Algorithms for frame alignment ¿ some comparisons

The paper presents a comprehensive analysis of frame alignment strategies for time division multiplexed digital signals. Comparisons are made between algorthims recommended by CCITT and others requiring slightly more sophisticated terminal processing. The principal transition times (misalignment detection, false exit, acquisition and false entry times) form the basis for comparison. The enhanced algorithms are shown to be better able to handle the conflicting requirements of rapid misalignment detection and the need to maintain an aligned condition in the presence of transmission errors. They also result in a significant reduction in acquisition time at high error probabilities, the condition under which alignment equipment is often required to act.