Software Simulation of Oscillator Behaviors in Precision Time Protocol Synchronization
Date Issued
2011
Date
2011
Author(s)
Hsu, Po-Hao
Abstract
Time synchronization is widely used in many applications, such as precise measurement and control, industrial automation, communication systems, air traffic control and commercial systems. IEEE 1588 standard defined Precision Time Protocol (PTP), which is designed for each node in a local network to synchronize their clocks to sub-microsecond accuracy.
The clock servo is the core of PTP time synchronization, usually a PI controller. It uses the time offset between the master clock and the slave clock as the feedback signal to compute the clock tick rate adjustment, and then adjust the output frequency of the slave clock to synchronize the master clock and the slave clock.
Because of the long transient time of the PI controller, we used the Precision Time Protocol daemon (PTPd) and designed the controller. Using the concept of switching controller, we proposed modified PI controller. Before the synchronization reaches the steady state, modified PI controller uses recursive filter to estimate the time drift of the master clock and the slave clock, so that when the synchronization reaches the steady state, the PI controller will converge quickly to reduce the synchronization transient time. In addition, due to the process of time synchronization is very time-wasting, we used software to create the clock signals, including clock noises, to simulate the process of time synchronization, and then used Allan deviation to analyze the steady state stability. The characteristics of the simulated clock signal are in line with the characteristics of the hardware clock, such as the synchronization transient time and the steady state stability.
Subjects
time synchronization
Precision Time Protocol
switching controller
recursive filter
clock noises
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-100-R98921005-1.pdf
Size
23.32 KB
Format
Adobe PDF
Checksum
(MD5):2210ca369c5882921b3c24366ebb08d9