Xref: utzoo sci.electronics:10700 comp.graphics:10472 rec.video:11187 comp.std.internat:631 Path: utzoo!attcan!uunet!tut.cis.ohio-state.edu!pt.cs.cmu.edu!andrew.cmu.edu!ms6b+ From: ms6b+@andrew.cmu.edu (Marvin Sirbu) Newsgroups: sci.electronics,comp.graphics,rec.video,comp.std.internat Subject: Re: "Compatible" HDTV Message-ID: Date: 19 Mar 90 14:55:04 GMT References: <8Zx8Ip200ioEMMrHEF@andrew.cmu.edu> <132618@sun.Eng.Sun.COM> <377@mplex.UUCP>, <1990Mar18.104908.3180@spectre.ccsf.caltech.edu> Organization: Engineering and Public Policy, Carnegie Mellon, Pittsburgh, PA Lines: 27 In-Reply-To: <1990Mar18.104908.3180@spectre.ccsf.caltech.edu> > >I hope the "clean break" approach wins out too. What a engineer's nightmare > >it would be to match up the side panels to the NTSC center. > I heard that the FCC said they wouldn't approve the standard unless its > backwards compatible...=-( The FCC has said broadcasters may have no more than an additional 6 MHz (not necessarily contiguous with their existing frequency allocation. They can use the allocation either to: 1. transmit the "additional" resolution and picture size to be added to the NTSC signal on their existing 6 MHz allocation. 2. transmit an _entire_ HDTV picture. Old sets will be serviced by continuing to broadcast the same programming using an NTSC signal on the original spectrum allocation. While at first glance it would seem easier to send HDTV using the full 12 MHz from both allocations (alternative 1), the problems of combining the two signals-- and living with the defects of existing NTSC-- are such that most technical proposals are along the lines of option 2. Option 2 has the additional virtue that after a few decades when no one has NTSC sets any more, the stations can stop broadcasting in NTSC altogether, and reuse the spectrum for some other purpose (more HDTV programs, land mobile radio, etc.)