The interesting thing, their
joint statement didn't blame DIRECTV or AT&T for the issue, it says it was caused by an issue with the service contact of a 3rd party company, and it's usually on the stations to provide the fiber link if their OTA signal isn't strong enough at their market's local receive facility. DIRECTV's receive facility for the Champaign-Springfield-Decatur DMA is an AT&T exchange building in Decatur and is out of range of
WSEC's signal and in the fringes of
WEIU's signal.
Dish's local receive facility for the DMA is at WCIA's studio in Decatur, but it has a link to WCIX's studio in Springifeld who can probably relay the western signals to them. (n/m, the address on Dish's website is outdated, WCIA/WCIX hasn't been there in years)
If they aren't using direct fiber feeds, the cable providers can just ingest it OTA at whatever headend/hub is in range and distribute it internally, and in many cases the fringe ones don't have DMA wide cable carriage. i.e. in NYC, NJ PBS doesn't have carriage on Optimum's Long Island systems, and WLIW doesn't have carriage on their Hudson Valley and New Jersey systems, and in the Boston DMA, NH PBS and GBH struck an in state only agreement, so New Hampshire cable systems no longer carry WGBH and WGBX and Massachusetts systems no longer carry WENH.
At least for DIRECTV, WSIU, WUSI and WQEC are being ingested seperately as their thumbnail timestamps are out of sync, and WQEC has a completely different station ID and interstitial content, so even though WSIU/WUSI tookover their operations in 2018, the WSEC/WQEC/WMEC trio is still not a 100% simulcast. (DIRECTV doesn't carry WMEC Macomb as it is in the same DMA as WQEC Quincy) If it's like some other multimarket PBS stations, there might also be variations in what EAS warnings/tests each signal passes.