Well, we know believe we know what happened... and found a workaround...
It seems the XHD-3903 cards don't pass all DID/SDID combinations in the VANC data. They do pass the ones for ABC's answer to the Namedropper, but not the ones for the NBC unit.
- So why did it work for a year?
When the HD Namedropper was first deployed, they didn't have a way of triggering it over the HD network. Affiliates had to pass a copy of the SD signal to an "auxiliary in" jack on the unit. It would find the trigger signals here.
This summer, after analog broadcasting ceased, we disconnected the SD feeds to Comcast and the satellite services from the SD side of the MCR switcher, and hooked them through a 500DCDA downconverter (and the 2.0 downmix output of the Linear Acoustic) to the HD side.
But we never "unslaved" the SD and HD sides, nor did we disconnect the SD feed from the Namedropper.
So it was still triggering from the SD network.
- So why did it stop working last weekend?
The IRD got confused in a way that caused the Namedropper VANC data to be blocked. (NBC says that's happened before, and we had vague reports of network audio popping on Saturday) The first thing we did when we got in on Monday was to check the NBC documents and note the Namedropper was supposed to be set to trigger from Video In, not Auto. *Then*, when that didn't help, we rebooted the IRD.
Chances are, there were no trigger signals until we rebooted the IRD. By the time the IRD came back up, the Namedropper was no longer looking at the SD network -- and there were no trigger signals on the HD input.
So sure enough, switch it back to look at the Aux In -- and it's working.
Not that that's much of a long-term solution. Harris now has the DID/SDIDs for NBC and we expect them to have a firmware upgrade shortly.....
Doug Smith W9WI
Pleasant View, TN EM66