System for continuously establishing and indicating the location of a movable object

• US 4,884,208 A
• Filed: 05/16/1988
• Issued: 11/28/1989
• Est. Priority Date: 05/16/1988
• Status: Expired due to Fees

• Current Assignee: Equipment Tracking Network Incorporated
• Original Assignee: Equipment Tracking Network Incorporated
• Inventors: Rector, Mark, Marinelli, Orlando M.
• Primary Examiner(s): Lall, Parshotam S.
• Assistant Examiner(s): Black, Thomas G.
• Application Number:
  US07/194,597
• Time in Patent Office: 561 Days
• Field of Search: 364/460, 364/443, 364/449, 364/452, 364/459, 342/450, 342/451, 342/457, 340/910, 340/917, 340/989, 340/992
• US Class Current: 701/300
• CPC Class Codes: G01S 5/0009 Transmission of position information to remote stations involving assistance data G01S5/0236
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: G07C 5/008 communicating information to a remotely located station transmission systems for measured values G08C
• CPC Class Codes: G08G 1/205 Indicating the location of the monitored vehicles as destination, e.g. accidents, stolen, rental
• CPC Class Codes: G09B 29/106 using electronic means

Abstract

A system for continuously establishing and indicating the location of a movable object comprises a first transmitter secured to the object for periodically transmitting, at a first predetermined frequency, first radio frequency signals representative of an identification code uniquely associated with the object. A plurality of receiver/repeater stations are positioned at spaced locations within a predetermined geographic area, each receiver/repeater station including a plurality of spaced receivers for receiving and demodulating the first radio frequency signals to provide an object identification code signal and a device associated with each first receiver for determining the strength of the received first radio frequency signal and for generating a strength signal for each receiver. Signal processor circuitry and a computer are centrally located within the predetermined geographic area in communication with the first receiver and the strength determining device for receiving the signals representative of the object identification code and the strength signals, for calculating the location of the object based upon the strength signals and for storing signals representative of the object identification code and the location of the object. A master tracking station is in communication with the signal processing circuitry and computer for each of a plurality of predetermined geographic areas. The master tracking station receives and stores the signals representative of the object identification code and the object location and provides a visual indication of the object identification code and object location.

Claims

1. A system for continuously establishing and indicating the location of a movable object comprising:

first transmitter means secured to the object for periodically transmitting, at a first predetermined frequency, first radio frequency signals representative of an identification code uniquely associated with the object;

a plurality of receiver/repeater stations positioned at spaced locations within a predetermined geographic area, each receiver/repeater station including, a plurality of spaced, first receiver means for each receiving and demodulating the first radio frequency signals to provide an object identification code signal, means associated with each first receiver means for determining the strength of the received first radio frequency signals and for generating a first radio signal frequency strength signal in each first receiver means, and second transmitter means connected to each of the spaced first receiver means and to the signal strength determining means for transmitting, at a second predetermined frequency, second radio frequency signals representative of the object identification code and the strength signals;

second receiver means centrally located within the predetermined geographic area for receiving and demodulating the second radio frequency signals to provide signals representative of the object identification code and the strength signals;

signal processor and computer means connected to the second receiver means for receiving the signals representative of the object identification code and strength signals, for calculating the location of the object based upon the strength signals, and for storing signals representative of the object identification code and the location of the object;

third transmitter means connected to the signal processor and computer means for receiving the signals representative of the object identification code and the object location and for transmitting, at a third predetermined frequency, third radio frequency signals representative of the object identification code and the object location; and

a master tracking station for receiving information from a plurality of predetermined geographic areas including, third receiver means for receiving and demodulating the third radio frequency signals to provide signals representative of the object identification code and the object location, storage means connected to the third receiver means for receiving and storing the signals representative of the object identification code and the object location, and display means for receiving the stored object identification code and object location signals and for providing a visual indication of the object identification code and the object location.

2. A system for continuously establishing and indicating the location of a movable object comprising:

first transmitter means secured to the object for periodically transmitting, at a first predetermined frequency, first radio frequency signals representative of an identification code uniquely associated with the object;

a plurality of receiver/repeater stations positioned at spaced locations within a predetermined geographic area, each receiver/repeater station including, a plurality of spaced, first receiver means for each receiving and demodulating the first radio frequency signals to provide an object identification code signal, means associated with each first receiver means for determining the strength of the received first radio frequency signals and for generating a first radio frequency strength signal in each first receiver means;

signal processor and computer means centrally located within the predetermined geographic area and communicating with the first receiver means and the strength determining means for receiving the signals representative of the object identification code and strength signals, for calculating the location of the object based upon the strength signals and for storing signals representative of the object identification code and the location of the object; and

a master tracking station communicating with the signal processor and computer means for each of a plurality of predetermined geographic areas, the master tracking station including means for receiving and storing the signals representative of the object identification code and the object location, and display means for providing a visual indication of the object identification code and the object location.