GPS based search and rescue system

• US 5,847,679 A
• Filed: 06/17/1997
• Issued: 12/08/1998
• Est. Priority Date: 03/04/1992
• Status: Expired due to Term

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Yee, David Moon, Zucarelli, Philip John, Bickley, Robert Henry, Brenner, Charles Herbert, Keller, Theodore Wolley, Moyer, Christopher Kent
• Primary Examiner(s): Blum, Theodore M.
• Application Number:
  US08/877,592
• Time in Patent Office: 539 Days
• Field of Search: 342/357, 701/213, 701/214
• US Class Current: 342/357.31
• CPC Class Codes: G01S 19/07 providing data for correcting measured positioning data, e.g. DGPS [differential GPS] or ionosphere corrections
• CPC Class Codes: G01S 19/071 DGPS corrections
• CPC Class Codes: G01S 19/17 Emergency applications
• CPC Class Codes: G01S 19/18 Military applications
• CPC Class Codes: G01S 2205/002 for traffic control, mobile tracking, guidance, surveillance or anti-collision
• CPC Class Codes: G01S 2205/006 for emergency situations
• CPC Class Codes: G01S 2205/008 using a mobile telephone network
• CPC Class Codes: G01S 5/0027 of actual mobile position, i.e. position determined on mobile
• CPC Class Codes: G01S 5/0081 Transmission between base stations
• CPC Class Codes: H04B 7/18504 Aircraft used as relay or high altitude atmospheric platform

Abstract

A GPS based search and rescue system utilizes an airborne interrogation unit for extending the range of a second interrogation unit. The airborne unit relays communication between a survival radio and the second interrogation unit. The second interrogation unit is typically a ground based unit and is arranged to provide GPS correction information to the survival radio. The normal line of sight communication between a survival radio and an interrogation unit is extended to an over the horizon communication path by utilizing the airborne interrogation unit as a relay for communications.

Claims

1. A Search and Rescue System comprising:

at least one survival radio, said survival radio comprising a GPS module for obtaining GPS derived location information and a transceiver for providing Line of Sight (LOS) communications to transmit said location information in response to receipt of an interrogation signals;

a first interrogation unit, said first interrogation unit having apparatus for sending interrogation signals to said survival radio to cause said survival radio to transmit said GPS derived location information signals, said interrogation signals being sent via a substantially Line of Sight (LOS) first communication link to said survival radio, said GPS derived location information signals being received from said survival radio over said first communication link, wherein said first interrogation unit is carried on an airborne vehicle;

at least one second interrogation unit, said second interrogation unit having apparatus for sending second interrogation signals to said first interrogation unit via a substantially LOS second communication link, said second communication link being between said first interrogation unit and said second interrogation unit, said first and second interrogation units being cooperatively operable such that said first interrogation unit relays information between said second interrogation unit and said survival radio such that substantially Over the Horizon (OTH) communication is obtainable between said survival radio and said second interrogation unit over said first and second communication links, at least part of said information comprising GPS derived location information identifying the location of said survival radio.

2. A search and Rescue System in accordance with claim 1, wherein:

said first interrogation unit is carried on an unmanned airborne vehicle.

3. Search and Rescue System in accordance with claim 1, wherein:

said second interrogation unit is at a ground based location, said second interrogation unit including apparatus to provide GPS correction information to said first interrogation unit.

4. A Search and Rescue System in accordance with claim 3, wherein:

said first interrogation unit transmits said GPS correction information to said survival radio.

5. A Search and Rescue System in accordance with claim 1, wherein:

said at least one survival radio includes means for selecting one of a plurality of stored messages for delivery to said first interrogation unit.

6. A Search and Rescue System in accordance with claim 5, wherein:

said survival radio includes in each message transmitted an identification code to uniquely identify said survival radio.

7. A Search and Rescue System, comprising:

a survival radio, said survival radio comprising a GPS receiver, a transceiver, and a controller, said survival radio having a unique identification code associated therewith, said survival radio controller responding to interrogation messages received over a substantially line of sight first communication path by said transceiver and having contained therein said unique identification code by causing said transceiver to transmit location information generated by said GPS receiver and said identification code over said first communication path;

a first interrogation unit comprising a second controller and a second transceiver, said second controller being operable to cause said second transceiver to transmit interrogation messages containing said survival radio identification code, said second controller being further operable to identify messages received by said second transceiver as being from said survival radio; and

a second interrogation unit comprising a third controller and a third transceiver, said third controller being operable to cause said third transceiver to generate said interrogation messages and to transmit said interrogation messages to said first interrogation unit, said first interrogation unit being responsive to said interrogation messages to re-transmit said interrogation messages to said survival radio, at least some of said interrogation messages including GPS position correction data that can be used by said survival radio to correct a local position determined by said GPS receiver, said at least some interrogation messages being among said interrogation messages that are re-transmitted to said survival radio to cause said survival radio to transmit said location information over said first communication path.

8. A Search and Rescue System in accordance with claim 7, comprising:

a substantially Line of Sight (LOS) first communication path between said survival radio and said first interrogation unit; and

a substantially LOS second communication path between said first interrogation unit and said second interrogation unit.

9. A Search and Rescue System in accordance with claim 8, wherein:

said first communication path and said second communication path are operable to provide an Over the Horizon (OTH) communication path between said survival radio and said second interrogation unit.

10. A Search and Rescue System in accordance with claim 7, comprising:

a third GPS receiver in said second interrogation unit;

where in said third controller generates said GPS correction data from GPS information obtained from said third GPS receiver and data pertaining to the geographic location of said second interrogation unit.

11. A Search and Rescue System in accordance with claim 7, wherein:

said GPS correction data includes GPS differential correction data.

12. A method of operating a Search and Rescue system, said system comprising at least one survival radio, at least one first interrogation unit, and a second interrogation unit, said method comprising the steps of:

generating an interrogation message at said second interrogation unit, said interrogation message containing a unique identification code corresponding to a first survival radio;

transmitting said interrogation message to said first interrogation unit, wherein said first interrogation unit is carried on an airborne vehicle;

utilizing said first interrogation unit to relay said interrogation message to said first survival radio;

responding to said interrogation message, at said first survival radio, by generating and transmitting a response message containing said unique identification code and geographic location information;

receiving said response message at said first interrogation unit; and

relaying said response message from said first interrogation unit to said second interrogation unit.

13. A method in accordance with claim 12, comprising:

receiving at said survival radio GPS signals and generating said geographic location information from said GPS signals.

14. A method in accordance with claim 13, comprising:

generating at said second interrogation unit GPS correction information and transmitting said GPS correction information to said survival radio via said first interrogation unit.

15. A method in accordance with claim 14, comprising:

receiving GPS signals at said second interrogation unit and determining said GPS correction information from said GPS signals and data pertaining to the geographic location of said second interrogation unit.

16. A method in accordance with claim 12, wherein:

said step of generating an interrogation message includes encoding said interrogation message using an error correction code.

17. A method in accordance with claim 12, wherein:

said step of generating an interrogation message includes utilizing bit interleaving.

18. A method in accordance with claim 15, comprising:

receiving GPS signals at said first interrogation unit and determining the position of said first interrogation unit from said GPS signals.

19. A method in accordance with claim 14, comprising:

using said GPS correction information at said first interrogation unit to determine the position of said first interrogation unit.

20. A method in accordance with claim 15, comprising:

operating said second interrogation unit at a fixed ground based location during the duration of a search.