Clock synchronization over a packet network using SRTS without a common network clock
AssigneeZarlink Semiconductor Inc.
InventorGord Reesor
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Abstract
A method for recovering a service clock through a packet network for the provision of isochronous services uses a two-layer arrangement wherein stable oscillators are provided at the transmitting and receiving nodes. ACR is used to tune the local oscillators over a long period of time. SRTS is used to transfer the service clock except the timestamp information is based on the local oscillators at the transmitting and receiving nodes instead of the common network clock.
Claims11
A method for recovering a service clock through a packet network for the provision of isochronous services, comprising:
- providing first and second stable local oscillators at respective transmitting and receiving nodes;
- generating first timing information for said first stable local oscillator;
- transferring first said timing information between said transmitting and receiving nodes over the packet network based on long-term averaging of the frequency difference between said first and second stable local oscillators;
- using said first timing information to control the second stable local oscillator;
- generating second timing information relating said service clock to said first stable local oscillator;
- and
- recovering said service clock at the receiving node from said second timing information and said second stable local oscillator.
A clock recovery system for isochronous services in a packet network, comprising:
- first and second stable local oscillators at respective transmitting and receiving nodes;
- a first timing transfer layer for synchronizing said first and second local oscillators based on long-term averaging of the frequency difference between said first and second stable local oscillators;
- and
- a second timing transfer layer for transferring timing information between said transmitting and receiving nodes by sending timing information relating a service clock at the transmitting node to the first stable local oscillator and recovering said service clock at the receiving node from said timing information and said second stable oscillator without the use of a common network clock.
Dependencies are inferred from the claim text.