Hybrid sequential and carrier encoded color television transmission method and circuits
AssigneeBASF SE
InventorBernhard A. Hjortzberg
Life of this patent
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Abstract
A method and circuits for encoding a color video signal for processing, preferably recording and/or playback of said signal within a limited bandwidth of not more than 3MHz without a separate channel for color information such that one half the sum of two sequential horizontal scan lines of information equals the luminance information of the color video signal and one half of the difference of the said two sequential horizontal scan lines of information equals the chrominance information of the color video signal, wherein a first chrominance signal and a second chrominance signal are contained in two non-overlapping frequency regions.
Claims5
A circuit for encoding color video signals which comprises:
- a. a comb filter including a delay line and having two output terminals, the first of said output terminals providing the luminance information and the second of said output terminals providing the chrominance information;
- b. a demodulator connected to the second output terminal of the comb filter, which has two output terminals each of which is connected to a low pass filter each having an output terminal the output terminal of one low pass filter providing (R-Y) and the output terminal of the other low pass filter providing (B-Y);
- c. a first double balanced modulator connected to the (B-Y)-low-pass-filter and transmitting a second chrominance signal, D.sub.b, as an amplitude modulation on a suppressed carrier;
- d. a first adder having two inputs the first of which is connected to the (R-Y)-low-pass-filter and the second of which is connected to the output of the first double balanced modulator and having an output which provides the sum of signals (R-Y) and D.sub.b ;
- e. a second double balanced modulator connected to the output of the first adder and transmitting the signal appearing at its input as an amplitude modulation on a suppressed carrier at its output;
- and
- f. a second adder having two inputs the first of which is connected to the first output terminal of the comb filter and the second of which is connected to the output of the second double balanced modulator, and having an output which provides the encoded signal.
In a system for processing of a color video signal, which system has a bandwidth of not more than 3 mHz, an improved method for processing said color video signal to produce an encoded signal, comprising encoding the color video signal, with substantially no loss of luminance information in said bandwidth, so as to produce a line-sequentially encoded signal in which one half the sum of two successive horizontal scan lines of information equaling the luminance information of the color video signal alternates with one half of the difference of the said two successive horizontal scan lines of information equaling the chrominance information of the color video signal;
- wherein said chrominance information is represented by a first chrominance signal and a second chrominance signal which are contained in two non-overlapping frequency regions;
- and
- wherein the step of encoding the color video signal comprises:
- a. separating the luminance information of the color video signal from the chrominance information of the color video signal;
- b. demodulating said chrominance information of the color video signal into said first chrominance signal and said second chrominance signal;
- c. amplitude modulating a first suppressed carrier by one of said first and second chrominance signals, the frequency of said first carrier being an odd multiple of the video horizontal scan line frequency,
- d. combining the other of said first and second chrominance signals with said first amplitude modulated suppressed carrier,
- e. amplitude modulating a second suppressed carrier by the signal representing the combination of said chrominance signal and said first amplitude modulated suppressed carrier, the frequency of said second carrier being an odd multiple of one half of the video horizontal scan line frequency, and
- f. combining said luminance information of said color video signal with said second amplitude modulated suppressed carrier to produce said signal.
An apparatus for processing of a color video signal comprising:
- a. means for separating the luminance information of the color video signal from the chrominance information of the color video signal;
- b. means for demodulating the chrominance information into a first chrominance signal and a second chrominance signal;
- and
- c. means for processing the luminance information, first chrominance signal, and second chrominance signal to form a line-sequentially encoded signal in which one half the sum of two successive horizontal scan lines of the encoded signal equaling the luminance information of the color video signal alternates with one half of the difference of the two successive horizontal scan lines of the encoded signal equaling the chrominance information of the color video signal;
- wherein said chrominance information is represented by a first chrominance signal and a second chrominance signal which are contained in two non-overlapping frequency regions;
- and
- wherein the means for processing the luminance information, first chrominance signal, and second chrominance signal to form said encoded signal further comprises means for amplitude modulating a first suppressed carrier in dependence on one of said first and second chrominance signals, the frequency of said first suppressed carrier being an odd multiple of the video horizontal scan line frequency, means for combining the other of said first and second chrominance signals with said first amplitude modulated suppressed carrier, means for amplitude modulating a second suppressed carrier by the signal representing the combination of said other chrominance signal and said first amplitude modulated suppressed carrier, the frequency of said second carrier being an odd multiple of one half of the video horizontal scan frequency, and means for combining said luminance information of said color video signal with said second amplitude modulated suppressed carrier, thereby producing said encoded signal.
Dependencies are inferred from the claim text.