Zarlink Semiconductor Limited

Geoffrey Edward Floyd

Timothy Michael Edmund Frost

Martin Raymond Scott

James F Kosolowski

Martin Richard Crowle

A method of synchronising first and second clocks coupled respectively to ingress and egress interfacesof a packet network, the method comprising calculating a minimum packet Transit Time over the networkin each of successive time intervals, and varying the frequency of the second clock so as to track variations in the minimum packet Transit Time.

Clock synchronisation over a packet network

A method for distributing timing information across a packet network includes generating timing signals at a master clock at predictable intervals using a clock reference of a given frequency. The timing signals are broadcast or multicast to a plurality of slave clocks over the packet network, preserving the timing signal intervals. At each slave clock, the intervals between successively received timing signals are determined. A clock recovery algorithm is applied to the determined intervals to recover in substantially real time the original clock frequency. The local clock frequency of the slave clock is synchronized to the recovered frequency.

Method and apparatus for distributing timing data across a packet network

A method of updating a lookup table associated with a TDM transmit unit which is coupled to a packet network to receive data therefrom, the lookup table mapping packet network contexts to TDM channels. The method includes priming a controller with data for updating the lookup table in advance of the receipt of packets containing data to which the update relates, incorporating a flag in each packet sent over the packet network to the TDM transmit unit, the flag being set to indicate whether or not a packet is the first packet to which the update relates, and detecting the setting of the flag in a first packet and in response updating the lookup table with the update data.

Signalling TDM channel changes

A method of mapping between contexts of a packet network and TDM channels and streams. The method comprises constructing a lookup table defining the sequence in which data is to be mapped between contexts and TDM channels and streams, and including for each row of the table a flag which indicates whether or not that entry is the first entry in the table for the corresponding context. As the TDM receive or transmit entity cycles through the lookup table, use is made of the flags to synchronize the start of each packet with the first entry of a TDM frame for each context.

Mapping between TDM channels and packets

A method of providing data for transmission on a time division multiplexed (TDM) serial data stream. The method comprises mapping channels of the TDM stream to contexts, each context comprising a set of memory buffers for storing data to be transmitted. Data is extracted from the contexts in a sequence defined by said mapping and transmitting the extracted data on the TDM stream. When a buffer or buffers of a context become empty, a buffer refill request is generated to cause data to be read from a memory to refill the buffer, wherein each buffer refill request is assigned a priority. The context buffers are refilled in an order defined by the respective priorities of the refill requests.

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Yelverton, United Kingdom

Geoffrey Edward Floyd