Method and apparatus for canceling quadrature distortion as for video signals having in-phase and quadrature phase components

In apparatus for receiving television signal having a first and second quadrature phase related picture carrier signals modulated by a main video signal and a supplementary video signal, respectively, wherein the second modulated carrier signal has unequal sidebands which add undesirable crosstalk distortion signal components to said first modulated carrier signal, apparatus for separating the main and supplementary video signals from said received television signal, comprising:

• means for receiving said television signal;
• first and second synchronous detecting means, for demodulating said television signal to recover said main and supplementary video signals, wherein the recovered main video signal includes said quadrature crosstalk distortion components;
• vestigial sideband filter means coupled between said means for receiving said television signal and said first and second demodulating means for filtering said received television signal to substantially eliminate out-of-band signal components from the signal applied to said first and second demodulating means;
• phase translating filter means, coupled to receive said recovered supplementary video signal for generating a phase translated supplementary video signal which, when combined with said recovered main video signal, substantially cancels the quadrature crosstalk distortion components in a first frequency range of the main video signal and said phase translating filter means includes means for converting the quadrature crosstalk distortion components of the main video signal into signal components that are in-phase with said recovered main video signal in a second frequency range of said main video signal;
• and
• means for combining said phase translated supplementary video signal with said recovered main video signal.

In a television receiver for receiving a television signal having a vestigial sideband modulated main video signal component and an inverse Nyquist filtered, double sideband modulated supplementary video signal component, apparatus for recovering said main and supplementary video signal components comprising:

• means for receiving said television signal;
• vestigial sideband filter means for filtering said received television signal to substantially eliminate out-of-band signals;
• first and second synchronous demodulating means for generating recovered main and supplementary video signals, respectively, from said filtered television signal, wherein said each of said recovered main and supplementary video signals includes undesirable quadrature crosstalk distortion signal components related to said supplementary video signal and to said main video signal, respectively;
• phase translating filter means for filtering said recovered supplementary video signal to generate a phase translated recovered secondary signal which, when combined with said recovered main video signal, substantially cancels the quadrature distortion components of said supplementary video signal in said main video signal and converts the quadrature distortion components of said main video signals in said supplementary video signal into in-phase signal components which reenforce said recovered main video signal;
• and
• means for combining the phase translated recovered secondary video signal with the recovered main video signal.

In a television receiver for receiving a television signal having a vestigial sideband modulated main video signal component and an inverse Nyquist filtered double sideband supplementary video signal component, a method of recovering said main and supplementary video signal components comprising the steps of:

• receiving said television signal;
• filtering said received television signal to substantially eliminate out-of-band signal components;
• demodulating the filtered television signal to generate recovered main and supplementary video signals, wherein said each of said recovered main and supplementary video signals includes undesirable quadrature crosstalk distortion signal components related to said supplementary video signal and to said main video signal, respectively;
• filtering said recovered supplementary video signal using a phase translating filter to generate a phase translated recovered secondary signal which, when combined with said recovered main video signal, substantially cancels the quadrature distortion components of said supplementary video signal and converts the quadrature distortion components of said main video signals into in-phase signal components which reenforce said recovered main video signal;
• and
• combining the phase translated recovered secondary video signal with the recovered main video signal.

In apparatus for receiving a television signal having first and second quadrature phase related picture carrier signals modulated by a main video signal and a supplementary video signal, respectively, wherein the received television signal includes multipath signal components, and said first modulated carrier signal includes undesirable crosstalk distortion signal components from the second modulated carrier signal ,circuitry for processing said television signal comprising:

• first and second synchronous detecting means, for demodulating said television signal to recover said main and supplementary video signals;
• complex deghosting apparatus having first and second input terminals coupled respectively to said first and second synchronous detecting means, for producing at first and second output terminals, respectively, said main video signal and said supplementary video signal, substantially free of said multipath signal components;
• Hilbert filter means, coupled to the second output terminal of said deghosting means, for generating a phase translated supplementary video signal which, when combined with deghosted main video signal, substantially cancels the quadrature crosstalk distortion components;
• and
• means coupled to said first output terminal of said deghosting means and said Hilbert filter means for combining said phase translated supplementary video signal and deghosted main video signal to produce main video signal substantially free of said multipath signal components and said quadrature crosstalk distortion components.