Xref: utzoo misc.consumers:26394 sci.electronics:17309 Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!samsung!crackers!m2c!umvlsi!dime!dime.cs.umass.edu!chittamu From: chittamu@pogo.cs.umass.edu (Satish Chittamuru) Newsgroups: misc.consumers,sci.electronics Subject: Re: Cable Competition at Last! Message-ID: Date: 26 Jan 91 20:12:18 GMT References: <620@wybbs.mi.org> <1991Jan25.140848.24260@kodak.kodak.com> <1991Jan25.165057.671@ux1.cso.uiuc.edu> <1991Jan26.013437.25836@ux1.cso.uiuc.edu> Sender: news@dime.cs.umass.edu Followup-To: misc.consumers Distribution: na Organization: University of Massachusetts at Amherst Lines: 49 In-reply-to: tmkk@ux1.cso.uiuc.edu's message of 26 Jan 91 01:34:37 GMT In article <1991Jan26.013437.25836@ux1.cso.uiuc.edu> tmkk@ux1.cso.uiuc.edu (Scott Coleman) writes: > > In article <1991Jan25.165057.671@ux1.cso.uiuc.edu> mas35638@uxa.cso.uiuc.edu (Odin) writes: > >> 480 lines > > > >525 is standard. You're talking about a picture which is not as > >good as normal tv broadcasts. > > > He's talking about 480 HORIZONTAL lines, not vertical lines. This is > considerably BETTER than broadcast (which is ~330 or so). A small correction folks. 525 line *IS* the number of horizontal lines is an NTSC television signal. But the fact is not all the lines are display lines. 480 lines are displayed on the screen and the remaining lines are blanked out while the vertical retrace occurs i.e. while the elctron beam is moving from the bottom right of the screen to top left. Now broadcast TV has a channel size of 6 MHz which is the full channel size of an NTSC signal (part of this is an audio signal band, about 300 KHz for FM transmission. Video is AM transmission). So broadcast TV does indeed have a vertical display resolution of 480 lines. Now cable signals do not have such a wide bandwith. Stuff like capacitive/inductive losses on the coaxial cable cause it to have a vertical display resolution of 330 lines. A normal VCR is even worse. The magnetic tape used in regular VCR cannot record a signal of that large a bandwith. The Video signal has a band of about 2.7-3 MHz on the tape. This translates to about 240 lines of vertical resolution. Now the SuperVHS VCRs, by some method (I don't know the technology used there) increase the recorded bandwith and thus are able to give a resolution that is equal to or better than a Cable signal. So, if the satellite system does have 480 line of display resolution, it is technically superior to your Cable system. > Scott Coleman tmkk@uiuc.edu -- -Satish K. Chittamuru chittamu@cs.umass.edu Software Development Lab. chittamu@umass.bitnet Dept. of Computer & Info. Sciences University of Massachusetts Amherst, MA 01002 === Theory of Objectivity: E=MC++