Abstract: An apparatus and method to find CRC protected data packets by updating a cyclic redundancy checks (CRC) sum calculated from a data stream of CRC protected packets by adding new data while subtracting an effect of old data, and checking the updated CRC sum for a predetermined result. The apparatus includes a m-length memory to store a data stream an n-length accumulator to accumulate a CRC sum from the data. The apparatus includes a remainder circuit to feedback the data leaving the accumulator to the accumulator based on a predetermined CRC polynomial and a subtraction circuit to remove the effect of data leaving the memory from the accumulator. A CRC sum validation circuit checks the CRC sum for a valid result to indicate that the data packet protected by the CRC is located.

Abstract: A clock distribution system including a first and second phase detector. The first phase detector outputs a phase lead of an output clock signal. The second phase detector outputs a phase lag of a returned clock signal. Circuitry is included that propagates the output clock signal onto a transmission line based on the average the output of the first phase detector and the second phase detector.