Transcoder
First Claim
1. A transcoder for reversing the phase of one of two signal components of a quadrature amplitude modulated subcarrier, comprising:
- first means for producing sequential samples of the amplitude of said subcarrier at times corresponding to each axis crossing of each of said signal components;
second means for inverting the polarity of alternate ones of said samples; and
third means for reconstructing said subcarrier from the inverted and non-inverted samples without alteration of the sequence thereof.
0 Assignments
0 Petitions
Accused Products
Abstract
Samples of the amplitude of a quadrature amplitude modulated (QAM) subcarrier signal are taken at times corresponding to each axis crossing of each of the two quadrature related signal components. The polarity of alternate ones of the samples is inverted and the signal is reconstructed from the inverted and non-inverted samples whereby the phase of one of the signal components is reversed without alteration of the phase of the other. Where the QAM signal is a television chrominance signal, means are provided for periodically inhibiting inversion of the samples on alternate lines whereby PAL type chrominance signals may be converted to or from NTSC or NTSC "like" chrominance signals.
-
Citations
17 Claims
-
1. A transcoder for reversing the phase of one of two signal components of a quadrature amplitude modulated subcarrier, comprising:
-
first means for producing sequential samples of the amplitude of said subcarrier at times corresponding to each axis crossing of each of said signal components; second means for inverting the polarity of alternate ones of said samples; and third means for reconstructing said subcarrier from the inverted and non-inverted samples without alteration of the sequence thereof. - View Dependent Claims (4, 5, 6)
-
-
2. A transcoder for reversing the phase of one of two signal components of a quadrature amplitude modulated subcarrier;
- comprising;
first means for producing samples of the amplitude of said subcarrier at times corresponding to each axis crossing of each of said signal components; second means for inverting the polarity of alternate ones of said samples; third means for reconstructing said subcarrier from the inverted and non-inverted samples; and fourth means responsive to a control signal supplied thereto for inhibiting the operation of said second means when said control signal is of a first level and enabling operation of said second means when said control signal is of a second level. - View Dependent Claims (3)
- comprising;
-
7. A transcoder for reversing the phase of one of two signal components of a quadrature amplitude modulated subcarrier, comprising:
-
first means for producing samples of the amplitude of said subcarrier at times corresponding to each axis crossing of each of said signal components; second means for inverting the polarity of alternate ones of said samples; third means for reconstructing said subcarrier from the inverted and non-inverted samples; and wherein said second means comprises; circuit means for producing inverted samples; switch means responsive in a first position for coupling said samples produced by said first means to said third means and responsive in a second position for coupling said inverted samples between said circuit means and said third means; and means for changing the position of said switch means at a rate equal to half the sampling rate. - View Dependent Claims (8, 9)
-
-
10. In video reproducer apparatus of the type including a source of composite video signals, a filter for separating said composite signal into a luminance component and a chrominance component, said chrominance component comprising a pair of quadrature related color difference components U and V of non-alternating phase and a burst component having a phase angle of substantially 45°
- relative to one of said components, a chrominance transcoder for converting said chrominance signal to PAL form and circuit means for combining the luminance and converted chrominance signals to provide a PAL type output signal, the improvement for providing said conversion without demodulation to base band wherein said chrominance transcoder comprises;
means for sampling said chroninance input signal at a rate of four times a given subcarrier frequency, the sampling instants being taken at times corresponding to the axis crossings of said U and V components; means for reversing the polarity of alternate samples during every other horizontal scanning interval; and
signal from the inverted and non-inverted samples.
- relative to one of said components, a chrominance transcoder for converting said chrominance signal to PAL form and circuit means for combining the luminance and converted chrominance signals to provide a PAL type output signal, the improvement for providing said conversion without demodulation to base band wherein said chrominance transcoder comprises;
-
11. In video reproducer apparatus of the type including a source of composite video signals, a filter for separating said composite signal into a luminance component and a chrominance component, said chrominance component comprising a pair of quadrature related color difference components U and V of non-alternating phase and a burst component having a phase angle of substantially 45°
- relative to one of said components, a chrominance transcoder for converting said chrominance signal to PAL form and circuit means for combining the luminance and converted chrominance signals to provide a PAL type output signal, the improvement for providing said conversion without demodulation to base band wherein said chrominance transcoder comprises;
means for sampling said chrominance input signal at a rate of four times a given subcarrier frequency, the sampling instants being taken at times corresponding to the axis crossings of said U and V components; means for reversing the polarity of alternate samples during every other horizontal scanning interval; means for reconstructing a chrominance output signal from the inverted and non-inverted samples; and a frequency transcoder connected in cascade with said chrominance transcoder.
- relative to one of said components, a chrominance transcoder for converting said chrominance signal to PAL form and circuit means for combining the luminance and converted chrominance signals to provide a PAL type output signal, the improvement for providing said conversion without demodulation to base band wherein said chrominance transcoder comprises;
-
12. In a video reproducer apparatus of the type including a source of composite video signals, a filter for separating said composite signal into a luminance component and a chrominance component, said chrominance component comprising a pair of quadrature related color difference components U and V of non-alternating phase and a burst component having a phase angle of substantially 180°
- relative to one of said components, a chrominance transcoder for converting said chrominance signal to PAL form and circuit means for combining the luminance and converted chrominance signals to provide a PAL type output signal, the improvement for providing said conversion without demodulation to base band wherein said chrominance transcoder comprises;
means for shifting the phase of said burst component of said chrominance signal substantially 45°
to provide a modified chrominance signal;means for sampling said modified chrominance signal, the sampling instants being taken at times corresponding to the axis crossings of said U and V components; means for reversing the polarity of alternate samples during every other horizontal scanning interval; and means for reconstructing a chrominance output signal from the inverted and non-inverted samples.
- relative to one of said components, a chrominance transcoder for converting said chrominance signal to PAL form and circuit means for combining the luminance and converted chrominance signals to provide a PAL type output signal, the improvement for providing said conversion without demodulation to base band wherein said chrominance transcoder comprises;
-
13. In a video reproducer apparatus of the type including a source of composite video signals, a filter for separating said composite signal into a luminance component and a chrominance component, said chrominance component comprising a pair of quadrature related color difference components U and V of non-alternating phase and a burst component having a phase angle of substantially 180°
- relative to one of said components, a chrominance transcoder for converting said chrominance signal to PAL form and circuit means for combining the luminance and converted chrominance signals to provide a PAL type output signal, the improvement for providing said converstion without demodulation to base band wherein said chrominance transcoder comprises;
means for shifting the phase of said burst component of said chrominance signal substantially 45°
to provide a modified chrominance signal;means for sampling said modified chrominance signal, the sampling instants being taken at times corresponding to the axis crossings of said U and V components; means for reversing the polarity of alternate samples during every other horizontal scanning interval; means for reconstructing a chrominance output signal from the inverted and non-inverted samples; and a frequency transcoder connected in cascade with said chrominance transcoder.
- relative to one of said components, a chrominance transcoder for converting said chrominance signal to PAL form and circuit means for combining the luminance and converted chrominance signals to provide a PAL type output signal, the improvement for providing said converstion without demodulation to base band wherein said chrominance transcoder comprises;
-
14. A chrominance signal transcoder comprising:
-
first means for producing sequential samples of the amplitude of a chrominance input signal at times corresponding to each axis crossing of each of the color difference signal components of said chrominance signal; second means for inverting the polarity of alternate ones of said samples; third means for inhibiting the operation of said second means during every other line scanning interval associated with said chrominance signal; and fourth means for reconstructing said chrominance signal from said samples without alteration of the sequence thereof. - View Dependent Claims (15)
-
-
16. A chrominance signal transcoder comprising:
-
first means for producing samples of the amplitude of a chrominance signal at times corresponding to each axis crossing of each of the color difference signal components of said chrominance signal; second means for inverting the polarity of alternate ones of said samples; third means for inhibiting the operation of said second means during every other line scanning interval associated with said chrominance signal; fourth means for reconstructing said chrominance signal from said samples; and phase shifting means connected in cascade with said transcoder for imparting a phase shift of substantially 45°
to the burst component of said chrominance signal.
-
-
17. A chrominance signal transcoder comprising:
-
first means for producing samples of the amplitude of a chrominance signal at times corresponding to each axis crossing of each of the color difference signal components of said chrominance signal; second means for inverting the polarity of alternate ones of said samples; third means for inhibiting the operation of said second means during every other line scanning interval associated with said chrominace signal; fourth means for reconstructing said chrominance signal from said samples; and phase shifting means for imparting a phase shift of substantially 45°
to the burst component of the reconstructed chrominance signal.
-
Specification