Range safety communication system and method utilizing pseudorandom noise sequences

• US 5,937,001 A
• Filed: 06/20/1997
• Issued: 08/10/1999
• Est. Priority Date: 06/20/1997
• Status: Expired due to Fees

• Current Assignee: L-3 Communications Cincinnati Electronics Corporation (L3Harris Technologies, Inc.)
• Original Assignee: L-3 Communications Cincinnati Electronics Corporation (L3Harris Technologies, Inc.)
• Inventors: Shockey, Bruce Edward
• Primary Examiner(s): Ghebretinsae, Temesghen
• Application Number:
  US08/880,053
• Time in Patent Office: 781 Days
• Field of Search: 375/200, 375/206-210, 375/211, 375/259, 375/271, 375/279-281, 375/295, 375/302, 375/308, 375/316, 375/322, 375/324, 375/326, 375/329, 375/331, 375/332, 375/340 , 375/343, 375/362, 375/365, 375/367, 375/377, 370/206, 370/207, 370/215, 370/315, 370/316, 455/7, 455/11.1, 455/12.1, 455/60, 455/228, 455/344, 455/345, 329/304, 332/103, 340/500, 340/501, 340/825.06, 340/825.14, 340/825.18, 340/825.3, 340/825.57, 340/825.58, 340/425.1, 244/3.1, 244/3.11, 244/3.14, 89/1.1, 89/1.11, 701/1-3, 701/36, 701/45, 701/99, 701/120, 701/122
• US Class Current: 375/142
• CPC Class Codes: H04B 1/69 Spread spectrum techniques

Abstract

A system and method for transmitting one or more range safety commands to a launch vehicle which includes transmitting structure having a pilot code generator and at least one additional code generator for generating at least one transmitter command code corresponding to a range safety command. A PN clock continuously locks the one or more transmitter command codes with the transmitter pilot code. Sequence selection structure selectively applies the one or more transmitter command codes to a modulator which combines the transmitter pilot code and the applied transmitter command codes with a carrier signal, and transmits the pilot and command codes through a relay satellite to the vehicle. Receiving structure in the vehicle recovers the pilot and command codes, and aligns a locally generated pilot code with the recovered pilot code. At least one local command code generator, which is synchronized to the local pilot code, is included in the receiving structure for generating one or more local command codes which correspond to the transmitter command codes. The local command codes and recovered transmitter command codes are sampled, and the samples compared over an acquisition period. If at the end of an acquisition period any set of samples exceeds a predetermined level of correspondence, then a hit detect signal is transmitted to decision logic in the vehicle. If all of the hit detect signals for a command are detected by the decision logic within a predetermined time interval, then the decision logic activates the command.

Claims

1. A method for transmitting one or more range safety command signals from a ground terminal transmitter to a vehicle receiving unit, the method comprising the steps of:

storing identical command codes in the transmitter and receiving unit prior to launch of the vehicle;

generating a transmitter pilot code;

generating one or more transmitter command codes in the transmitter;

applying the transmitter pilot code to a first channel of a modulator in the transmitter according to a clock signal;

selectively applying the one or more transmitter command codes to a second channel of the modulator in the transmitter according to the clock signal, such that the one or more transmitter command codes are synchronized to the transmitter pilot code by the clock signal;

modulating a carrier signal with the pilot and one or more transmitter command codes;

transmitting the modulated carrier signal to the receiving unit;

recovering the one or more transmitter command codes and transmitter pilot code in the receiving unit;

generating a local pilot code in the receiving unit which is synchronized to the transmitter pilot code recovered by the unit;

generating one or more local command codes in the receiving unit;

providing a receiver clock signal in the receiving unit which is aligned with the clock signal in the transmitter;

synchronizing the local command code to the local pilot code using the receiver clock signal;

using the recovered transmitter pilot code, synchronizing the one or more local command codes with the one or more transmitter command codes;

comparing the one or more recovered transmitter command codes with the one or more local command codes to detect the one or more range safety command signals; and

if a detected range safety command signal is equivalent to a destruct command, substantially destroying the vehicle while the vehicle is in flight.

2. The method as recited in claim 1 wherein the transmitter pilot code and the one or more transmitter and local command codes comprise PN sequences.

3. The method as recited in claim 1, wherein the transmitter pilot and command codes are further synchronized by resetting a memory address for the command codes to zero at an epoch of the transmitter pilot code.

4. The method as recited in claim 1, further comprising the step of transmitting the modulated carrier signal through a signal relay.

5. The method as recited in claim 1, wherein the selectively applying step occurs in response to a command request.

6. The method as recited in claim 1, wherein the transmitter pilot and command codes are transmitted to the receiving unit by spread spectrum.

7. A method for transmitting one or more range safety commands from a transmitting structure in a ground station to a receiving structure in a launch vehicle, the method comprising the steps of:

storing identical command PN sequences in the transmitting and receiving structures prior to launch of the vehicle;

generating a transmitter pilot code;

generating a plurality of distinct transmitter command PN sequences, each of the transmitter command PN sequences corresponding to one of the range safety commands and having a period equal to and synchronized with the period of the transmitter pilot code according to a clock frequency in the transmitting structure;

applying the transmitter pilot code to a first channel of a modulator;

selectively applying one or more of the transmitter command PN sequences to a second channel of the modulator;

modulating a carrier signal with the transmitter pilot code and the one or more transmitter command PN sequences applied to the modulator;

transmitting the modulated carrier signal to the receiving structure through a signal relay;

recovering the one or more transmitter command PN sequences and the transmitter pilot code in the receiving structure;

generating one or more local command PN sequences in the receiving structure;

generating a local pilot code in the receiving structure;

synchronizing the one or more local PN sequences to the local pilot code according to the clock frequency;

using the recovered transmitter pilot code, synchronizing the one or more local command PN sequences to the one or more recovered transmitter command PN sequences; and

comparing the recovered one or more transmitter command PN sequences with each of the local command PN sequences to detect the one or more range safety commands.

8. The method as recited in claim 7, wherein the step of comparing the recovered one or more transmitter command PN sequences and local command PN sequences includes,

sampling the recovered transmitter command PN sequences,

multiplying each of the transmitter command PN sequence samples with at least a bit of each of the local command PN sequences to form products associated with the local command PN sequences,

separately summing the products of the transmitter command PN sequence samples and the at least one bit of each of the local command PN sequences during an acquisition period, and

comparing each sum to a predetermined threshold at the end of the acquisition period to detect the one or more range safety commands.

9. The method as recited in claim 7, wherein one or more of the transmitter command PN sequences are applied to the modulator in response to a command request.

10. A communications system for transmitting one or more commands between a ground terminal and a launch vehicle, the system comprising:

transmitting structure associated with the ground terminal, the transmitting structure comprising,

a first code generator adapted to generate a transmitter pilot code,

at least one additional code generator, each additional code generator adapted to generate a transmitter command code,

a timing control adapted to provide a clock signal to continuously lock the transmitter command codes with the transmitter pilot code, and

a modulator adapted to combine the transmitter pilot code and one or more transmitter command codes with a carrier signal to provide a modulated command signal;

a communications link adapted to transmit the modulated command signal;

receiving structure located in the launch vehicle adapted to receive and demodulate the modulated command signal, the receiving structure comprising,

a second code generator adapted to generate a local pilot code,

a receiver adapted to recover the transmitter pilot and command codes and to align the local pilot code with the recovered transmitter pilot code; and

at least one local command code generator, aligned to the local pilot code, and adapted to generate one or more local command codes corresponding to the transmitter command codes to detect the commands; and

a pyrotechnic in the launch vehicle adapted to substantially destroy the launch vehicle during flight upon detection of a destruction command by the receiving structure.

11. The system as recited in claim 10, wherein the transmitter pilot code and at least one transmitter command code comprise distinct PN sequences.

12. The system as recited in claim 11, wherein the transmitter command PN sequences represent range safety commands for the launch vehicle.

13. The system as recited in claim 10, further comprising selection structure for selectively applying at least one transmitter command code to the modulator.

14. The system as recited in claim 13, wherein the selection structure further comprises a sequence timer for selectively applying the command codes to the modulator at predetermined intervals.

15. The system as recited in claim 10, wherein the modulator and receiver are adapted for QPSK spread spectrum communications.

16. The system as recited in claim 10, wherein the communications channel includes a relay satellite.

17. A method for transmitting one or more command signals from a ground terminal to a vehicle, the method comprising the steps of:

generating a transmitter pilot code;

generating one or more transmitter command codes;

applying the transmitter pilot code to a first channel of a modulator;

selectively applying the one or more transmitter command codes to a second channel of the modulator;

modulating a carrier signal with the pilot and one or more transmitter command codes;

transmitting the modulated carrier signal to a receiver;

recovering the one or more transmitter command codes and transmitter pilot code in the receiver;

generating one or more local command codes;

using the recovered transmitter pilot code, synchronizing the one or more local command codes with the transmitter command codes; and

comparing the one or more recovered transmitter command codes with the one or more local command codes to detect the one or more command signals, wherein at least one transmitter command code is synchronized to the transmitter pilot code by resetting a memory address for the command codes to zero at an epoch of the transmitter pilot code.

18. A communications system for transmitting one or more commands between a ground terminal and a launch vehicle, the system comprising:

transmitting structure associated with the ground terminal, the transmitting structure comprising,

a first code generator for generating a transmitter pilot code,

at least one additional code generator, each additional code generator generating a transmitter command code,

a timing control for continuously locking the transmitter command codes with the transmitter pilot code, and

a modulator for combining the transmitter pilot code and one or more transmitter command codes with a carrier signal to provide a modulated command signal;

a communications link for transmitting the modulated command signal;

receiving structure located in the launch vehicle for receiving and demodulating the modulated command signal, the receiving structure comprising,

a second code generator for generating a local pilot code,

a receiver for recovering the transmitter pilot and command codes and aligning the local pilot code with the recovered transmitter pilot code; and

at least one local command code generator, aligned to the local pilot code, for generating one or more local command codes corresponding to the transmitter command codes to detect the commands;

selection structure for selectively applying at least one transmitter command code to the modulator, wherein the selection structure further comprises a sequence timer for selectively applying the command codes to the modulator at predetermined intervals.

19. A communications system for transmitting one or more commands between a ground terminal and a launch vehicle, the system comprising:

transmitting structure associated with the ground terminal, the transmitting structure comprising,

a first code generator for generating a transmitter pilot code,

at least one additional code generator, each additional code generator generating a transmitter command code,

a timing control for continuously locking the transmitter command codes with the transmitter pilot code, and

a modulator for combining the transmitter pilot code and one or more transmitter command codes with a carrier signal to provide a modulated command signal;

a communications link for transmitting the modulated command signal; and

,

receiving structure located in the launch vehicle for receiving and demodulating the modulated command signal, the receiving structure comprising,

a second code generator for generating a local pilot code,

a receiver for recovering the transmitter pilot and command codes and aligning the local pilot code with the recovered transmitter pilot code; and

at least one local command code generator, aligned to the local pilot code, for generating one or more local command codes corresponding to the transmitter command codes to detect the commands;

wherein the modulator and receiver are adapted for QPSK spread spectrum communications.