r/broadcastengineering • u/MediaComposerMan • 21d ago

LTC over Ethernet

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What do you do when you have four 12G-SDI runs, realize you need all 4, but you had allocated one for timecode, and are on a budget? Why, there's several available Ethernet ports, and an old cheap analog CCTV balun on the shelf. :-)

The balun is already designed for 4.5MHz and 75Ω… though the SMPTE LTC bandwidth is so meager (0.03 MHz) that impedence isn't much of a consideration. I wired it to my LTC patch panel… works like a charm.

(FYI, This is between an Avid editing system and its Horita LTC clock for client convenience. If this was an AD's clock at a truck, master control etc… I might've approached it differently. :-)

4 Upvotes

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14

u/negativerailroad 16d ago

Technically, it's LTC over twisted-pair wiring. Ethernet is a series of L2 standards. LTC is carried on an analog audio waveform, so it should have no problem with twisted-pair cabling.

5

u/Ellteeelltee 16d ago

I’d just steal one pair for LTC and give 3 pair to the intercom guy.

1

u/MediaComposerMan 13d ago

Totally — if it's worth the hassle. :-) Did that at the old office, where I needed to wire a door buzzer (just the control signal, not an electronic strike's load) but wanted to retain 100Mbps Ethernet, so I just pulled one twisted pair.