Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site unccvax.UUCP Path: utzoo!watmath!clyde!burl!ulysses!allegra!bellcore!decvax!mcnc!unccvax!dsi From: dsi@unccvax.UUCP (Dataspan Inc) Newsgroups: net.video,net.analog Subject: Re: Q-channel bandwidth Message-ID: <150@unccvax.UUCP> Date: Wed, 6-Mar-85 11:47:17 EST Article-I.D.: unccvax.150 Posted: Wed Mar 6 11:47:17 1985 Date-Received: Sat, 9-Mar-85 10:44:10 EST References: <146@unccvax.UUCP>, <304@petrus.UUCP> Organization: UNC-Charlotte Lines: 20 Xref: watmath net.video:1039 net.analog:190 a Shortly after my inane question, the reason for the narrow Q-bandwidth was privately made known. As the I-channel is vestigial sideband suppressed carrier AM, the frequency components from 500 kc to 1.5 mc will appear in phase quadrature (all together now!) in the Q channel. The choppage of one of the sidebands causes phase modulation of the other..... Oh well. Now, on the other hand, three RCA engineers described an adaptation of NTSC that was fully compatible in the sense that their system could also receive NTSC broadcasts. Both I and Q channels were extended to 1.8 mc bandwidth and cancellation of the sound subcarrier (ala pilot cancellation in modern FM receivers) was used. They didn't (dare ?) mention what the picture looked like on a standard receiver although I suspect the narrow-chroma receiver wouldn't even care in the least. It's in 1970-73 IEEE Transactions on Broadcast Receivers (or something like that). Back to my sickly-green lettuce commercials dya .