This paper describes the decoder of a ternary optical computer’s applied research systems, SD11. Hardware of the decoder includes four cameras, an embedded system, and an adapter plate connecting the cameras with the embedded system. With this adapter plate, works of the four cameras is time-shared controlled by a program in the embedded system. Some modules such as data storage, threshold decision and three alues data generation used in the decoder are contributed by the existing research. Having integrated these into the system, an available core program of the decoder is formed. Since the software is independent of the particular process of picture taking, the core part of the program may be used in the future commercial ternary optical computer. The contribution of this work is to study the ternary optical decoder’s functionality and adaptability to environmental change via a series of test. Through the experiments, the problem of image quality degradation is solved when the signal carrying wire is longer than 1.2 m. This makes the decoder meet the requirements for the SD11’s practical uses, and promotes the development of ternary optical computer.