Resilient PNT Services for Transportation Infrastructure

Protecting and securing GNSS reception begins with the ability to determine the quality of the live-sky GNSS signal. This visibility is best achieved by monitoring key GNSS observables which are used to calculate position, navigation and time. Examples of GNSS observables include tracked satellite count, RF power level, carrier-to-noise ratio and phase-time-deviation measurements. Just as a network firewall detects and protects against network attacks, a GNSS firewall delivers visibility of jamming and spoofing threats to alert transportation operations of untrusted sky-based signals.

CI transportation operators not only depend on position and navigation services delivered by GNSS, they also rely on timing services from GNSS for their secure and private network communications. These networks deliver critical voice communications and telemetry data throughout airport facilities, to train stations and rail yards and to shipmasters and port administration authorities. Networks must be built to support high-speed transport of data and high-reliability wireless communications. This must be achieved with extremely low levels of network latency and the ability to time stamp events at dispersed locations. All these requirements depend on timing services from GNSS.

To support secure and private network communications, the Virtual Primary Reference Time Clock (vPRTC) is a highly secure and resilient network-based timing architecture that blends our secure GNSS firewall technology, high-precision atomic system clocks and a portfolio of trusted time solutions to meet the expanding needs of modern critical infrastructures such as those required by CI transportation. 

The combination of GNSS visibility and the vPRTC architecture provides CI transportation operators with a dual-purpose solution for the use of PNT services as delivered by GNSS. It provides situational awareness about the health of GNSS reception by monitoring and evaluating key GNSS observables in real time to determine if there is risk in the use of PNT delivered by GNSS. It also offers a layer of protection that enables a more responsible use of PNT services, including greater resiliency if live-sky delivery of PNT by GNSS is disrupted, degraded, or worse, becomes unavailable. Like a network firewall, this solution creates a dome of protection that strengthens the overall use of PNT services by GNSS for CI transportation infrastructure.