Local Timestamp-based Adaptive Clock Method for TDM over Ethernet

Clock methods for circuit emulation service over Ethernet are introduced and analyzed. A novel adaptive clock recover method ——Kalman-filter Based Local Time Stamp(KBLTS) method is presented. The method can be thought as a timestamp based adaptive method, but no timestamp needs to be transported over the Ethernet network. With the local service clock, the timestamp information(local timestamp) related to the service clock of the remote end and the near end can be attained by a local counter. By statistics computating , the timestamp information can be transformed into a random data sequence that is appropriate for the Karlman equations. By using Karlman filter algorithm, the noise brought about by Ethernet network can be filtered and the true timestamp can be extracted. With the timestamp, local service clock can be adjusted the same as the far end by a voltage-controlled oscillator. A kind of simulation device is designed and a test platform is set up to test and verify the method.