![]() ![]() However, the HDMI protocol requires some other digital data transmission, like information about the sender & receiver, that is passed through a non-isolated single ended 5V data interface in the "DDC" cable. Incidentally, the actual video transmission in the "TMDS" cable WAS isolated it passed through one of the cat5 cables without causing hum. Sometimes ethernet cables are used as simple DC connections. Unfortunately, as I learned the hard way, the extender that I purchased fed DC ground and 5V signals through some of the wires of the "DDC" ethernet cable, so there was still a direct ground-ground path through the extender. The isolation was supposed to be achieved by running the HDMI through a HDMI-dual cat5-HDMI extender, which I figure used the balanced twisted pairs in the ethernet cables, so would not need a direct ground connection. I had already determined that the hum & buzz disappeared when the HDMI cable was unplugged, so the shields and grounds of the HDMI cable were definitely the path for the ground noise fed in from the satellite cable shield (noise also disappeared when the sat cable was unplugged). I thought that I could break the ground loop between my DirecTV box and my AVR by using an opto TOSlink cable for sound, and an "isolated" HDMI for video. ![]() Longer explanation of the HDMI issue below. My only recourse was transformer (jensen iso-max), which worked great, but was $$. Short explanation: HDMI extenders do not provide ground isolation. HDMI cat5 extender won't break ground loop ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |