Evaluation of timestamping uncertainty in a software-based IEEE1588 implementation

The IEEE1588 became in the last years the de-facto solution to obtain a strict synchronization over a local area network. The purpose of the paper is to analyze the uncertainty sources that affect a software-only implementation of the IEEE1588 (the so called PTPd) based on off-the-shelf PC components. A careful analysis of timestamp mechanism and time management in a PC platform with an Operating System is carried out. The experimental setup presented in the paper highlights that the main uncertainty source of a software-only synchronization approach is the timestamp method. At the end of the paper, an index to evaluate the Timestamping uncertainty, called Timestamping Uncertainty Index (TUI) has been proposed and applied to the test case presented.

[1]  David L. Mills,et al.  Network Time Protocol (Version 3) Specification, Implementation and Analysis , 1992, RFC.

[2]  A. Bondavalli,et al.  Improving robustness of the synchronization quality of IEEE1588 nodes , 2010, 2010 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control and Communication.

[3]  A. Flammini,et al.  Testing coexistence of different RTE protocols in the same network , 2008, 2008 IEEE International Workshop on Factory Communication Systems.

[4]  D. Niehaus.  Hrtimers and Beyond : Transforming the Linux Time Subsystems , 2009 .

[5]  G. Gaderer,et al.  Limits of synchronization accuracy using hardware support in IEEE 1588 , 2008, 2008 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control and Communication.

[6]  Yuriy S. Shmaliy,et al.  Optimal Synchronization of Local Clocks by GPS 1PPS Signals Using Predictive FIR Filters , 2009, IEEE Transactions on Instrumentation and Measurement.

[7]  G. Gaderer,et al.  Master failures in the Precision Time Protocol , 2008, 2008 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control and Communication.

[8]  Robert Love,et al.  Linux Kernel Development (2nd Edition) (Novell Press) , 2005 .

[9]  Claudio Narduzzi,et al.  Performance analysis of Kalman filter-based clock synchronization in IEEE 1588 networks , 2009, 2009 International Symposium on Precision Clock Synchronization for Measurement, Control and Communication.

[10]  Ilija Hadzic,et al.  Adaptive packet selection for clock recovery , 2010, 2010 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control and Communication.

[11]  M. Branicky,et al.  Design Considerations for Software Only Implementations of the IEEE 1588 Precision Time Protocol , 2005 .

[12]  Daniel Pierre Bovet,et al.  Understanding the Linux Kernel , 2000 .

[13]  Andrea Bondavalli,et al.  Safe estimation of time uncertainty of local clocks , 2009, 2009 International Symposium on Precision Clock Synchronization for Measurement, Control and Communication.

[14]  David L. Mills,et al.  Network Time Protocol (Version 3) Specification, Implementation , 1992 .

[15]  Robert Love,et al.  Linux Kernel Development , 2003 .

[16]  Kang Lee,et al.  IEEE 1588 standard for a precision clock synchronization protocol for networked measurement and control systems , 2002, 2nd ISA/IEEE Sensors for Industry Conference,.