Golay Complementary Sequence To Improve The Methods Of Of Otor Measurement Dynamic Range

Despite their wide usage during the past several years, few fundamental changes in the design of practical optical time domain reflectometer(OTDR)have been seen. While the use of higher power lasers and the increasing of parallel averaging times have provided some improvement, the trade off between signal-to noise ratio (which determines dynamic range and measurement time) and response resolution can not be solved. An OTDR using correlation technique may has much better performance than conventional OTDR. The autocorrelation of Golay sequence has low sidelobes, so we can use Golay sequence as probe signal.With autocorrelation the dynamic range of an OTDR can be increased significantly and the required measurement time can be reduced greatly without sacrificing the measurement resolution. This paper presents the theoretical foundation of this method. Only unipolar codes can be transferred in fibers. This paper also tells the way to change bipolar codes to unipolar codes.