A High-Precision Time Synchronization Algorithm Based on Selective Software Switch

In this paper, we present a selective time synchronization algorithm (STSA) based-on two selective switches using a hardware timestamp at a low-level layer to reduce time synchronization errors over Ethernet, and give the improved formula to calculate the time offset when considering the frequency offset factor in SNTP. The STSA transmits frame-based time synchronization frame on a truncated constant back-off collision resolution algorithm to reduce the delay jitter. This means the time accessing a shared Ethernet bus is more predictable. Experiment results indicate that the STSA achieves microsecond-level synchronization and a high synchronization success rate.