This series of products belong to new products researched and developed aimed at the increased monitoring points, modified old project and new project with dificulties in the video monitoring system. The frequency reuse and signal superposition technologies are adopted to superposition one or several roules of video signals to the other route of video signal and transmit through the same co-axial video cable. The original co-axial video cable is adopted to realize capacity expansion of monitor. It saves the construction wires and reduces construction difficultiesit is the priority choice in the modification of old project.