Embedded System Design for Network Time Synchronization

Abstract

Abstract. Every computer needs a timer mechanism to keep track of current time and also for various accounting purposes such as calculating the time spent by a process in CPU utilization, disk I/O, and so on, so that the corresponding user can be charged properly. In a distributed system, an application may have processes that concurrently run on multiple nodes of the system. For correct results, several such distributed applications require that the clocks of the nodes are synchronized with each other. Nowadays, time synchronization has been a compulsory thing as distributed processing and network operations are generalized. A network time server obtains, keeps accurate and precise time by synchronizing its local clock to a standard reference time source and distributes time information through a standard time synchronization protocol. This paper describes design issues and implementation of an embedded system for network time synchronization especially based on a clock model. Our system uses GPS (Global Positioning System) as a standard reference time source and offers UTC (Coordinated Universal Time) through the NTP (Network Time Protocol). Implementation results and performance evaluation are also presented.

A Scalable Datalogging System with Serial Interfaces and Integrated GPS Time Stamping

“…For the PPS implementation, we have followed Giometti (2006). A comparable system with respect to timing performance, which uses an integrated GPS receiver, is given by Hwang et al (2004). This system, however, was a custom design based on a printed circuit board with an Advanced Reduced Instruction-Set Computing (RISC) Machine (ARM) microcontrollera feature that requires substantial development time and is not as readily available as a standard product.…”

High-Performance Time Server Core for FPGA System-on-Chip

“…This accuracy is far from the range of 1 µs of typical NTP equipment. Other software implementations based on the ARM architecture can be found in [15,16]. The accuracy reported in [15] is in the range of the expected accuracy of 1 ms typical of software-only NTP servers, even though a voltage controlled temperature compensated crystal oscillator (VCTCCO) is used to improve the accuracy of the local clock.…”

“…Other software implementations based on the ARM architecture can be found in [15,16]. The accuracy reported in [15] is in the range of the expected accuracy of 1 ms typical of software-only NTP servers, even though a voltage controlled temperature compensated crystal oscillator (VCTCCO) is used to improve the accuracy of the local clock. The authors of [16] basically did a port of the standard NTP server software to their ARM-based development platform and did not report any experimental results.…”

“…Software-only embedded implementations are cheaper and easier to develop. Nevertheless, these solutions can only provide limited accuracy (e.g., embedded NTP implementations in [13,14]) report an accuracy in the range of several milliseconds, whereas other approaches based on the advanced RISC machine (ARM) architecture [15,16] are close to 1 ms). Similarly, the software-only PTP system in [17] reports an accuracy from 10 µs to 200 µs, depending on the server load.…”