The HSM series routing switchers are multi-format switchers which enable flexible system integration in the transition period to DTV with HD and SD coexisting. The I/O signal is based on HD-SDI, but SD-SDI can be handled under the through mode (without re-clocking). The HSM-series switchers can accept HD only, SD only, and HD/SD simultaneous application. Since internal signals are handled with serial digital signal, almost no distortion is generated in the routing switcher. Each input module and output module has 16 connectors in one unit. By changing the number of modules, increasing/decreasing the number of inputs/outputs is possible.