The SDI router undoes what the cable does to the signal and sends it to where it needs to go. That is, it reconstructs the signal to its original integrity and routes (distributes) the signal to the desired destination (end equipment). At SD and 1.5G HD rates, the signal conditioning need was mainly focused on the long cable interfaces. Now at 3G HD rates, there is much more internal interconnect and loss. Therefore, the design must apply parts with built in signal conditioning where needed to ensure signal quality.