Standard transmission and recording of high resolution television

Abstract

The full potential of high resolution television by synchronized modulation of the scan lines at the camera and display unit is achieved in standard transmission through band limited channels by: separating out of the video signal from the television camera the modulation frequency as sidebands with pixel information, for example 7.16.+-.1/2 MHz in the case of a color subcarrier at 3.58 MHz under the NTSC standards and pixel information modulated on sidebands in a narrow band (about .+-.1/2 MHz); converting the sidebands with pixel information down to within the color subcarrier band (in the range of 3.75 MHz to 4.2 MHz) using a heterodyne converter; and adding back to the video signal out of the camera the down-converted sidebands with pixel information before processing it through the color encoder for transmission through the bandwidth limited channel. The transmitted signal may be received and displayed by a standard television receiver or monitor, but to achieve the higher resolution which modulation of the scan line affords, the receiver, or monitor, must be modified to convert the color reference frequency to the line scan modulation frequency (synchronized with the color subcarrier) and, while using the color reference at the standard frequency for color decoding, using the modulation frequency to modulate the line scan of the color display tube at the same time the detected video signal is filtered to separate the down-converted sidebands with pixel information, convert the sidebands with pixel information back up to the modulation frequency using a heterodyne converter, and add the up-converted sidebands with pixel information back into the detected video signal for processing in the receiver or monitor modified to modulate the scan lines for display.