US 10,122,487 B2Granted

Time distribution switch

AssigneeSchweitzer Engineering Laboratories, Inc.

InventorsDavid E. Whitehead, Shankar V. Achanta, Henry Loehner

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Abstract

Systems and methods for detecting the failure of a precision time source using an independent time source are disclosed. Additionally, detecting the failure of a GNSS based precision time source based on a calculated location of a GNSS receiver is disclosed. Moreover, the system may be further configured to distribute a time derived from the precision time source as a precision time reference to time dependent devices. In the event of a failure of the precision time source, the system may be configured to distribute a time derived from a second precision time source as the precision time signal during a holdover period.

Claims13

Dependent claims

A time distribution device comprising:

a receiver configured to receive periodic time signals from each of first and second external time sources;
an output configured to provide a precision time signal to an intelligent electronic device (IED), wherein the precision time signal is determined from a best available time source of the first and second external time sources;
a memory;
and a processor operatively coupled to the memory, wherein the processor is configured to execute instructions stored on the memory to cause the processor to:
determine, for the first external time source, a first variation of duration between the periodic time signals from the first external time source, the first variation in duration based on a local oscillator;
determine, for the second external time source, a second variation of duration between the periodic time signals from the second external time source, the second variation in duration based on the local oscillator;
compare the first time source and the second time source with the lowest variation.

4 more elements

A non-transitory computer-readable storage medium having instructions stored thereon, which, when executed by a processor, cause the processor to perform a method for determining a best available time source, the method comprising:

receiving, at a time distribution device, periodic time signals from each of a first external time source and a second external time source;
determining, for the first external time source, a first variation of duration between the periodic time signals from the first external time source, the first variation in duration based on a local oscillator;
determining, for the second external time source, a second variation of duration between the periodic time signals from the second external time source, the second variation in duration based on the local oscillator;
comparing the first variation and the second variation;
selecting a best available time source as one of the first time source and the second time source with the lowest variation;
and distributing the best available time source to one or more consuming devices.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 15/349,526Filed 11 Nov 2016 · continuation
Priority: 19 Oct 2012
Published: US 2017/0063482 A12 Mar 2017
Granted: 6 Nov 2018
Term ends: Not estimatedThe source records don’t support an estimate.

Classification12 codes

H04J 3/0688
Clock or time synchronisation in a node; Intranode synchronisation: change of the master or reference, e.g. take-over or failure of the master
G06F 1/14
Generating or distributing clock signals or signals derived directly therefrom: time supervision arrangements, e.g. real time clock
H03K 3/01
Circuits for generating electric pulses; Monostable, bistable or multistable circuits: details
H04J 3/0644
Clock or time synchronisation among nodes; Internode synchronisation: external master-clock

Family

Application61/716,310Us provisional application · filed 19 Oct 2012
Application14/057,803Parent of this continuation · filed 18 Oct 2013
US 2017/0063482 A1Pre-grant publication · published 2 Mar 2017
US 9,520,860 B2Parent of this continuation
US 2014/0111249 A1Published application
US 10,122,487 B2This patent

From the US filing history. Foreign family members aren’t listed.

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