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National Positioning, Navigation, and Timing (PNT) Architecture

Should-Be PNT Architecture Graphic


The National PNT Architecture identifies recommendations to be implemented to overcome PNT capability gaps, predominantly resulting from the limitations of GPS. There are increasing occurrences of unintentional and intentional interference to GPS, including the potential for spoofing of the signal. DOT works closely with the Departments of Homeland Security and Defense to increase awareness of vulnerabilities of GPS, to evaluate the impacts, and to research complementary sources of PNT to increase resiliency for safety-critical transportation applications. DOT also coordinates research on new technologies to address emerging PNT needs for applications, such as autonomous vehicles, across all modes of transportation. The objective, in accordance with the effort's Terms of Reference, is to "provide more effective and efficient PNT capabilities and an evolutionary path for government-provided systems and services."

The National PNT Architecture Team identified the following gaps as being of primary concern:

  • Assured and real-time PNT in physically impeded environments
  • Assured and real-time PNT in electromagnetically impeded environments, to include operations during spoofing, jamming and unintentional interference
  • Higher accuracy with integrity needed (especially for future highway and rail applications).
  • Timely notification (as short as one (1) second in some situations) when PNT information is degraded or misleading, especially for safety-of-life applications or to avoid collateral damage
  • High-altitude/space position and orientation, to include real-time high accuracy position and orientation (<10 milliarcseconds) information
  • User access to timely geospatial information for successful navigation
  • PNT modeling capabilities in impeded conditions to determine impacts, more timely modeling capabilities, and a capability to predict impacts in urban environments

The National PNT Architecture development effort identified nineteen recommendations that were approved by the co-sponsors in June 2008. These can be found in more detail in the PNT Architecture Final Report or its associated Executive Summary.

In July 2010 the National PNT Architecture Implementation Plan was approved. The Implementation Plan is an interagency action plan consisting of transition elements that address the PNT Architecture strategy and vectors. PNT Architecture transition elements are the necessary, near-term, and executable tasks that must be implemented by interagency partners to transition the "As-Is" Architecture to a developing and more capable "Should Be" Architecture. Reports pertaining to the National PNT Architecture are included further down on this page.

National PNT Architecture Recommendation Tree

Greater Common Denominator Strategy

  1. Maintain GPS as a cornerstone of the National PNT Architecture
  2. Monitor PNT signals to verify service levels, observe environmental effects, detect anomalies, and identify signal interference for near real-time dissemination
  3. As GPS modernization or other methods demonstrate new operational capabilities, agencies should transition or divest US GNSS augmentation assets that are unnecessarily redundant to their requirements
  4. Continue to investigate methods to provide high-accuracy-with-integrity solutions for safety-of-life applications
  5. Develop a National approach to protect the military PNT advantage

Multiple Phenomenology Vector

  1. Encourage appropriate development and employment of equipment that integrates information from diverse sources and information paths
  2. Assess the potential for the use of foreign PNT systems for safety-of-life applications and critical infrastructure users and, as appropriate, develop clear standards and criteria for their use
  3. Continue military PNT Exclusive Use Policy while studying development of capabilities to enable military use of other signals
  4. Promote standards for PNT pseudolites and beacons to facilitate interchangeability and avoid interference
  5. Study evolution of space-based and terrestrial PNT capabilities to support diversity in PNT sources and information paths
  6. Ensure critical infrastructure precise time and time interval users have access to and take advantage of multiple available sources

Interchangeable Solutions Vector

  1. Use participation in international PNT-related activities to promote the interchangeability of PNT sources while assuring compatibility
  2. Evolve standards, calibration techniques, and reference frames to support future accuracy and integrity needs
  3. Identify and develop common standards that meet users' needs for PNT information exchange, assurance, and protection
  4. Establish common standards that meet users' needs for the depiction of position information for local and regional operations

Synergy of PNT and Communications Vector

  1. Identify and evaluate methods, standards, and potential capabilities for fusion of PNT with communications

Cooperation Organizational Structure Vector

  1. Develop a National PNT coordination process
  2. Identify and leverage Centers of Excellence for PNT phenomenology and applications
  3. Define, develop, sustain, and manage a PNT modeling and simulation core analytical framework

National Positioning, Navigation, and Timing (PNT) Architecture Related Documents