Abstract: A NRZ/CMI (II) code converter comprising a D-type flip-flop for retiming a series of NRZ data bits received thereto with a clock synchronized therewith, an OR-gate connected to said one output of the D-type flip-flop to compose space bits of a series of said received NRZ data bits and a transmitted clock, and a delay element connected to the output of said OR-gate. The converter also comprises another OR gate connected to a negative output of said D-type flip-flop and another D-type flip-flop having a clock input connected to the output of said OR-gate. These elements function to compose mark bits of a series of the NRZ data bits with clock pulses and to generate two-divided alternative mark bits.An exclusive OR-gate is connected to the output of said another OR-gate and the output of said another D-type flip-flop.

Abstract: A reframe circuit in a synchronous multiplexing device comprising a frame synchronizing pattern detection circuit, a frame pattern bit error detection circuit responsive to a serial data stream from the frame synchronizing pattern detection circuit, an in-frame/out-of-frame state discrimination circuit responsive to the output signal from the frame pattern bit error detection circuit and the output signal from the synchronizing pattern detection circuit, a counter phase synchronizing circuit responsive to the output signal from the in-frame/out-of-frame state discrimination circuit, the output signal from the frame synchronization pattern detection circuit and a reference phase signal, and a counter and timing generation circuit responsive to the operating mode control signal from the counter phase synchronizing circuit.

Abstract: The invention provides a receiving counter phase synchronization circuit of the synchronous transmission system, the circuit comprising first line transmitting the signals of logic status according to whether or not synchronization pattern is detected in the serial bit stream; second line transmitting the pre-existence phase information of the receiving counter; a D flip-flop circuit for outputting the delayed data under the control of a clock signal; first NOR logic device connected to the output line of said D flip-flop circuit and said second line; second NOR logic device connected to said first NOR logic and said first line, and having its output line connected to said the data input node of said D flip-flop circuit; an inverter connected to said first line; and an OR logic device connected to the output line of said inverter and that of said first NOR logic device.