Rather than potentially 1000 HN readers each spending 15 minutes on Google trying to work out what you are talking about, may I suggest that you expand that with a few plain English sentences that tell us what that means?
I have no idea what "ATSC" means, and I've been in tech for nearly 40 years now so I have a fairly good handle on this stuff.
Advanced Television Systems Committee. It's the US standards organization for terrestrial digital television. ATSC 3.0 is a new standard that's very similar to DVB-T2 (used in the UK for HDTV) at the PHY layer.
Looks like "PHY layer" means physical layer.