Method for detecting transmitting control code using M our of N detection scheme for initiating a latching loopback test procedure

摘要

In a data port for a digital data system in which latching loopback is implemented, a unique and efficient algorithm is utilized to achieve M out of N control byte recognition. In the algorithm, N-M+1 variable length windows are used to count identified control bytes. The algorithm opens a window when the desired byte has been detected, counts the identified bytes while the window is open, and closes the window when a non-target byte is detected. The counts in the various windows are summed to determine if M bytes have been detected. A window having the oldest byte count is effectively dropped so that the window is available to count newly-arriving target bytes.