System and method for clock synchronization over packet-switched networks
US7551647B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 19, 2005 |
| Grant date | Jun 23, 2009 |
| Priority date | — |
| Expiry date | Jun 18, 2027 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04J3/0632
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
Embodiments of the invention enable the synchronization of clocks across packet switched networks, such as the Internet, sufficient to drive a jitter buffer and other quality-of-service related buffering. Packet time stamps referenced to a local clock create a phase offset signal. A shortest-delay offset generator uses a moving-window filter to select the samples of the phase offset signal having the shortest network propagation delay within the window. This shortest network propagation delay filter minimizes the effect of network jitter under the assumption that queuing delays account for most of the network jitter. The addition of this filtered phase offset signal to a free-running local clock creates a time reference that is synchronized to the remote clock at the source thus allowing for the transport of audio, video, and other time-sensitive real-time signals with minimal latency.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.