We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
MODULATION FREQUENCY IS EQUAL TO
AEVEN HARMONIC OF \fl [LINE FREQ]
B-ODD HARMONIC OF 1/2 [LINE FREQ.]
LIME 1
LINE 1 PIUS LINE 526 ADO IN PHASE
LINE 1
PLUS
LINE 526
CANCEL
TIME— •*
Fig. 5. Principle of interference cancellation by frequency interleaving.
Courtesy, Electronics (Ref. 9, Fig. 2).
•LINE 3 OR 526
t \ ,' \ I \ /
N..V X..X v..X
the use of that signal as a luminance signal either for color or for monochrome receivers.
Compatibility Considerations
We have seen that the signal for monochrome television and the luminance component of a color-television signal must satisfy the same set of requirements ; we have also seen that idle intervals exist in the transmitted band of this signal in which another signal may be placed, and we shall presently find that the color components of the color-television signal may be placed there; we have also seen that a signal placed in these idle intervals is essentially invisible on a black-and-white receiver. There is no disadvantage then in adopting for the luminance component of a colortelevision transmission identically the same standards which have been found suitable for a high-grade monochrome transmission. And we should bear in mind that the performance capabilities of the black-and-white television signal
represented by the FCC's standards, are likely to equal or exceed any demand for performance to be encountered in the foreseeable future.
But there is more to this than the mere absence of a disadvantage. If our colortelevision signal consists of a luminance component conforming exactly to the present monochrome standards and an interleaved color component which is essentially invisible on monochrome receivers, then our color-television broadcast is also an acceptable black-andwhite broadcast, and the potential audience for any such broadcast includes not merely those who have at the time of the broadcast equipped themselves with color-television receivers, but also all viewers equipped with black-and-white receivers. A signal for color television which bears this relation to an existing signal for monochrome television, is said to be compatible with the monochrome signal; the importance of compatibility in bringing about early and widespread adoption of color television, once the
A. V. Loughren: Color Television
327