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Session B10: Novel Clock Technologies and Timing Applications 2

Clock Ensemble Synchronization Array Receiver (CESAR) for Open Time Servers
Wil Myrick, ENSCO Inc.
Location: Ballroom E
Date/Time: Wednesday, Jun. 4, 2:10 p.m.

CESAR (Clock Ensemble Synchronization Array Receiver) is a timing receiver fusion architecture integrated into Open Time Server Technology, Commercial-off-the-shelf (COTS) 4G/5G/Wi-Fi MIMO antennas, and Internet of Things (IoT) Technology to provide detection, protection, and location of threats against timing signals. This presentation demonstrates how CESAR fuses an array of clock sources to create a clock ensemble at the edge. CESAR combines 1) 4G/5G/Wi-Fi MIMO antenna technology, 2) GNSS receivers, and 3) clock ensemble fusion algorithms to provide a resilient timing source for the Open Time Server. The critical infrastructure version of the CESAR system is implemented with Open Time Server Technology inspired by the Open Compute Project Time Appliances Project (OCP-TAP) community. This presentation discusses the Internet-of-Things (IoT) version of the CESAR system targeting low SWAP-C mobile platforms. The IoT based CESAR system was recently used in a Positioning, Navigation, and Timing Exercise (PNTAX) 2024 event to understand how the IoT version of CESAR performs in a threat environment. This data is currently being processed to quantify the detection, protection, and location capabilities of an IoT based version of CESAR. This presentation provides initial results of the CESAR timing architecture fusing 1-PPS timing signals. CESAR exploits the spatial diversity of the COTS MIMO array to determine the best combination of clock sources forming the clock ensemble that generates the “paper clock”. The “paper clock” can steer a stable clock reference to take advantage of the long-term clock stability associated with GNSS. While determining the best combination of clock sources, CESAR provides threat detection capability based on tracking the relative clock error deviation associated with each GNSS receiver of the array. The threat protection capability of CESAR is in how well the clock ensemble rejects possible UTC clock sources that are corrupted due to the threat. This provides a “paper clock” that is more resilient than any individual 1-PPS signal associated with the individual GNSS receivers. The threat location capability of CESAR is based on determining which element (or set of elements) of the array are being impacted (more relative clock error deviation) due to the threat environment. The impacted elements provide a coarse level of direction associated with the threat. Three use cases will be shown in this presentation to illustrate the capability of CESAR. The first case will show how CESAR behaves in a benign environment. The second case will show how CESAR responds in a low threat environment. The third case will show how CESAR responds in a moderate to high threat environment. The CESAR response is based on the relative clock error of the 1-PPS (from each GNSS receiver) with respect to a stable clock source (OCXO in this case) not exposed to the threat environment.

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