Abstract: A data scrambler circuit which adds the SONET polynomial 1+X.sup.6 +X.sup.7 to data in a parallel format to thereby reduce circuitry clock rates to one-eighth the line rate, which reduces power consumption and simplifies timing constraints. A circuit embodiment includes a first series of flip-flops connected to generate the polynomial and a second series of flip-flops for holding the generated polynomial. To provide a relatively large window of time for looking at the data, parallel data is obtained by providing a parallel-to-parallel register at the output of a serial-to-parallel register. The parallel data is added to the held polynomial by a series of exclusive OR gates.

Abstract: A data scrambler circuit which adds the SONET polynomial 1+X.sup.6 +X.sup.7 to data in a parallel format to thereby reduce circuitry clock rates to one-eighth the line rate, which reduces power consumption and simplifies timing constraints. A circuit embodiment includes a first series of flip-flops connected to generate the polynomial and a second series of flip-flops for holding the generated polynomial. The parallel data is added to the held polynomial by a series of exclusive OR gates.

Abstract: A frame error detection system for SONET which operates in both the OC-3 and OC-12 modes. The frame detection circuit operates by examining the incoming data bit stream, which is in parallel form, detecting A1 and A2 bytes and if, in the OC-3 mode, three consecutive A1 bytes are received, followed by three A2 bytes, then framing is correct. If one of these bytes is missing, then there is an error in framing. The bytes, as they are received and processed by the system, are stored in a series of flip-flops and the output logic signal therefrom is indicative of the framing condition as to whether it is correct or errored.