Systems and methods for synchronizing backup receivers to network clocks

A communication system, comprising:

• a first interworking function (IWF) coupled to a packet network, the first interworking function configured to receive a first time division multiplexed (TDM) data signal and to interwork data from the first TDM data signal into a plurality of data packets, the first IWF configured to transmit the plurality of data packets through the packet network, each of the data packets comprising a respective time value relative to a first clock signal;
• and
• a second interworking function (IWF) coupled to the packet network, the second interworking function configured to receive each of the plurality of data packets and first timing information from the packet network, the second IWF having a first receiver and a backup receiver, the first receiver configured to receive at least one of the data packets prior to a backup switch for switching communication from the first receiver to the backup receiver, the first receiver configured to interwork data from the at least one data packet received by the first receiver into a second TDM data signal and to control a timing of the second TDM data signal based on a second clock signal such that the second TDM data signal is synchronous to the first TDM data signal, the first receiver further configured to control a timing of the second clock signal based on the first timing information such that the second clock signal is synchronous to the first clock signal, the backup receiver configured to receive at least one of the data packets after the backup switch, the backup receiver configured to interwork data from the at least one data packet received by the backup receiver into a third TDM data signal and to control a timing of the third TDM data signal based on a third clock signal such that the third TDM data signal is synchronous to the first TDM data signal, the backup receiver further configured to control a timing of the third clock signal based on second timing information such that the third clock signal is synchronous to the first clock signal, wherein the second timing information is transmitted from the first receiver to the backup receiver prior to the backup switch.

A communication method, comprising the steps of:

• receiving, via a first receiver, first data packets and first timing information from a packet network;
• generating a first clock signal via a first digital oscillator;
• controlling a timing of a first clock signal based on the first timing information and at least one frequency control word such that the first clock signal is synchronous to a second clock signal, the first timing information based on the second clock signal;
• interworking, via the first receiver, data from the first data packets to a first time division multiplexed (TDM) data signal;
• controlling a timing of the first TDM data signal based on the first clock signal;
• switching communication from the first receiver to a backup receiver;
• receiving, via the backup receiver subsequent to the switching step, second data packets and second timing information from the packet network;
• generating a third clock signal via a second digital oscillator;
• controlling a timing of the third clock signal based on the second timing information and the at least one frequency control word such that the third clock signal is synchronous to the second clock signal, the second timing information based on the second clock signal;
• interworking, via the backup receiver, data from the second data packets to a second time division multiplexed (TDM) data signal;
• and
• controlling a timing of the second TDM data signal based on the third clock signal.