Adapter for the connection to a clear-channel telecommunication network

Abstract

An adapter having a line interface circuit for providing an analog attachment to a network (100). The line interface circuit is provided with a reset input for beginning a resynchronization of the timing of the adapter. The adapter further includes a Digital Phase-locked Loop device DPLL (203) driven by a master clock (306) which provides the timing and synchronization signals to the line interface circuits (201). The DPLL (203) divides a master clock down to an internal INT clock (309), a phase comparator (303) compares the INT clock with a reference signal (302) which is synchronized with the receive clock (202) extracted from the line by line interface (201). The phase comparison process operates with a Correction Signal (CS) which has a window centered around the falling edge of the INT clock. A frequency correction is initiated when the reference clock falls outside of the correction window and is achieved by inserting or suppressing a master clock pulse at this time. The adapter further includes means for resetting the line interface circuits and the DPLL at the power-on of the adapter, such that the frequency correction apparatus of the adapter causes two adapters attached at separate ends of a transmission medium to evolve toward stable timing states with respect to each other.