Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1999-07-29
2001-11-20
Urban, Edward F. (Department: 2683)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S414200, C342S457000
Reexamination Certificate
active
06321091
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention pertains generally to locating and tracking system. More particularly, the invention is a tracking and locating system and method which provides for a lightweight and portable tracking locator device, which is easily transferable from one user to another user or from first a object to a second object, which provides power saving and conserving features associated with the locator device, and which further provides positional information of such locator devices in the form of hypertext markup language pages viewable on the Internet.
2. The Prior Art
Wireless devices of all kinds have been in use for pinpointing objects, people and animals on the surface of the earth, under water, or in space. Some wireless devices also provide navigational information such as whether or not a moving vessel or vehicle is “on course” to its predetermined destination. Radio frequency (RF) location and navigation systems are the oldest, and more recently developed devices function at infrared (IR) and visible wavelengths. Acoustic location and navigation systems such as sonar also exist.
Traditional radiolocation is the process of determining the position of a vehicle, aircraft, or vessel. Radionavigation is the use of radio apparatus, by personnel aboard moving vessels, for the purpose of plotting and maintaining a course.
The simplest method of radiolocation is known as the “directional method” wherein two or more fixed receiving stations, which are separated by a fixed distance, receive radio transmission signals from a transmitter that is mounted on a vessel. The vessel location is determined from the intersection of great circles drawn outward from the receiver station points in the appropriate directions.
A second implementation for determining the position of objects involves radar. The term “radar” is an acronym derived from the words “radio detection and ranging.” Electromagnetic (EM) waves having certain frequencies reflect from various objects, particularly if those objects contain metals or other electrical conductors. Using a transmitter, receiver, and a display at a fixed station, the location of flying objects with respect to the fixed location may be determined by ascertaining the directions from which radio signal are returned, and by measuring the time it takes for an EM pulse to travel from the transmitter to a target and back. However, such radar systems are not useful for tracking a ground moving objects, or objects which have poor EM reflective properties. Additionally, radar systems are not normally useful for differentiating the identity of objects, particularly when there are a plurality of objects.
The most sophisticated radiolocation and radionavigation techniques employ the global positioning system (GPS). The GPS is a network of radiolocation and radionavigation apparatus that operates on a worldwide basis. The GPS system employs several satellites and allows determination of latitude, longitude, and altitude.
Most recently, vehicle location and navigation systems have been adapted to track the location of automobiles using the GPS system. Such systems include sensors which are fixed to the automobile and draw power from either the car battery or a second large power source. The purpose of fixing the automobile tracking sensor to the vehicle is primarily for security reasons. Because one main purpose of the tracking system to locate the vehicle in cases of theft, it is important that the sensor systems of the tracking systems be mounted or otherwise fixed to the vehicle, making such sensor systems not easily removed or transportable from a first object to a second object. Furthermore, because a large power source such as a car battery is normally available to such tracking systems, intelligent power saving or conserving features are not provided.
Accordingly, there is a need for a tracking and locating system and method which provides for a lightweight and portable tracking locator device, which is easily transferable from user to user or object to object, which provides power saving and conserving features associated with the locator device, and which further provides positional information of such locator devices in the form of hypertext markup language pages viewable on the Internet. The present invention satisfies these needs, as well as others, and generally overcomes the deficiencies found in the background art.
BRIEF DESCRIPTION OF THE INVENTION
The present invention is a system and method for tracking and locating one or more objects or persons carrying or otherwise possessing a locator device. The locator device periodically calculates the present position of the device from signals received from visible or observable radiolocation transmitters, such as fixed radiolocation towers or global positioning system (GPS) satellites. The locator device also maintains or records its previous locations in order to ascertain the distance traveled by the locator device. The locator device periodically communicates its positional data to a server computer via a wireless connection, which is typically a cellular modem. The rate at which the locator device periodically transmits its positional data varies according to the rate the locator device changes its physical position. If the locator device is relatively stationary, the rate of periodic transmission is reduced to thereby conserve the locator device's power consumption. If the locator device is moving rapidly, the rate of period transmission is increase to thereby accurately depict the actual position of the locator device and the person or object in possession of the device. The locator device has software running therein for calculating or otherwise determining the relative movement of the locator device. The server computer maintains positional data received from of all the locator devices participating in the system and makes such positional data available to subscriber users. The system permits subscriber users to retrieve the positional data of objects or persons that the subscriber user wishes to track or locate though subscriber computers. The subscriber computers are linked or otherwise connected to the server computer using standard networking means, such as an Internet connection or a dial-up connection. The locator device includes a power source, such as a battery. Algorithms or routines residing in the locator device provides power saving features and methods to extend the life of the power source.
In its most general terms, the system of the invention comprises a locator device having a receiver for receiving signals from visible radiolocation transmitters, a server computer in wireless communication with the locator device, and a subscriber computer operatively coupled for communication with the server computer. Positional data is calculated by the locator device from signals received from the radiolocation transmitters. This positional data is communicated from the locator device to the server computer, and then communicated from the server computer to the subscriber computers via a network or dial-up connection. The invention provides means for the user of the subscriber computer to ascertain the location or position of persons or objects possession the locator device via the subscriber computers. The invention may also include power saving or conserving algorithms associated with each locator device.
By way of example, and not of limitation, the locator device preferably comprises a radiolocation receiver operatively coupled to a central processing unit (CPU), and a wireless modem operatively coupled to the CPU. Random access memory (RAM) is coupled to the CPU which executes functions and routines associated with the locator device, including, for example, calculating the locator device's position and storing a record or log of the locator device's past positions and locations. Alternatively, a circuit board having the functions and routines described herein for carrying out the CPU functions may be provided. A power s
Sierra Patent Group Ltd.
Urban Edward F.
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