Abstract: A frame phase aligner for a transfer system includes selection circuitry for selecting one of a plurality of input signal groups, which include data, a clock signal, an inverse clock signal and a frame synchronous signal, received from outside of the frame phase aligner. A selection signal generator provides the selection circuitry with a selection signal according to write data input from outside of the frame phase aligner, so that the selection circuitry selects one of the plurality of input signal groups according to the selection signal indicative of the setup environment of the transfer system. A control signal generator generates control clock signals and a retiming control signal in order to demultiplex selected data of the input signal group selected. A demultiplexer demultiplexes data selected to form parallel data, retimes the parallel data, and controls the phase of the parallel data according to the control retiming signal and the control clock signals output from the control signal generator.

Abstract: An add-drop control apparatus includes first and second data input units for inputting external first and second data signals, respectively, a frame phase arrangement unit for arranging phases of an external add data signal, an add data controller for transferring a first add data signal from the frame phase arrangement unit to a host stage in a selected one of a plurality of operating modes under control of a processor, a drop data controller for transferring selectively first and second drop data signals from the first and second data input units and a local loop back data signal from the add data controller to a tributary stage in the selected operating mode under the control of the processor, first and second data output controllers for transferring selectively first and second remote loop back data signals from the first and second data input units, first and second through data signals from the second and first data input units and second and third add data signal signals from the add data controller ex