Robust and resilient timing architecture for critical infrastructure

Patent metadata

Field	Value
Publication number	US-10775749-B2
Application number	US-201514690225-A
Country	US
Kind code	B2
Filing date	Apr 17, 2015
Priority date	Apr 17, 2015
Publication date	Sep 15, 2020
Grant date	Sep 15, 2020

Abstract

A device for transmitting synchronized timing including a receiver, a transmitter, one or more processors, memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the programs including instructions for receiving through the receiver a timing signal comprising first time information that is synchronized to a time standard, determining second time information based at least partially on the first time information, composing a message formatted in accordance with a global navigation satellite system (GNSS) standard, wherein the message comprises the second time information, and transmitting the message through the transmitter on a radio signal having a frequency in the frequency modulation (FM) radio frequency band.

First claim

What is claimed as new and desired to be protected by Letters Patent of the United States is:

1. A device for transmitting synchronized timing comprising:
a receiver, wherein the receiver is configured to receive a timing signal from a ground-based reference clock;
a transmitter;
a clock, wherein the clock is configured to generate a clock signal;
a time interval counter tester, wherein the time interval counter tester is configured to compare timing information from a plurality of sources to determine the performance of the receiver and the transmitter;
a two-way time and frequency transfer (TWFTFT) unit, wherein the TWFTFT unit is configured to exchange timing information between the receiver and the ground-based reference clock;
one or more processors;
memory; and
one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the programs including instructions for:
receiving through the receiver the timing signal comprising first time information that is synchronized to a time standard;
adjusting a timing information at the receiver and frequency information of the clock signal based on the received first time information;
determining second time information based on the adjusted timing and frequency information of the clock signal;
transmitting the second time information from the receiver to the transmitter;
composing a message formatted in accordance with a global navigation satellite system (GNSS) standard at the transmitter, wherein the message comprises the second time information and a pseudorandom noise code unique to the device;
transmitting the message through the transmitter on a signal having a frequency in a frequency modulation (FM) radio frequency band; and
comparing the timing signal from the ground-based clock with a timing signal received from a GPS receiver using the time interval counter tester to determine the performance of the transmitter and the receiver.

2. The device of claim 1 , wherein the time standard is Coordinated Universal Time (UTC).

3. The device of claim 1 , wherein the synchronization of the first time information to the time standard is accurate to within 10 nanoseconds.

4. The device of claim 1 , wherein the first time information is independent of a GNSS.

5. The device of claim 1 , wherein the receiver is configured to receive the timing signal over fiber optic cable from the ground-based reference clock.

6. The device of claim 1 , wherein the second time information is synchronized to the time standard and the synchronization is accurate to within 500 nanoseconds.

7. The device of claim 1 , wherein the message further comprises a location of the device.

8. The device of claim 1 , wherein the transmitter is configured to simultaneously transmit the message on two signals having frequencies in the FM radio frequency band.

9. The device of claim 1 , further including instructions stored within the memory for encrypting the message prior to transmitting the message through the transmitter.

10. The device of claim 1 , wherein the message comprises at least one of a time-of-week information and clock correction information.

11. A method comprising:
an electronic device with a processor, a clock configured to generate a clock signal, a receiver, and a transmitter:
receiving through the receiver a timing signal from a ground-based reference clock comprising first time information that is synchronized to a time standard wherein a two-way time and frequency (TWFTFT) unit is used to exchange the first time information between the receiver and the ground-base reference clock;
adjusting a timing information and frequency information of the clock signal at the receiver based on the received first time information;
determining second time information at the receiver based on the adjusted timing and frequency information of the clock signal;
transmitting the second time information from the receiver to the transmitter;
composing a message formatted in accordance with a GNSS standard at the transmitter, wherein the message comprises the second time information and a pseudorandom noise code unique to the device;
transmitting the message through the transmitter on a signal having a frequency in an FM radio frequency band; and
comparing the timing signal from the ground-based clock with a timing signal received from a GPS receiver using a time interval counter tester to determine the performance of the transmitter and the receiver.

12. The method of claim 11 , wherein the time standard is UTC.

13. The method of claim 11 , wherein the synchronization of the first time information to the time standard is accurate to within 10 nanoseconds.

14. The method of claim 11 , wherein the first time information is independent of a GNSS.

15. The method of claim 11 , wherein the receiver is configured to receive the timing signal over fiber optic cable from the ground-based reference clock.

16. The method of claim 11 , wherein the second time information is synchronized to the time standard and the synchronization is accurate to within 500 nanoseconds.

17. The method of claim 11 , wherein the message further comprises a location of the device.

18. The method of claim 11 , wherein the transmitter is configured to simultaneously transmit the message on two signals having frequencies in the FM radio frequency band.

19. The method of claim 11 , further comprising encrypting the message prior to transmitting the message through the transmitter.

20. The method of claim 11 , wherein the message comprises at least one of time-of-week information and clock correction information.

21. A receiving device comprising:
a first receiver;
a second receiver, wherein the second receiver is configured to receive a second signal;
a transmitter;
one or more processors;
memory; and
one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the programs including instructions for:
receiving through the first receiver a first signal having a frequency in an FM radio frequency band from a transmitting device, the first signal comprising a message formatted in accordance with a GNSS standard and including a pseudorandom noise code unique to the transmitting device;
extracting first time information from the message;
determining second time information based on the first time information and a pre-determined distance between the receiving device and the transmitting device, wherein the second time information is synchronized to a time standard;
generating a timing signal based at least partially on the second time information; and
transmitting the timing signal through the transmitter, wherein transmitting the timing signal includes transmitting the signal to a time interval counter tester, wherein the time interval counter tester is configured to compare a timing signal from a ground-based clock with a timing signal received from a GPS receiver and the timing signal transmitted through the transmitter to determine the performance of a synchronized timing system.

22. The receiving device of claim 21 , wherein the synchronization of the second time information is accurate to within 10 microseconds relative to the time standard.

23. The receiving device of claim 21 , wherein the receiver is configured to simultaneously receive two signals having frequencies in an FM radio

Assignees

• Mitre Corp

Inventors

• Dunn Jeffrey
• Mckenna Sean
• Martin Cynthia E
• Cohen Michael L

Classifications

• G04G7/00 Primary

  Synchronisation (radio-controlled time-pieces G04R) · CPC title

• G04R20/02

  the radio signal being sent by a satellite, e.g. GPS · CPC title