Method and apparatus for tracking a moving object

• US 5,796,365 A
• Filed: 12/23/1996
• Issued: 08/18/1998
• Est. Priority Date: 03/19/1993
• Status: Expired due to Fees

• Current Assignee: Peter T. Lewis
• Original Assignee: Peter T. Lewis
• Inventors: Lewis, Peter T.
• Primary Examiner(s): Blum, Theodore M.
• Application Number:
  US08/772,509
• Time in Patent Office: 603 Days
• Field of Search: 342/357, 342/363, 342/365, 364/449.7, 343/700 MS, 343/711, 343/713, 343/872, 343/814, 343/816, 343/820, 343/858, 343/865, 343/712
• US Class Current: 342/357.25
• CPC Class Codes: G01S 19/071 DGPS corrections
• CPC Class Codes: G01S 19/36 relating to the receiver frond end
• CPC Class Codes: G01S 19/426 by combining or switching between position solutions or signals derived from different modes of operation in a single system
• CPC Class Codes: G01S 2205/008 using a mobile telephone network
• CPC Class Codes: H01Q 1/325 characterised by the location of the antenna on the vehicle

Abstract

An apparatus and a method are described for determining with a high degree of accuracy the location of an object, based upon signals transmitted from a plurality of satellites rotating about the earth in known orbits. First, the latitude and longitude of a fixed point is determined with accuracy. The object is capable of moving with respect to the fixed point. Second, the satellite signals are received at the fixed point and processed to determine the approximate latitude and longitude of the fixed point. A first difference between the accurate and approximate latitudes is taken to provide a differential latitude correction of a magnitude corresponding to the first difference and of a direction to the north or south. A second difference between the accurate and approximate longitudes is also taken to provide a differential longitude correction of a magnitude corresponding to the second difference and of a direction to the west or east. The satellite signals are received at the object and processed to determine the approximate latitude and longitude of the object. The approximate object latitude and differential latitude correction are then combined to provide a corrected object latitude of improved accuracy, and the approximate object longitude and differential longitude correction are combined to provide a corrected object longitude of improved accuracy.

Claims

1. In an antenna system for use with a plurality of satellite sources, each transmitting at least one positioning signal to at least one object moving about an environment for determining the relative position of the object within the environment, the environment from time-to-time blocking to some degree the transmission of at least one of the positioning signals to the object dependent on the relative position of the object within the environment, said antenna system comprising:

a) a plurality of antenna mounted on the object in a spaced relationship with each other, each of said plurality of antennae capable of receiving a positioning signal to provide a corresponding electrical output signal;

b) a receiver for processing said output signals to facilitate at least in part a determination of the position of the object; and

c) means coupled to each of said plurality of antenna for summing and applying each of said electrical output signals to said receiver and for preventing one of said electrical output signals provided by any one of said plurality of antennae from being applied to any other of said plurality of antennae, whereby said receiver will continue to determine the position of the object when at least one of the positioning signals is at least partially blocked by the environment from at least one of said plurality of antennae.

2. The antenna system as claimed in claim 1, wherein the object is a vehicle and at least two of said plurality of antennae are disposed at opposing extremities of the vehicle.

3. The antenna system as claimed in claim 2, wherein the vehicle has front and rear windows, one of said two antennae is disposed on the front window on the passenger side of the vehicle and the other of said two antennae is disposed on the rear window on the driver side of the vehicle.

4. The antennae system as claimed in claim 1, wherein said coupling means comprise coaxial cables.

5. The antennae system as claimed in claim 1, wherein said coupling means are contained within a housing which is vibration and shock resistant.

6. The antennae system as claimed in claim 1, wherein said coupling means of each of said antennae are of equal length to sum their electrical output signals in phase with each other.

7. In an antenna system for use with a plurality of satellite sources, each transmitting at least one positioning signal to at least one object moving about an environment for determining the relative position of the object within the environment, the environment from time-to-time blocking to some degree the transmission of at least one of the positioning signals to the object dependent on the relative position of the object within the environment, said antenna system comprising:

a) a plurality of antenna mounted on the object in a spaced relationship with each other, each of said plurality of antennae capable of receiving a positioning signal to provide a corresponding electrical output signal;

b) a receiver for processing said output signals to facilitate at least in part a determination of the position of the object; and

c) means coupled to each of said plurality of antenna to receive its output signal and to apply each of said electrical output signals to said receiver in a manner that one of said electrical output signals will not interfere with another of said electrical output signals, whereby said receiver will continue to determine the position of the object when at least one of the positioning signals is at least partially blocked by the environment from at least one of said plurality of antennae, said coupled means includes a diode junction to back bias the electrical output signal from each of said plurality of antennae.

8. In an antenna system for use with a plurality of satellite sources, each transmitting at least one positioning signal to at least one object moving about an environment for determining the relative position of the object within the environment, the environment from time-to-time blocking to some degree the transmission of at least one of the positioning signals to the object dependent on the relative position of the object within the environment, said antenna system comprising:

a) a plurality of antennae mounted on the object in a spaced relationship with each other, each of said plurality of antennae capable of receiving a positioning signal to provide a corresponding electrical output signal exhibits similar electrical characteristics;

b) a receiver for processing said output signals to facilitate at least in part a determination of the position of the object; and

c) means coupled to each of said plurality of antennae to receive its output signal and to apply each of said electrical output signals to said receiver in a manner that one of said electrical output signals will not interfere with another of said electrical output signals, whereby said receiver will continue to determine the position of the object when at least one of the positioning signals is at least partially blocked by the environment from at least one of said plurality of antennae, said coupling means is connected together to sum said electrical output signal from each of said antennae.

9. In an antenna system for use with a plurality of satellite sources, each transmitting at least one positioning signal to at least one object moving about an environment for determining the relative position of the object within the environment, the environment from time-to-time blocking to some degree the transmission of at least one of the positioning signals to the object dependent on the relative position of the object within the environment, said antenna system comprising

a) a plurality of antenna mounted on the object in a spaced relationship with each other, each of said plurality of antennae capable of receiving a positioning signal to provide a corresponding electrical output signal;

b) a receiver for processing said output signals to facilitate at least in part a determination of the position of the object; and

c) means coupled to each of said plurality of antenna to receive its output signal and to apply each of said electrical output signals to said receiver in a manner that one of said electrical output signals will not interfere with another of said electrical output signals, said coupled means includes diode means for receiving said sum of the electrical output signals from said plurality of antennae and for preventing an electrical output signal from one of said plurality of antennae from being applied to another of said antennae, whereby said receiver will continue to determine the position of the object when at least one of the positioning signals is at least partially blocked by the environment from at least one of said plurality of antennae.

10. An antenna adapted to be mounted on a moveable object for receiving a right-hand circularly polarized, satellite electromagnetic transmissions, said antenna comprising:

a) a metallic member, which is configured and dimensioned to receive said right hand circularly polarized electromagnetic transmissions;

b) first and second sheets of an electrical insulating material for receiving therebetween said metal member, said first and second sheets being sealed together to form a unitary assembly enclosing said metallic member, said unitary assembly including an exterior;

c) lead means connected to said metallic member and extending to said exterior of said unitary assembly to output an electrical signal corresponding to the received electromagnetic transmissions; and

d) means for coupling said lead means to said metallic member to ensure that said antenna is right-hand circularly polarized.

11. The antenna of claim 10, wherein said metallic member is of a square configuration.

12. The antenna of claim 11, where said square configuration has a diagonal dimension, said diagonal dimension set to be substantially 1.782 inches in length.

13. The antenna of claim 10, wherein said metallic member is of a circular configuration.

14. The antenna of claim 13, wherein said circular configuration has a diameter, said diameter being set to be substantially 1.782 inches in length.

15. The antenna of claim 10, wherein said metallic member has a center point, said coupling means coupling said lead means to said metallic member at a point offset from said center point to ensure that said antenna is right-hand circularly polarized.

16. The antenna of claim 15, wherein said metallic member has a dividing line passing through its center point and oriented generally in a vertical orientation, said coupling means coupling said lead means to said metallic member disposed to the left of said dividing line as one would view said antenna from the source of the electromagnetic transmissions.

17. The antenna of claim 10, wherein there is included means attached to one of said first and second sheets of insulating material for mounting said antenna on a windshield of the moveable object and indicia is disposed on the other of the first and second sheets of insulating material to disguise the nature of said antenna.

18. The antenna of claims 10, further comprising a communication apparatus coupled to said antenna for receiving from said antenna by said lead means said electrical signal and being adapted for mounting on the object, and wherein said object is capable of moving anywhere within a geographical area, said apparatus comprising:

a) cellular means actuable for transmitting addressed cellular messages;

b) means mounted on the object and coupled to said cellular transmitting means for receiving an addressed prompt message transmitted with an ID simultaneously throughout the geographical area, said cellular receiving means having a unique ID; and

c) means for comparing the ID of the received prompt message with a unique address of said cellular receiving means and, if there is a match, for actuating said cellular transmitting means for transmitting its addressed cellular message.

19. An antenna adapted to be mounted on a moveable object for receiving right-hand circularly polarized, satellite electromagnetic transmissions, the moveable object having a metallic surface with an opening therein, the opening having a circumference, said antenna comprising:

a) a metallic member, which is configured and dimensioned to receive said right-hand circularly polarized, satellite electromagnetic transmissions;

b) first and second sheets of an electrical insulating material for receiving therebetween said metallic member to form an unitary assembly; and

c) means for mounting said unitary assembly within an opening of the metallic surface to be electrically isolated by at least one of said first and second sheets of an electrical insulating material from the circumference to thereby inhibit the reflection of the satellite electromagnetic transmissions by the metallic surface of the moveable object.

20. The antenna of claim 19, wherein said metallic sheet has a periphery which is spaced from the circumference of the metallic surface a sufficient distance to inhibit the undesired reflection.

21. The antenna of claim 20, wherein said satellite electromagnetic transmissions have a predetermined wavelength, and said distance between said periphery of said metallic member and the circumference is set substantially equal to or greater than one-half of the predetermined wavelength.

22. The antenna of claim 21, wherein said distance is 3.74 inches.