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CLANDESTINE LOCATION REPORTING BY
A MISSING VEHICLE
FIELD OF THE INVENTION
This application is a continuation-in-part of a patent application entitled "Clandestine Location Reporting For Missing Vehicles," U.S. Ser. No. 08/157,726, now abandoned assigned to the assignee of this application. This invention relates to clandestine use of location determination systems, such as the Global Positioning System, to monitor and report on the location of a missing vehicle.
BACKGROUND OF THE INVENTION
As used herein, the term "vehicle" refers to land vehicles, to marine vehicles or vessels, and to aircraft. In the United States, about 1.7 million automotive vehicles and about 100,000 marine and aircraft vehicles are reported missing (or stolen) each year. The probability that a land or marine vehicle will be recovered drops dramatically after the vehicle or vessel has been missing for 24 hours or more. Thus, time is of the essence in locating and retrieving a missing vehicle.
Sheffer, in U.S. Pat. No. 4,891,650, discloses a vehicle location system that disperses an array of cellular monitoring stations, each of which detects a cellular alarm signal that is transmitted from a vehicle when the vehicle is determined to be missing. Vehicle location is determined at a base station by the relative alarm strength measured at each detector.
U.S. Pat. No. 5,043,736, issued to Darnell et al, discloses a portable vehicle locating system that uses a Global Positioning System (GPS) to determine vehicle location, a cellular phone to report this location to a base station, and an interface to convert GPS signals to cellular phone signals for transmission.
A position-aided subscriber unit for a satellite-based cellular phone system is disclosed by Durboraw in U.S. Pat No. 5,119341. A GPS unit determines the location of a transceiver on the ground and transmits This location information to a satellite, to increase the efficiency of satelliteto-receiver communication. This apparatus has use in asset management and in search-and-rescue operations.
Wortham, in U.S. Pat Nos. 5,155,689 and 5,398,190, discloses installation of a mobile cellular phone unit, with its own identification number, an unspecified location determination unit, and an interface between these two units within a vehicle, to determine and transmit vehicle location. This vehicle location information is displayed on a screen in the vehicle and is periodically transmitted to a base station that is located elsewhere.
An airplane theft detection system that includes a dedicated transponder is disclosed by Robinson et al in U.S. Pat No. 5,159,344. When the aircraft carrying this transponder is stolen, turning on the aircraft engine activates this transponder and deactivates the normal transponder carried by the aircraft. The dedicated transponder then broadcasts a signal to all nearby air controllers that this aircraft has been stolen. This dedicated transponder has its own current leads to a battery and cannot be de-activated by turning off the normal aircraft operations system. A separate, concealed switch allows the dedicated transponder to be deactivated and allows a normal transponder to be activated. This patent discloses no system for determining the present location of the aircraft or for communicating this present location information to a central station.
In U.S. Pat. No. 5,187,805, Bertiger et al disclose a telemetry, tracking and control (TT&C) system for satelliteaided cellular communications. Here, the cells for the cellular phone system move with the satellite used for the link. 5 GPS-determined location of a mobile user station is used to facilitate handoff from one satellite to another as a satellite cell pattern sweeps across a region conlaining one or several users.
Song discloses a vehicle locating and navigating system 10 in U.S. Pat. No. 5,208,756. A small receiver, hidden on the vehicle, is activated by a plurality of DTMF signals transmitted from telephone stations with fixed, known locations. The vehicle receiver determines the present location of the vehicle, using relative or absolute signal strengths of the 15 received signals and triangulation of these signals. The vehicle location information is then transmitted to a base station, using a voice synthesis and/or digital signals.
A vehicle tracking system that uses an array of spaced apart cellular phone receivers is disclosed in U.S. Pat. No.
20 5,218367, issued to Sheffer et al. One or more sensors, such as vehicle break-in sensors, is positioned on a vehicle, and a cellular phone transmitter on the vehicle transmits a cellular signal when a corresponding sensor is activated. The vehicle's location is determined at a base station, using
25 relative signal strengths of these signals, as received at several spaced apart receivers.
U.S. Pat. No. 5,223,844, issued to Mansell, discloses a vehicle tracking and security system that provides vehicle
30 location information where vehicle break-in, theft, breakdown or other unusual events or emergencies occur. Several "mobile units," each including some type of event sensor, are hidden on the vehicle. When a sensor senses occurrence of an alarm condition or event, a mobile unit causes an
35 on-board transmitter to transmit an event alarm or signal to a control center, together with the location of the vehicle as determined by an on-board GPS receiver. The control center then takes appropriate action, depending on the condition or event and the location of the vehicle.
4q Dennison discloses a cellular phone system that uses GPS-determined location of a vehicle in which the phone unit is carried to make call management decisions, such as call handoff, in U.S. Pat. No. 5,235,633. The vehicle location information is transmitted to a call management site that
45 determines when cell handoff will occur for a given mobile cellular phone unit.
A vehicle occupant personal security system using Loranbased or GPS-based location determination is disclosed by Simms et al in U.S. Pat. No. 5334,974. When an emergency
50 condition sensor installed on the vehicle senses the presence of an alarm condition, an on-board system activates a cellular phone system and determines the vehicle location. The on-board system then transmits an emergency condition identifier, a vehicle identifier and vehicle location informa
55 tion to a central station, requesting an appropriate response. What is needed is a system including ceEular telecommunication means that allows determination and reporting of the present location of a missing vehicle, using clandestine means on the vehicle itself. Preferably, the cellular
60 means (1) will function in a normal manner, if used by a vehicle occupant while the vehicle is missing, and (2) can be used to determine and transmit a report on the present location of the missing vehicle, if commanded to do so by a central station that communicates with the vehicle.
65 Preferably, the system should allow recording of any telecommunications made using the cellular means while the vehicle is missing.
SUMMARY OF THE INVENTION
These needs are met by the invention, which provides a location determination and reporting (LDR) system for clandestinely deterrnining and reporting on the present location of a missing vehicle. The vehicle may be in motion or may be motionless when its location is determined and reported, and the vehicle may be anywhere within reach of a cellular station to which the location is reported.
A vehicle is equipped with an operating cellular telephone, with a location determination (LD) unit, including an LD signal antenna and receiver/processor (preferably hidden on the vehicle), that determines the present location of the LD antenna, and with a cellular telephone/LD unit controller and interface. If (or when) the vehicle is reported missing, stolen or moved without authorization from its last known resting place, a central station uses the cellular telephone facility to interrogate the vehicle to determine the present location of the vehicle, even if the vehicle is presently in motion. The owner, agent or other interested person makes a phone call to the cellular phone unit in the vehicle and transmits a location interrogation message that commands the LD signal receiver/processor to provide information on the present location of the LD antenna for transmission by the vehicle cellular phone unit to a designated central station where the owner, tracking agent or police are waiting. When the vehicle cellular phone is contacted and the clandestine vehicle tracking mode is activated, the phone will not signal receipt of an incoming call for an initial time interval of length Atd (At^O.2-30 sec, preferably Atrfl-5 sec), awaiting receipt of an anticipated location interrogation signal from the central station requesting that the cellular phone unit provide present location information for the vehicle. If the cellular phone receives this location interrogation signal within the initial time interval of length Atd, the cellular phone does not "ring" in the usual sense, provides no indication that it is communicating with the designated station, and transmits information on the vehicle's present location to the central station.
However, if the anticipated location interrogation signal is not received within the initial time interval of length Atd, the cellular phone will then "ring" audibly or otherwise signal visually, after a time delay of Atd, and behave as a normal cellular phone for the remainder of that phone call. When the system is in a clandestine tracking mode, the controller and cellular phone in the vehicle answer any incoming phone call with a simulated ringing, to avoid alerting any caller to the unusual nature of this phone system If the incoming call is not a location interrogation signal, the cellular phone handset produces a standard audible ringing tone, and a vehicle occupant can respond to the incoming phone in a normal manner. If the incoming phone call is not answered, the controller and cellular phone will continue to transmit the sounds of simulated ringing or actual ringing for the benefit of the caller, until the caller disconnects, or until a selected large number of rings, such as 10 or 20, has occurred.
The cellular phone may function normally if a person in the vehicle attempts to use the phone. This activity will temporarily pre-empt use of the cellular phone to respond to a location interrogation signal. Thus, an unauthorized user of the vehicle receives no warning or indication that the innocuous cellular phone in the vehicle is being used, or can be used, to track the present location of the vehicle. If one or more phone calls is received by or made from the vehicle while the vehicle is missing, the cellular phone unit and controller can record the telephone number of the calling or
called person and/or the voice communication itself during this period, and can transmit this recorded information upon receipt from the central station of a voice communication interrogation signal. Alternatively, the cellular phone can be 5 disabled and rendered unusable unless affirmative action is taken by the vehicle owner or authorized operator, by toggling a concealed switch or entering a confidential alphanumeric symbol sequence into a microprocessor, using an on-board keypad.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view illustrating use of one embodiment of the invention for determining the location of a land vehicle, using a satellite-based LD system, such as the Global Positioning System
FIG. 2 is a schematic view illustrating use of one embodiment of the invention for determining the location of a land vehicle, using a ground-based LD system, such as an FM 20 subcarrier system or a Loran system.
FIG. 3 is a schematic view illustrating use of another embodiment of the invention for a marine vessel.
FIG. 4 is a schematic view of an embodiment of apparatus that may be installed in a vehicle for determining and 25 reporting on the present location of the vehicle.
FIGS. 5A and 5B are a flow chart illustrating a procedure followed by an LDR unit according to an embodiment of the invention.
30 DESCRIPTION OF BEST MODE OF THE
FIG. 1 illustrates use of the invention to monitor and report on the location of a land vehicle 11, using a satellite
35 based LD system. A cellular telephone unit 13, LD unit 15 and cellular phone/LD unit controller 17 are installed in the vehicle 11. The cellular phone unit 13 is placed in plain sight of, and within the reach of, an operator of the vehicle 11, as a normal cellular phone would be. The cellular phone 13 is
40 connected to a power supply 19 and operates as a normal cellular phone for most purposes. The LD unit 15, preferably hidden from view on the vehicle 11, has an LD signal antenna 23 and associated LD signal receiver/processor 25 that receive LD signals from three or more LD system
45 satellites 27, 29, 31, 33 and determine the present location of the LD antenna, either continuously or periodically or upon demand. The cellular phone unit 13, LD unit 15 and controller 17 (also preferably hidden from view on the vehicle) together form a location determination and report
50 ing (LDR) unit that may be used to practice the invention in one embodiment
The LD unit 15 is connected to the cellular phone unit 13 through the controller unit 17 that (1) receives cellular phone messages through the cellular phone and (2) delays audible
55 or visual signalling of an incoming call to a vehicle occupant by the cellular phone for a period of time Atd, (At^O.2-30 sec, preferably At^l-5 sec) to determine whether the cellular phone message is a normal message or is a location interrogation signal. However, the controller unit 17 and
60 cellular phone unit 15 produce a simulated tinging for the benefit of the caller (only) on an incoming call, to avoid alerting this caller to the primary purpose of the cellular phone. If the incoming call is not a location interrogation signal, after the time-out interval of length Atd the cellular
65 phone handset receives a standard audible ringing tone, and a vehicle occupant can respond to the incoming phone in a normal manner. If the incoming phone call is not answered