Remote position determination

• US 5,666,647 A
• Filed: 07/18/1996
• Issued: 09/09/1997
• Est. Priority Date: 08/03/1992
• Status: Expired due to Term

• Current Assignee: CDC Propriete Intellectuelle
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Maine, Kristine Patricia
• Primary Examiner(s): Urban, Edward F.
• Assistant Examiner(s): LE, THANH C
• Application Number:
  US08/683,184
• Time in Patent Office: 418 Days
• Field of Search: 455/12.1, 455/13.1, 455/13.2, 455/13.3, 455/13.4, 455/34.1, 455/54.1, 455/56.1, 455/63, 455/67.1, 340/539, 340/988, 340/989, 340/991, 340/993, 342/352, 342/353, 342/350, 342/357
• US Class Current: 455/12.1
• CPC Class Codes: G01S 19/00 Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
• CPC Class Codes: G01S 5/0009 Transmission of position information to remote stations involving assistance data G01S5/0236
• CPC Class Codes: G01S 5/0036 of measured values, i.e. measurement on mobile and position calculation on base station
• CPC Class Codes: G01S 5/0054 of actual mobile position, i.e. position calculation on base station
• CPC Class Codes: G01S 5/12 by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial
• CPC Class Codes: H04B 7/1855 using a telephonic control signal, e.g. propagation delay variation, Doppler frequency variation, power variation, beam identification

Abstract

A constellation of satellites which are distributed around the earth serves as a communications infrastructure that supports autonomous position determination and reporting of that position to a remote location. Satellites continuously broadcast acquisition signals. Position determining units are remotely programmed to activate upon the occurrence of an activation event. If PDUs can capture an acquisition signal, then they engage in activities which lead to determining their position and they coordinate their communications with the requirements of the communications infrastructure. To determine position, a location pulse may be transmitted on a regular schedule. The location pulse is transported between a fast moving satellite and a PDU. The movement of the satellite causes different location pulses to have different propagation delays and Doppler characteristics. By analyzing changes in propagation delays and Doppler characteristics, a procedure determines a position for a PDU.

Claims

1. A method for operating a mobile position determining unit (PDU) in cooperation with a communication system having an orbiting satellite projecting a plurality of communication cells and a monitoring office, said method comprising the steps of:

from one of said plurality of communications cells, receiving an acquisition signal originating from said orbiting satellite, wherein said orbiting satellite projects at least said one of said plurality of communication cells toward the PDU and said acquisition signal includes cell location information which enables determination of at least one cell location of said one of said plurality of communication cells;

cooperatively communicating with said orbiting satellite to exchange at least one location pulse to determine a position of said PDU, wherein said communicating step uses said cell location information to resolve data describing said position; and

transmitting from said PDU to said communication system via said orbiting satellite, said data describing said position of said PDU for immediate delivery to said monitoring office for evaluation of said position.

2. A method as claimed in claim 1 wherein said cooperatively communicating step comprises the steps of:

transmitting a first location pulse and a second location pulse from said PDU for receipt at said satellite, said second location pulse being delayed from said first location pulse by a predetermined amount of time;

measuring data from said first location pulse and said second location pulse; and

said PDU collecting said data used by a processing center for determining said position of said PDU, said processing center being a node in said communication system.

3. A method as claimed in claim 1 additionally comprising, prior to said receiving step, the step of programming said PDU to become operational upon the occurrence of a predetermined event.

4. A method as claimed in claim 3 wherein said programming step comprises the steps of:

receiving programming data from said communication system; and

storing, in response to said programming data, data which describe conditions to be met prior to said PDU becoming operational.

5. A method as claimed in claim 4 additionally comprising the step of repeating said programming data receiving and storing steps to alter characteristics of said conditions.

6. A method as claimed in claim 3 additionally comprising the steps of:

monitoring, in response to said predetermined event, an environment proximate said PDU; and

transmitting, from said PDU to said communication system, data describing said environment.

7. A method as claimed in claim 1 additionally comprising the steps of:

receiving a command from said communication system which instructs said PDU to transmit non-location data to said communication system; and

transmitting, in response to receipt of said command, said non-location data to said communication system.

8. A method as claimed in claim 7 wherein said non-location data comprises data describing operational parameters of transmissions then-currently being transmitted.

9. A method for tracking mobile objects from a remotely located monitoring office using communication services provided by a communication system having an orbiting satellite projecting a plurality of communication cells, said method comprising the steps of:

physically associating a position determining unit (PDU) with said mobile object;

programming said PDU to become operational upon the occurrence of a predetermined event; and

said PDU determining, in response to said predetermined event, a current position for said PDU by performing the steps of (i) from one of said plurality of communications cells receiving, in response to said predetermined event and prior to said determining step, an acquisition signal originating from said orbiting satellite, wherein said orbiting satellite projects at least said one of said plurality of communication cells toward the PDU and, said acquisition signal includes cell location information which enables determination of at least one cell location of said at least one communication cell;

(ii) exchanging at least one location pulse with said satellite;

(iii) determining data describing a position for said PDU using said at least one location pulse;

(iv) resolving said data describing said position using said cell location information; and

(v) transmitting from said PDU to said communication system via said orbiting satellite, said data describing said position of said PDU for immediate delivery to said monitoring office for evaluation of said position.

10. A method as claimed in claim 9 wherein said orbiting satellite moves in space relative to said PDU, and said determining step comprises the step of said PDU transmitting, in response to said acquisition signal, a first location pulse and a second location pulse from said PDU for receipt at said communication system, said second location pulse being delayed from said first location pulse by a predetermined amount of time to allow said first location pulse and said second location pulse to be transmitted by said PDU when said satellite is located at two different positions in space.

11. A method as claimed in claim 9 additionally comprising the step of delivering data describing said position of said PDU through said communication system to said monitoring office.

12. A method as claimed in claim 9 wherein said communication system includes a constellation of orbiting satellites distributed around the earth, wherein said at least one location pulse are exchanged within a predetermined portion of a radio frequency spectrum, and said method comprises the steps of:

reusing said portion of said radio frequency spectrum at diverse locations proximate the surface of the earth to carry other communications occurring simultaneously with said at least one location pulse; and

locating said PDU in a predominantly rural area so that said other communications may take place in a predominantly urban area.

13. A method as claimed in claim 9 wherein said programming step comprises the steps of:

transmitting programming data through said communication system to said PDU; and

storing, in response to said programming data, data which describe conditions to be met prior to said PDU becoming operational.

14. A method as claimed in claim 13 additionally comprising the step of repeating said transmitting and storing steps to alter characteristics of said conditions.

15. A method as claimed in claim 9 additionally comprising the steps of:

monitoring, in response to said predetermined event, an environment proximate said PDU; and

transmitting, from said PDU to said communication system, data describing said environment.

16. A method as claimed in claim 9 additionally comprising the steps of:

receiving, at said PDU, a command from said communication system which instructs said PDU to transmit non-location data to said communication system; and

transmitting, from said PDU in response to receipt of said command, said non-location data to said communication system.

17. An integrated telecommunication system for transporting voice communications and for transporting data communications between a monitoring office and remotely located mobile objects to aid in the location of said objects, said system comprising:

a constellation of radio communication stations orbiting the earth, wherein said radio communication stations project a plurality of communication cells with at least one communication cell toward the mobile objects;

a population of first subscriber units configured to engage in voice communications through said constellation;

a population of second subscriber units configured to engage in data communications through said constellation, each second subscriber unit being configured in cooperation with at least a portion of said radio communication stations to exchange at least one location pulse which is used to generate data which describe a location of said second subscriber unit, wherein an acquisition signal which originates from one of said plurality of communication cells of one of said radio communication stations includes cell location information of said one of said plurality of communication cells, said cell location information being used to resolve said location of said second subscriber unit; and

means, in data communication with at least a portion of said radio communication stations, for transmitting immediately from said second subscriber unit to said monitoring office via said radio communication station for evaluation of said position, said location data describing said position of said second subscriber unit as cooperatively generated between said second subscriber unit and said radio communication stations.

18. A system as claimed in claim 17 wherein said radio communication stations are configured in cooperation with said first and second subscriber units so that said first and second subscriber units use substantially the same radio frequency spectrum.

19. A system as claimed in claim 17 wherein each of said second subscriber units comprises:

a memory device;

a transceiver; and

a processor coupled to said memory device and said transceiver, said processor being configured to retrieve programming data received at said transceiver, to store said programming data in said memory device, and to control operation of said second subscriber units in response to said programming data.

20. A system as claimed in claim 19 wherein:

said transceiver of each of said second subscriber units comprises a transmitter and a receiver, each of said transmitter and receiver being configured for communication with any one of said radio communication stations;

each of said second subscriber units additionally comprises a battery selectively coupled to said transmitter and to said receiver thereof; and

at least a portion of said programming data instructs said processor to control the coupling of said battery to said transmitter and receiver so that in an inactive mode of operation said battery couples to neither said transmitter nor said receiver, in a stand-by operational mode said battery couples to said receiver, and in a call-in operational mode said battery couples to both said receiver and transmitter.

21. A system as claimed in claim 17 wherein said means for transmitting comprises a processing station in radio communication with said constellation of radio communication stations and coupled to a public switched telecommunications network, said processing station being configured to determine locations from said location data.