The microsecond is the most discussed unit in industrial timing systems, because microsecond accuracy is required to support critical infrastructure. Most critical infrastructure timing systems depend upon GPS, simply because microsecond accuracy is easy to achieve with GPS, and difficult to achieve without it. This paper explores how GPS clocks meet the accuracy requirements of two critical-infrastructure applications, mobile telephone networks and the electric power grid. Both industries require time accurate to a microsecond at thousands of geographically dispersed locations, and thus rely upon thousands of GPS clocks. The paper also discusses the vulnerabilities of GPS clocks, and reviews possible backup strategies for maintaining microsecond accuracy across a large geographic region when GPS is unavailable.
Citation: IEEE Instrumentation and Measurement Magazine
Pub Type: Journals
clocks, GPS, synchronization, time, time transfer