Abstract:This paper describes the principles of Unique Word(UW) detection and the design methods for a UW-detector at lower SNR. An engineering solution for a general purpose UW-detector based on maximum likelihood criteria is proposed. The simulation results show a 3-4dB improvement over the often employed hard-decision/threshold detection when the length of UW is 16 and the SNR is low. The developed UW-detectors have been used in auther s recent communication systems.