Method and system for autonomous two-way radio frequency communication

• US 6,546,259 B1
• Filed: 06/20/2000
• Issued: 04/08/2003
• Est. Priority Date: 06/20/2000
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Vendryes, Robert S.
• Primary Examiner(s): Hunter, Daniel
• Assistant Examiner(s): Nguyen, Thuan T.
• Application Number:
  US09/595,915
• Time in Patent Office: 1,022 Days
• Field of Search: 455/513, 455/445, 455/447, 455/448, 455/449, 455/524, 455/67.1, 455/67.3, 455/115, 455/427, 455/428, 455/429, 455/430, 455/431
• US Class Current: 455/513
• CPC Class Codes: H04B 7/0608 Antenna selection according to transmission parameters
• CPC Class Codes: H04B 7/18506 Communications with or from aircraft, i.e. aeronautical mobile service
• CPC Class Codes: H04B 7/18508 with satellite system used as relay, i.e. aeronautical mobile satellite service

Abstract

A method and system for autonomous two-way RF communication between a launch vehicle and at least one receiving or tracking station. Detection circuitry continuously determines the identity of the optimum receiving or tracking station (ground, sea, airborne, or satellite) and selects the best launch vehicle transmission antenna to close the RF telemetry link. The method and system is designed to simultaneously transmit and receive RF signals. The antenna system includes a telemetry transmission link and an antenna selection link. Antenna selection link signals received by each antenna element on the launch vehicle are provided via RF couplers to a receiver for signal strength and modulation signal detection. The telemetry transmission link communicates with a receiving or tracking station by using a transmitter to drive one of two or more switched antennas mounted on the surface of the launch vehicle having the current higher signal strength.

Claims

1. A method for autonomous two-way radio frequency communications between at least one first station and a second station, wherein the at least one first station is adapted to transmit at least one unique radio frequency signal to the second station, said method comprising the steps of:

(a) transmitting the at least one unique radio frequency signal from the at least one first station;

(b) receiving the at least one unique radio frequency signal with at least first and second antennas located on the second station;

(c) determining which of said at least first and second antennas receiving the at least one unique radio frequency signal has a higher signal strength;

(d) connecting a transmitter located on the second station to one of said at least first and second antennas determined to have received the at least one unique radio frequency signal having said higher signal strength; and

(e) transmitting using said transmitter a first telemetry signal of monitored parameters of the second station over one of said at least first and second antennas connected to said transmitter.

2. A method according to claim 1 further comprising the step of:

(f) receiving said first telemetry signal of monitored parameters of the second station in the at least one first station determined to have transmitted the at least one unique radio frequency signal received in said at least first and second antennas having said higher signal strength.

3. A method according to claim 2 further comprising the step of:

(g) repeating steps (a) through (f) for a next unique radio frequency signal transmitted from the at least one first station to the second station.

4. A method according to claim 1 wherein said determining step comprises the steps of:

determining a first signal strength for the at least one unique radio frequency signal received in said first antenna;

determining a second signal strength for the at least one unique radio frequency signal received in said second antenna; and

determining which of said first and second signal strengths is said higher signal strength.

5. A method according to claim 1 wherein said determining step comprises the steps of:

determining a first charge on a first capacitor induced by the at least one unique radio frequency signal received in said first antenna;

determining a second charge on a second capacitor induced by the at least one unique radio frequency signal received in said second antenna; and

determining which of said first and second charges has a higher charge, wherein said higher charge indicates which of said at least first and second antennas receiving the at least one unique radio frequency signal has said higher signal strength.

6. A method according to claim 1 wherein the at least one first station is one of a ground station and a non-ground station.

7. A method according to claim 1 wherein the second station is moving relative to the at least one first station.

8. A method according to claim 1 wherein said receiving step comprises the step of:

routing the at least one unique radio frequency signal received in said at least first and second antennas to a receiver through a receiver switch, wherein said receiver switch is connectable between said at least first and second antennas and said receiver.

9. A method according to claim 8 wherein said receiver switch is adapted to switch between said at least first and second antennas.

10. A method according to claim 8 wherein said receiver switch is adapted to transfer the at least one unique radio frequency signal received in said at least first and second antennas to said receiver.

11. A method according to claim 8 wherein said receiving step comprises the steps of:

receiving the at least one unique radio frequency signal in said first antenna;

connecting said first antenna to said receiver with said receiver switch for a selected amount of time;

routing the at least one unique radio frequency signal from said first antenna to said receiver with said receiver switch during said selected amount of time;

receiving the at least one unique radio frequency signal in said second antenna;

connecting said second antenna to said receiver with said receiver switch for said selected amount of time; and

routing the at least one unique radio frequency signal from said second antenna to said receiver with said receiver switch during said selected amount of time.

12. A method according to claim 11 wherein said determining step comprises the steps of:

determining a first signal strength for the at least one unique radio frequency signal received during said selected amount of time;

storing said first signal strength in a memory in said processor;

determining a second signal strength for the at least one unique radio frequency signal received in said second antenna during said selected amount of time;

storing said second signal strength in said memory in said processor; and

comparing said first signal strength stored in said memory to said second signal strength stored in said memory to determine which of said first and second signal strengths is said higher signal strength.

13. A method according to claim 12 wherein said connecting step comprises the step of:

inhibiting switching between said at least first and second antennas when a change in said higher signal strength between said at least first and second antennas is less than a selected absolute change amount.

14. A method according to claim 1 wherein the at least one unique radio frequency signal is modulated, and said determining step comprises the steps of:

demodulating the at least one unique radio frequency signal received in said at least first and second antennas to detect a correct handshake bit stream;

when said correct handshake bit stream is detected in said demodulating step, determining a first signal strength for the at least one unique radio frequency signal having said correct handshake bit stream received in said first antenna, and determining a second signal strength for the at least one unique radio frequency signal having said correct handshake bit stream received in said second antenna; and

comparing said first signal strength with said second signal strength to determine which of said first and second signal strengths is said higher signal strength.

15. A method according to claim 1 wherein said transmitter is connected to one of said at least first and second antennas having said higher signal strength with a transmitter switch.

16. A method according to claim 15 wherein said transmitter switch is adapted to switch between said at least first and second antennas.

17. A method according to claim 15 wherein said transmitter switch is adapted to transfer said first telemetry signal of monitored parameters of the second station from said transmitter to said at least first and second antennas.

18. A method according to claim 1 wherein said transmitting step (g) comprises the steps of:

storing temporarily said first telemetry signal of monitored parameters in a memory buffer when a current higher signal strength of a one of said at least first and second antennas is insufficient to maintain a communication link with the at least one first station; and

interleaving said first telemetry signal of monitored parameters stored temporarily in said memory buffer with a subsequent telemetry signal transmitted by said transmitter when said communication link is restored.

19. An apparatus for autonomous two-way radio frequency communications between at least one first station and a second station, wherein the at least one first station is adapted to transmit at least one unique radio frequency signal to the second station, said apparatus comprising:

at least first and second antennas, located on the second station, for at least receiving the at least one unique radio frequency signal transmitted from the at least one first station;

a processor, in communication with said at least first and second antennas, for processing the at least one unique radio frequency signal received in said at least first and second antennas to determine a first signal strength for the at least one unique radio frequency signal received in said first antenna and to determine a second signal strength for the at least one unique radio frequency signal received in said second antenna, and for determining which of said first and second signal strengths is a higher signal strength; and

a transmitter for transmitting a plurality of telemetry signals of monitored parameters of the second station, wherein said transmitter is located on the second station and is connectable to said at least first and second antennas and is in communication with said processor, wherein said processor is adapted to direct said transmitter to transmit said plurality of telemetry signals over one of said at least first and second antennas determined to have received the at least one unique radio frequency signal having said higher signal strength.

20. An apparatus according to claim 19 wherein the at least one first station is one of a ground station and a non-ground station.

21. An apparatus according to claim 19 further comprising:

a first capacitor connectable to said first antenna, wherein a first charge is induced in said first capacitor by the at least one unique radio frequency signal received in said first antenna; and

a second capacitor connectable to said second antenna, wherein a second charge is induced in said second capacitor by the at least one unique radio frequency signal received in said second antenna, and further wherein said processor determines which of said first and second charges has a higher charge, wherein said higher charge indicates which of said at least first and second antennas receiving the at least one unique radio frequency signal has said higher signal strength.

22. An apparatus according to claim 19 wherein the second station is moving relative to the at least one first station.

23. An apparatus according to claim 19 further comprising:

a receiver; and

a receiver switch, connectable between said at least first and second antennas and said receiver, for transferring the at least one unique radio frequency signal received in said at least first and second antennas to said receiver.

24. An apparatus according to claim 23 wherein said receiver switch is adapted to switch between said at least first and second antennas.

25. An apparatus according to claim 23 wherein said receiver switch is adapted to transfer the at least one unique radio frequency signal received in said at least first and second antennas to said receiver.

26. An apparatus according to claim 23, wherein said first antenna is connected to said receiver via said receiver switch for a selected amount of time, and then said second antenna is connected to said receiver via said receiver switch for said selected amount of time, the apparatus further comprising:

a memory buffer for storing said first signal strength determined while said first antenna is connected to said receiver for said selected amount of time, and for storing said second signal strength determined while said second antenna is connected to said receiver for said selected amount of time, and for storing said higher signal strength.

27. An apparatus according to claim 23, wherein the at least one unique radio frequency signal is modulated, the apparatus further comprising:

a demodulator connected to said receiver for demodulating the at least one unique radio frequency signal to detect a correct handshake bit stream therein.

28. An apparatus according to claim 19 further comprising:

a transmitter switch, connectable between said at least first and second antennas and said transmitter, for transferring said plurality of telemetry signals transmitted from said transmitter to said one of said at least first and second antennas determined to have received the at least one unique radio frequency signal having said higher signal strength.

29. An apparatus according to claim 28 wherein said transmitter switch is adapted to switch between said at least first and second antennas.

30. An apparatus according to claim 28 wherein said transmitter switch is adapted to transfer said plurality of telemetry signals to said at least first and second antennas.

31. An apparatus according to claim 28 further comprising:

a means for inhibiting said transmitter switch from switching between said at least first and second antennas when a change in said higher signal strength between said at least first and second antennas is less than a selected absolute change amount.

32. An apparatus according to claim 19 further comprising:

a memory buffer in said processor for temporarily storing a portion of said plurality of telemetry signals when a current higher signal strength of said one of said at least first and second antennas is insufficient to maintain a communication link with the at least one first station; and

a means for interleaving said portion of said plurality of telemetry signals temporarily stored in said memory buffer with a subsequent portion of said plurality of telemetry signals transmitted by said transmitter when said communication link is restored.

33. An apparatus for autonomous two-way radio frequency communications between at least one first station and a second station, wherein the at least one first station is adapted to transmit at least one unique radio frequency signal to the second station, said apparatus comprising:

at least first and second antennas, located on the second station, wherein one of said at least first and second antennas is adapted to scan for and receive the at least one unique radio frequency signal transmitted from the at least one first station;

a processor, in communication with said at least first and second antennas, for processing the at least one unique radio frequency signal received in said one of said at least first and second antennas to determine a best quality signal vector for the at least one unique radio frequency signal; and

a transmitter for transmitting a plurality of telemetry signals of monitored parameters of the second station, wherein said transmitter is located on the second station and is connectable to an other of said at least first and second antennas and is in communication with said processor, wherein said processor is adapted to direct said transmitter to transmit said plurality of telemetry signals over said other of said at least first and second antennas which is adapted to beam said plurality of telemetry signals to the at least one first station in a direction parallel to said best quality signal vector.

34. An apparatus according to claim 33 wherein said at least first and second antennas are phased array antennas.