Method of reproducing a chrominance signal from a previously low-range-converted chrominance signal using comb filtering and sampling

A method of reproducing a carrier chrominance signal with a carrier having a prescribed carrier frequency f.sub.SC from a low-range-converted chrominance signal with a carrier having a low-range-converted carrier frequency f.sub.C, comprising the steps of:

• sampling said low-range-converted chrominance signal at a frequency nf.sub.C to obtain a sampled low-range-converted chrominance signal, where n is an integer;
• decoding said sampled low-range-converted chrominance signal using an oscillation signal having said frequency f.sub.C and a phase which has a predetermined relationship to that of the carrier of said low-range-converted chrominance signal to obtain two color difference signals;
• filtering said two color difference signals for eliminating even order harmonic components of said two color difference signals and noise components, said filtering step comprising the steps of:
• delaying said two color difference signals by a predetermined time;
• and adding said two color difference signals and the delayed two color difference signals, respectively;
• sampling said two color difference signals after they have been filtered at a frequency mf.sub.SC to obtain two sampled color difference signals, where m is an integer;
• and
• encoding said two sampled color difference signals using an oscillation signal having said frequency f.sub.SC to obtain said carrier chrominance signal.

A method of reproducing a carrier chrominance signal with a carrier having a prescribed carrier frequency f.sub.SC from a low-range-converted chrominance signal with a carrier having a low-range-converted carrier frequency f.sub.C, comprising the steps of:

• sampling said low-range-converted chrominance signal at a sampling frequency 4f.sub.C to obtain a sampled low-range-converted chrominance signal;
• inverting said sampled low-range-converted chrominance signal at cycles of 2f.sub.C to obtain an alternately inverting low-range-converted chrominance signal which alternately inverts at intervals of 1/(2f.sub.C);
• sampling said alternately inverting low-range-converted chrominance signal with a first clock signal having a frequency 2f.sub.C and a second clock signal having said frequency 2f.sub.C and a phase shifted by 180.degree. from that of said first clock signal to obtain two color difference signals;
• filtering said two color difference signals for eliminating even order harmonic components of said two color difference signals and noise components, said filtering step comprising the steps of:
• delaying said two color difference signals by a predetermined time;
• and adding said two color difference signals and the delayed two color difference signals, respectively;
• sampling said two color difference signals after they have been filtered at a sampling frequency 4f.sub.SC to obtain two sampled color difference signals;
• and
• encoding said sampled two color difference signals using an oscillation signal having said frequency f.sub.SC to obtain said carrier chrominance signal.

A method of reproducing a carrier chrominance signal with a carrier having a prescribed carrier frequency f.sub.SC from a low-range-converted chrominance signal with a carrier having a low-range-converted carrier frequency f.sub.C, comprising the steps of:

• sampling said low-range-converted chrominance signal at a sample frequency 4f.sub.C to obtain a sampled low-range-converted chrominance signal;
• inverting said sampled low-range-converted chrominance signal at cycles of 2f.sub.C to obtain an alternately inverting low-range-converted chrominance signal which alternately inverts at intervals of 1/(2f.sub.C);
• sampling and holding said alternately inverting low-range-converted chrominance signals with a first clock signal having a frequency 2f.sub.C and a second clock signal having said frequency 2f.sub.C and a phase shifted by 180.degree. from that of said first clock signal to obtain two color difference signals each having a sampled frequency 2f.sub.C ;
• sampling the sampled and held two color difference signals each having said sampled frequency 2f.sub.C at a sampling frequency 4f.sub.C to obtain two color difference signals each having a sampled frequency 4f.sub.C ;
• filtering said two color difference signals sampled at said sampling frequency 4f.sub.C for eliminating even order harmonic components of said two color difference signals and noise components, said filtering step comprising the steps of:
• delaying said two color difference signals by a predetermined time;
• and adding said two color difference signals and the delayed two color difference signals, respectively;
• sampling said two color difference signals after they have been filtered at a sampling frequency 4f.sub.SC to obtain two further sampled color difference signals;
• and
• encoding said two further sampled color difference signals using an oscillation signal having said frequency f.sub.SC to obtain said carrier chrominance signal.

A method of reproducing two color difference signals from a low-range-converted chrominance signal with a carrier having a low-range-converted carrier frequency, comprising the steps of:

• demodulating said low-range-converted chrominance signal to obtain two color difference signals;
• and
• filtering said two color difference signals for eliminating even order harmonic components of said two color difference signals and noise components, said filtering step comprising the steps of:
• delaying said two color difference signals by a predetermined time;
• and adding said two color difference signals and the delayed two color difference signals, respectively;
• and
• sampling and holding said two color difference signals after they have been filtered at a predetermined sampling frequency to eliminate high frequency components having frequencies outside of a frequency range of said two color difference signals.

A method of reproducing two color difference signals from a low-range-converted chrominance signal with a carrier having a low-range-converted carrier frequency f.sub.C, comprising the steps of:

• sampling said low-range-converted chrominance signal at a sampling frequency 4f.sub.C to obtain a sampled low-range-converted chrominance signal;
• inverting said sampled low-range-converted chrominance signal at cycles of 2f.sub.C to obtain an alternately inverting low-range-converted chrominance signal which alternately inverts at intervals of 1/(2f.sub.C);
• sampling said alternately inverting low-range-converted chrominance signal with a first clock signal having a frequency 2f.sub.C and a second clock signal having said frequency 2f.sub.C and a phase shifted by 180.degree. from that of said first clock signal to obtain two color difference signals;
• and
• filtering said two color difference signals for eliminating even order harmonic components of said two color difference signals and noise components, said filtering step comprising the steps of:
• delaying said two color difference signals by a predetermined time;
• and adding said two color difference signals and the delayed two color difference signals, respectively.

A method of reproducing two color difference signals from a low-range-converted chrominance signal with a carrier having a low-range-converted carrier frequency f.sub.C, comprising the steps of:

• sampling said low-range-converted chrominance signal at a sampling frequency 4f.sub.C to obtain a sampled low-range-converted chrominance signal;
• inverting said sampled low-range-converted chrominance signal at cycles of 2f.sub.C to obtain an alternately inverting low-range-converted chrominance signal which alternately inverts at intervals of 1/(2f.sub.C);
• sampling and holding said alternately inverting low-range-converted chrominance signal with a first clock signal having a frequency 2f.sub.C and a second clock signal having said frequency 2f.sub.C and a phase shifted by 180.degree. from that of said first clock signal to obtain two color difference signals each having a sampled frequency 2f.sub.C ;
• sampling the sampled and held two color difference signals each having said sampled frequency 2f.sub.C at a sampling frequency 4f.sub.C to obtain two color difference signals each having a sampled frequency 4f.sub.C ;
• and
• filtering said two color difference signals sampled at said sampling frequency 4f.sub.C for eliminating even order harmonic components of said two color difference signals and noise components, said filtering step comprising the steps of:
• delaying said two color difference signals by a predetermined time;
• and adding said two color difference signals and the delayed two color difference signals, respectively.