I think that the video sync and voltage sensors only work in connection with the IRF-6 System Interface Module. These items could be used to sense the on/off status of a component such as a VCR. Since most VCR have the same on/off IR command, it is easy for a macro function that is meant to turn the system and a VCR ON to actually turn the VCR OFF. The sensors could monitor this status and only allow the IFR-6 to issue the ON command if the VCR was actually off.