Communications: electrical – Vehicle position indication
Utility Patent
1994-12-16
2001-01-02
Swarthout, Brent A. (Department: 2736)
Communications: electrical
Vehicle position indication
C342S457000, C701S300000
Utility Patent
active
06169497
ABSTRACT:
BACKGROUND OF THE INVENTION
A. Field of the Invention
The present invention relates generally to the field of systems for tracking and positioning an entity or target, such as a vehicle or person, by surveillance or tracking persons or stations. More particularly, this invention relates to a mobile tracking and positioning system in which a mobile target is tracked by two or more mobile tracking and positioning stations continuously as all the elements of the system (i.e., the target and the tracking and positioning stations) move about or over the surface of the earth. Some typical applications of the invention are in the private security and transportation industries, where the location of a person or vehicle (or persons and fleets of vehicles) are monitored; the recovery of stolen vehicles; and in government applications such as surveillance, intelligence or counterterrorism, where a person or vehicle is positioned and tracked by police or military units.
B. Description of Related Art
Prior art tracking and positioning systems fall into three general categories: homing systems with one or several homing vehicles, triangulation systems using two fixed points to locate the target, and triangulation systems using one or more fixed points together with a homing vehicle. Each has its own limitations and drawbacks.
Homing systems with mobile vehicles typically use arrows in the vehicle cockpit with a direction finding apparatus. Some detector of proximity to the target is also involved. These systems have no real precision location or mapping capabilities. The present invention provides real-time precision mapping and locating of the target by mobile tracking stations.
Stationary triangulation systems are inherently inflexible, as the position of the triangulation stations is fixed. Ideally, the tracking units should have the flexibility to move about in the surveillance and tracking effort. The present invention provides this capability.
Triangulation systems using a fixed point and a mobile homing vehicle are always obliged to use one fixed antenna. The precision in locating the target is not as good, as the homing vehicle does not know its correct position. Since the calculation of the target location is made at the fixed antenna site, the use of direction finding equipment linked to proximity detectors is necessary at the homing vehicle.
U.S. Pat. No. 5,345,245 to Ishikawa et al. describes a differential ranging system in which a fixed reference with a known position transmits a corrective factor to a mobile station. The system depends upon a fixed station, hence lacks flexibility and true mobility of all parts of the system. Similarly, U.S. Pat. No. 5,111,209 to Toriyama relates to a satellite-based position determination system that is dependent upon fixed stations. The present invention overcomes these drawbacks by providing true mobile tracking capabilities, without the dependency on a fixed antenna or proximity detectors to locate the target, and wherein each of the mobile tracking stations can precisely locate and map the position of the target. As used herein, the term “mobile”, when referring to a tracking and positioning station, refers to a station that has the ability to physically move from one place to another, whether the communication and positioning equipment that constitutes a “station” is installed in a car, an aircraft, a boat, or even carried by a person.
SUMMARY OF THE INVENTION
In one principal aspect of the invention, a mobile tracking and positioning system is provided which comprises a mobile receive station, a mobile transmit and receive station, and a mobile target to be tracked and located by the mobile receive station and the mobile transmit and receive station. The mobile target includes a means for selectively broadcasting a communication signal in response to a tracking and positioning initiation event. In the case where the target is a vehicle, the initiation event could be the unauthorized movement (e.g., theft) of the vehicle, the manual operation of a switch or button, such as an ON-OFF switch associated with the transmission unit of the target, or the transmission of an activation or initiation signal from a portable remote control unit to the target to initiate broadcasting of the communication signal. An example of the communication signal broadcast by the target is a radio signal having a certain frequency or pattern.
The mobile transmit and receive station has a positioning means for substantially continuously determining the position of the mobile transmit and receive station, for example, a global positioning system (GPS) receiver, or a receiver operating under GLONASS (Global Orbiting Navigation Satellite System). The station further includes a direction means for receiving the communication signal broadcast from the target and for responsively determining the direction from the mobile transmit and receive station to the target. Where the communication signal is a radio signal, an example of the direction means would be a radio direction finder (RDF). The station further includes a communications system for transmitting information of the station's position and the direction to the target to the mobile receive station.
The mobile receive station also has a positioning means for determining the position of the mobile receive station (such as, for example, a GPS receiver), a direction means for receiving the communication signal broadcast from the target and for responsively determining the direction from the mobile receive station to the mobile target (such as an RDF), and a communications system for receiving the transmitted information of the position of the mobile transmit and receive station and the direction of the target to the mobile transmit and receive station. The mobile receive station further includes a computer that triangulates the position of the target from the known position of the mobile transmit and receive station, the known position of the mobile receive station, the known direction of the mobile transmit and receive station to the target, and the known direction of the mobile receive station to the target. By virtue of substantially continuous passing of position and direction information from the mobile transmit and receive station to the mobile receive station, and the simultaneous determination of position and direction information at the mobile receive station, the computer can substantially continuously update the position of the target as the target, the mobile transmit and receive station, and the mobile receive station all move about or above the surface of the earth.
The mobile receive station may be provided with the capability of also transmitting its position and direction information to the mobile transmit and receive station, and the mobile transmit and receive station may be provided with a computer to process the position and direction information of both stations to determine the location of the target. This aspect of the invention results in both stations having equal capability to track and locate the target.
In another aspect of the invention, the tracking and positioning system consists of a plurality of mobile transmit and receive stations, each with the capability of (1) transmitting its position and direction information to the other stations, (2) receiving transmissions of position and direction information from the other stations, and (3) processing via a computer the received position and direction information and the station's own position and direction information to determine the location of the target.
In yet another aspect of the invention, the activation of the target to begin transmission of the communication signal may involve the transmission of identification codes to the target. The identification codes are associated with the particular mobile transmit and receive stations that are to participate in the tracking and positioning effort, and with the particular target to be tracked. This option may be utilized where a large number of targets, only one of which is t
McIntyre Hazrbin & King
Robert Bruno G.
Swarthout Brent A.
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