Transmission system with improved synchronization
DCFirst Claim
1. A data transmission system comprising a first node for transmitting packets in a synchronous frame to a second node, wherein the second node comprises a timing extractor to extract a timing signal from the data when a predetermined symbol in a packet is received in a predetermined position in the frame.
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Abstract
In an ATM over STM transmission system, comprising a transmitter and a receiver, a local clock in the receiver has to be synchronized to a clock in the transmitter. To achieve said synchronization, the receiver comprises timing signal extraction means which generates a timing signal each time a first byte of an ATM cell is received in a first byte of an STM frame. Due to the periodically occurrence of the timing signal this is very suitable for synchronizing a local clock. In an advantageous embodiment of the invention, a timing reference value is transmitted by the transmitter to the receiver. This timing reference signal is temporarily stored in a buffer in the receiver. At the instant the timing signal is present at the output of the timing extraction means the content of the buffer is loaded into the clock counter.
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12 Claims
- 1. A data transmission system comprising a first node for transmitting packets in a synchronous frame to a second node, wherein the second node comprises a timing extractor to extract a timing signal from the data when a predetermined symbol in a packet is received in a predetermined position in the frame.
- 7. A node in a data transmission system for receiving packets in a synchronous frame, comprising a timing signal extractor arranged to extract a timing signal from the data when a predetermined symbol in a packet is received in a predetermined position in the frame.
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11. A method for synchronizing at least two nodes in a data transmission system, said data transmission facilitating the transmission of packets in a synchronous frame from a first node to a second node, comprising:
extracting timing information when a predetermined symbol in a packet is transmitted from the first node in a predetermined position in the frame; and
transmitting said timing information to the second node.- View Dependent Claims (12)
Specification