or orientation (pitch, roll and yaw) relative to a fixed
spatial frame. Location of the vehicle is not of interest here.
Lojack Corp. of Dedham, Mass. has demonstrated a vehicle location system
using triangulation of radio signals transmitted from the vehicle by a
large number of receivers that are strategically positioned around a
community. The vehicle transmitter is remotely activated by a signal
broadcast from elsewhere.
These patents disclose use of GPS or related technology for determination
of location or orientation of a person or vehicle continuously or at
discrete times, without regard to the associated consumption of power,
cost of tracking the vehicle, or cost of communicating the vehicle
location. What is needed is a system that allows determination of location
of a vehicle only when a trigger event occurs, such as misplacement or
theft or unauthorized movement of the vehicle, so that power usage is
controllable and is minimized, and communication from and tracking of the
vehicle are minimized. The system should allow communication at will
between the GPS receiver and an inquirer located elsewhere.
SUMMARY OF THE INVENTION
These needs are met by the invention, which provides method and apparatus
for determination of vehicle location, usually when a trigger event
occurs, such as determination that the vehicle is missing or that the
vehicle has been moved without disabling a silent alarm on the vehicle.
When the trigger event occurs, the vehicle owner or operator contacts a
vehicle location service center, which broadcasts a page requesting the
present location of the vehicle. The paging responder responds by
notifying another entity, either electronically or visually or aurally,
that the responder has received a page request focused on that page
responder. The target of the page signal, usually a person or another
electronic communications device, then responds in a predetermined manner.
A battery back-up is optionally provided to provide power for this
apparatus.
The page request from the vehicle location service center is received by a
paging responder installed in the vehicle. A controller/modem, a Global
Positioning System receiver/processor and a cellular telephone are also
installed in the vehicle. The paging responder causes the controller/modem
to interrogate the GPS receiver/processor to determine the present
location of the vehicle. The receiver/processor determines the present
vehicle location, from signals received by the receiver/processor from one
or more GPS satellites, and communicates the present vehicle location
information to the controller/modem. The controller/modem causes the
cellular telephone to contact the vehicle location service center and to
transmit to the center the present vehicle location information, for
subsequent recovery of the vehicle or a related purpose. The page request
may be coded to solicit one or more of several predetermined responses by
the vehicle, such as contacting different telephone numbers. The GPS
receiver/processor can be replaced by a receiver/processor that works with
a LORAN system, or with a group of gyroscopes or local magnetic field
sensors mounted on the vehicle.
The method and apparatus of the invention provide a missing vehicle locator
system that allows a missing vehicle to be located anywhere on the Earth's
surface that can be reached by a vehicle location paging request and GPS
signals. The portion of the apparatus contained in the vehicle is
preferably hidden and not in plain view of any person within or adjacent
to the vehicle. Communications between the page broadcaster, the vehicle
location center and the missing vehicle do not call attention to
themselves so that no one in or adjacent to the missing vehicle is aware
that such communications are being transmitted.
Because vehicle location is only reported after occurrence of a trigger
event, such as determination that the vehicle is missing, the vehicle
location service center tracks only a relatively small number of vehicles
at one time, namely missing vehicles.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1 is a schematic view of apparatus for practice of the invention.
FIGS. 2 and 3 are flow charts for practice according to two embodiments of
the invention.
FIGS. 4 and 5 are schematic views of apparatus according to the two
embodiments of the invention.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 illustrates apparatus used to locate a missing vehicle according to
the invention. A vehicle owner or operator 11 realizes that his/her
vehicle 13 is missing and initiates a GPS-assisted search for the vehicle
by notifying a vehicle location center 15. The vehicle locator center 15
sends a vehicle pager request to a pager network 17, or initiates a
vehicle pager request itself. A vehicle page is broadcast, specifying the
missing vehicle 13 by means of a unique identifying code address or by
other appropriate vehicle identification means. The vehicle 13 carries a
paging responder 19, a controller/modem and interface 21, a cellular
telephone 23 and associated antenna 24, and a GPS signal
receiver/processor 25 that are electronically connected together.
Preferably, each of these devices is concealed on or within the vehicle
13. For example, the receiver/processor 25 has one or more GPS antennas 27
(also hidden) to receive GPS position signals S1j and S2j(j=A, B, C) at
the two frequencies used by each of the one or more GPS satellites 29A,
29B and 29C that transmit such signals. This antenna (or antennas) 27 can
be mounted on or within one or more bumpers 31 or other projections of the
vehicle 13, on a rear or side window of the vehicle, within a roof or top
panel 33 of the vehicle 13, or elsewhere. Preferably, the antennas 24 and
27 are mounted on the vehicle so that the presence of these antennas is
hard to detect.
A "page ", as used herein, is a radiowave or other electronic
communication, broadcast in a selected frequency band, that is intended
only for and is sensed only by a particular receiver, referred to herein
as a paging responder. A person or electronic device that carries or is
attached to the paging responder then responds by placing a telephone call
or by performing some other task to respond affirmatively to the page.
Operation of a paging system is discussed by Ward in U.S. Pat. No.
3,439,320 and by Bunting in U.S. Pat. No. 3,599,200, both incorporated
herein by reference.
The GPS signal receiver/processor 25 can operate only in response to
receipt of an interrogation signal from the controller/modem 21, if
desired, in order to reduce the electrical current draw from a power
supply for the controller/modem. In this embodiment, the
receiver/processor 25 is normally in a "sleeper" mode and is awakened only
when needed. This approach conserves electrical power used to operate the
receiver/processor 25 and also makes detection of the presence of the
apparatus more difficult. Alternatively, the receiver/processor 25 may be
awakened periodically (e.g., once every 15 minutes) to obtain a new fix on
the GPS satellite(s) that provides the signals needed to calculate the
present vehicle location. This apparatus serves as a missing vehicle
locator system according to the following procedure.
FIG. 2 illustrates, in flow chart form, a procedure that can be followed to
locate a missing vehicle. In step 41, a vehicle owner or operator notices
that his/her vehicle 13 is missing and notifies a vehicle location service
center (the "Center") 15. In step 43, the Center (or the vehicle owner)
sends a page request to a pager network or broadcasts a paging request
itself. A paging request is broadcast, requesting a response indicating
the present location of the missing vehicle 13, in step 45. In step 47,
the page responder 19 in the missing vehicle 13 receives the paging
request and notifies the controller/modem 21 that a vehicle location
request was received. In step 49, the controller/modem 21 interrogates the
GPS signal receiver/processor 25, also located in the vehicle, as to the
present, or last known, vehicle position. In step 51, the
receiver/processor 25 obtains the present location information for the
vehicle 13 from the GPS satellite signals and sends this position fix to
the controller/modem 21. The receiver/processor 25 may have received this
information continuously in the recent past, or the GPS receiver may have
been "awakened" and caused to determine the present vehicle position by a
missing vehicle notification received from the controller/modem 21.
In step 53, the controller/modem 21 causes the cellular telephone or
similar communication means 23, also located in the missing vehicle 13, to
place a call to the Center or to the owner. The handset for the cellular
telephone 23 may be disabled by the controller/modem 21 to make the
cellular phone appear to be non-operational, if the cellular phone is not
hidden from view. When the Center answers the call from the cellular
telephone 23, the controller/modem 21 transmits the vehicle present
location information to the Center in a short burst of data, in step 55.
The vehicle present location information can be updated continuously or
intermittently, or the cellular telephone 23 may respond only once, as
desired. In step 57, the Center decodes the vehicle position information
(if this information is not already decoded), displays the vehicle present
location on a map (optional), and notifies the vehicle owner and/or police
of the vehicle's present location. The vehicle owner and/or police can
then recover the missing vehicle. When the telephone call is terminated by
the Center, the controller/modem discontinues sending location fixes.
Alternatively, the trigger event that causes the vehicle location center 15
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