Devices carry timing and synchronization over packet-switched networks -

Devices carry timing and synchronization over packet-switched networks


A family of timing-over-packet (ToP) devices are designed to transmit timing and synchronization over asynchronous packet switched networks. Deploying Zarlink Semiconductor's ZL30301 and ZL30302 ToP devices, network operators can ensure a high quality of service for time-sensitive applications while benefiting from the cost reductions offered by a packet switched network.

The company's Zarlink’s ToP technology is currently being designed into applications including xPON (passive optical networks), broadband-DLC (digital loop carriers), and wireless infrastructure equipment. Wireless service providers can save operating-cost revenue by moving to a packet backhaul infrastructure.

For wireless infrastructure applications, the ZL30302 chip acts as the master and distributes the PRS from the RNC (radio network controller) to the Node B over an Ethernet network. At the Node B, the ZL30301 device acts as the client, extracting timing from the packet network and creating an output clock traceable to the PRS. Redundancy is also achieved, with the ZL30301 chip recovering up to four separate PRS clocks and selecting one for use within the client node.

Both ToP devices support differential clock recovery, a mechanism used when the same PRS is available at both the master and client nodes, for example through a SONET infrastructure. The devices also support adaptive clock recovery, which is commonly used at the edge of the network where a PRS is usually available only at the master node. The two devices maintain an average frequency accuracy of less than +/-15 parts/billion with a Stratum 3 quality temperature controlled crystal oscillator (TCXO). For more information, visit

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