About CAST

Alternative Timing is a component of the larger concept Alternative Positioning, Navigation, and Timing, or PNT. PNT is the integration of technologies and methods to allow the precise determination of location, movement, and time for assets within our environment, from cell phones and personal vehicles, to ships and aircraft, to industrial devices that need to operate in synchronized ways. PNT is most closely related to the Global Positioning System (GPS) in the United States, and to Global Navigation Satellite Systems (GNSS) outside of the United States, where these satellites deliver signals to receivers on the ground, which in turn process those signals to determine local position and time.  

GPS and GNSS is most prolific source of time around the globe. These satellites deliver time to people and businesses that, in the US, is synchronized to the US Naval Observatory (USNO) and the National Institute of Standards and Technology (NIST) authoritative time sources. NIST and USNO synchronize to other authoritative time sources international to establish a globally recognizable time reference, Coordinated Universal Time, or UTC. 

While GPS/GNSS is a highly reliable and stable source for PNT for our nation, it also has limitations and vulnerabilities that require mitigation. Given the critical importance of GPS to our infrastructure, it is necessary to develop alternatives that ensure the resilience of our infrastructure in the event of GPS/GNSS disruptions. Alternative PNT, and alternative timing, are rooted in augmented the capabilities of GPS/GNSS to ensure infrastructure resilience in the face of potential disruptions. Alternative timing solutions provide approaches to synchronizing with those authoritative timing sources, and delivering/synchronizing time across a distributed set of assets without utilizing GPS/GNSS.  

Precise time is critical for the operation of many US industries, including communications networks, the financial industry and stock market, and the power grid. Without precise (and secure) timing and an ability to synchronize across a range of disparate locations and devices, these industries would not be able to fulfill their missions for the US economy and our way of life would be significantly altered. 

With regard to the power grid, timing is utilized in everything from high-performance sensors on the grid (i.e., synchrophasors), to command and control centers (supervisory control and data acquisition [SCADA]), to logging and reconstruction of electricity-related events. Each of these requires a different level of accuracy and precision of time synchronization, with some applications requiring as little as 250 nanoseconds of accuracy. 

Alternative timing research at ORNL is investigating solutions for each of these challenge areas for the power grid. CAST is focused on the design, R&D, testing, and validation of timing and synchronization architectures that can broadly support grid applications. This research ensures the US has an understanding of the hardware, software, network, communications, and security capabilities and limitations available on the market today, and the appropriate ways to implement these solutions to ensure a resilient grid for the US. 

ORNL Timing & Synchronization Lab 

ORNL’s Timing & Synchronization Lab is a one-of-a-kind environment to enable the testing and evaluation of timing across a number of use cases. With an emphasis on commercial-off-the-shelf (COTS) technologies, we developed partnerships with dozens of industry partners to improve, refine, and adapt original equipment manufacturer (OEM) capabilities to power utility needs. Our lab, situated at the Grid Research Integration and Deployment Center (GRID-C) on ORNL’s Hardin Valley Campus, boasts a number of optical and magnetic Cesium atomic clocks, rubidium clocks, signal and network emulators, and routers to support delivery of timing signals to devices on the grid, along with active network circuits to multiple utilities in the US over a variety of mediums. 

In addition to the lab, the timing testbed environment extends to ORNL’s main campus and the Distributed Energy Communications and Controls (DECC) laboratory, where we test and integrate precise and secure timing signals with sensors and other grid assets. 

Frequently asked questions coming soon!

Live performance data from CAST terrestrial timing network coming soon!