1 channel high quality video analog signal and 4-6 channel bidirectional digital signal are transmitted through optical fiber. Focal 914 is an industrial minimum structure, ultra-small and durable design, which can be applied to a wide range of temperature changes. Two-way transmission is carried out through 1 channel of single-mode or multi-mode optical fiber, which provides 10-bit data link and video of broadcast level greater than 6MHz bandwidth for high-resolution cameras, 4 channels of serial port two-way data channel (2xrs-232,1x high-speed rs-485/422), and LED lights on the board automatically detect the connection status of digital, video and optical fiber.