Optical time domain reflectometer (OTDR) is an instrument that utilizes optical fiber backscattered and Fresnel reflection to detect fiber attenuation characteristics. With the development of 5G optical communication, the effective maintenance and fault detection of long-distance optical fiber links using OTDR technology have become a research hotspot. This paper proposes a method to enhance the dynamic range by combining Simplex coding and complementary correlated Prometheus orthonormal sequence (CCPONS) coding, thereby extending the fiber detection range beyond that achievable with a single coding scheme.