ASIO Audio Device as timecode source ?

Hi, I want to set up my Nuendo to slave to incoming timecode, but can this be an audio signal coming into my audio interface ?

i.e. can I set up one of my inputs to be used as LTC signal in ?

There is an option in sources, and timecode Source, ASIO Audio Device, but it is greyed out… and I can find no info about this in the manual…

Any ideas ?

It’s a while since I’ve been in this area of work, but you will need something like this

Syncing a DAW to incoming LTC is not straightforward, digital clocks need to be aligned.