Abstract:
A method and system are provided for allowing time-alignment of teleprotection measurements of power signals. Teleprotection observations are communicated between teleprotection ends through a packet switched network. At each end of a teleprotection segment, a teleprotection device communicates with the network through a router providing CES and located at the edge of the network. Clocks within the two routers are synchronized using IEEE 1588v2 signals. Using this synchronization, accurate one-way latency of data through the network between the two routers in each direction can be determined. The router at the incoming end of the faster path delays playout of packets by the difference between the two one-way latencies, thereby ensuring time-alignment of observations as they are sent from the routers to the teleprotection devices.
Abstract:
A method and system are provided for improving maintenance of timing information when a node enters holdover due to a lost connection between a sub-network and a reference clock. Each node within the sub-network sends information concerning the drift of its local oscillator to a single node, and the single node uses this information to determine timing information for the entire sub-network. The single node may also use knowledge of the characteristics of the local oscillators. In this way, drift from the reference clock can be minimized without incurring significant added hardware costs.
Abstract:
A method and system are provided for synchronizing local clocks more quickly in a telecommunication network using IEEE 1588. A network element that receives timing signals from one or more possible parent clocks considers a measure of the reliability of the timing signals contained in Announce messages from the parent clock or clocks. The clock uses this reliability information in selecting one of the possible parent clock or clocks to use as the actual parent clock. Once the selection is made, the clock adjusts the filtering characteristics applied to timing signals received from the selected parent clock. The adjustments reflect how confident the parent clock is as to how stable the timing information, it provides has become. If the indication of reliability contained in Announce messages received from the parent clock indicates that the timing information is not very reliable, then a high filter bandwidth is used in filtering the timing signals. If the indication of reliability contained in Announce messages indicates that the timing information is reliable, such as by crossing a threshold, then the clock shifts to a normal low bandwidth filtering. By using reliability information in the Announce messages, clocks can better make selections as to which parent clock to use, and can use the reliability information to more quickly synchronize themselves with a grandmaster clock.
Abstract:
A method and system are provided for synchronizing local clocks more quickly in a telecommunication network using IEEE 1588. A network element that receives timing signals from one or more possible parent clocks considers a measure of the reliability of the timing signals contained in Announce messages from the parent clock or clocks. The clock uses this reliability information in selecting one of the possible parent clock or clocks to use as the actual parent clock. Once the selection is made, the clock adjusts the filtering characteristics applied to timing signals received from the selected parent clock. The adjustments reflect how confident the parent clock is as to how stable the timing information, it provides has become. If the indication of reliability contained in Announce messages received from the parent clock indicates that the timing information is not very reliable, then a high filter bandwidth is used in filtering the timing signals. If the indication of reliability contained in Announce messages indicates that the timing information is reliable, such as by crossing a threshold, then the clock shifts to a normal low bandwidth filtering. By using reliability information in the Announce messages, clocks can better make selections as to which parent clock to use, and can use the reliability information to more quickly synchronize themselves with a grandmaster clock.
Abstract:
A method and system are provided for allowing time-alignment of teleprotection measurements of power signals. Teleprotection observations are communicated between teleprotection ends through a packet switched network. At each end of a teleprotection segment, a teleprotection device communicates with the network through a router providing CES and located at the edge of the network. Clocks within the two routers are synchronized using IEEE 1588v2 signals. Using this synchronization, accurate one-way latency of data through the network between the two routers in each direction can be determined. The router at the incoming end of the faster path delays playout of packets by the difference between the two one-way latencies, thereby ensuring time-alignment of observations as they are sent from the routers to the teleprotection devices.
Abstract:
An intermediate clock, either a boundary or a transparent clock, may have to adjust its local clock to match that of a grandmaster clock. If such adjustment is frequent or large, then the intermediate clock may not have much confidence in the reliability of the timing information it passes to a downstream clock in an IEEE 1588 Announce message even if the quality of its local clock is high. The intermediate clock determines a measure of the reliability of its timing information. The intermediate clock inserts an indication of the reliability of the timing information in a transmitted IEEE 1588 Announce message. The intermediate clock may consider an indication of reliability found in an Announce message it receives when inserting an indication of the reliability of timing information into an Announce message which it transmits.
Abstract:
A method and system are provided for improving maintenance of timing information when a node enters holdover due to a lost connection between a sub-network and a reference clock. Each node within the sub-network sends information concerning the drift of its local oscillator to a single node, and the single node uses this information to determine timing information for the entire sub-network. The single node may also use knowledge of the characteristics of the local oscillators. In this way, drift from the reference clock can be minimized without incurring significant added hardware costs.
Abstract:
An intermediate clock, either a boundary clock or a transparent clock, may have to adjust its local clock to match that of a grandmaster clock. If such adjustment is frequent or large, then the intermediate clock may not have much confidence in the reliability of the timing information it passes to a downstream clock in an IEEE 1588 Announce message even if the quality of its local clock is high. The intermediate clock determines a measure of the reliability of its timing information. The intermediate clock inserts an indication of the reliability of the timing information in a transmitted IEEE 1588 Announce message. The intermediate clock may consider an indication of reliability found in an Announce message it receives when inserting an indication of the reliability of timing information into an Announce message which it transmits.