The UFM-80SDICS is a modular-type SDI changeover switcher that can be mounted in a UFM frame. Seamless automatic switching of 3G/HD/SD-SDI signals increases duplex transmission reliability. This SDI seamless switcher duplicates the uncompressed SDI signal over a fiber-optic line and monitors the SDI signals of 2 systems decoded after duplex transmission, and switches seamlessly to the other line when signal loss, video freeze, audio mute or other errors are detected.