Digital processing of PAL color television signals in the form of a Y signal and a composite U+V/U-V signal

Claim 2

Apparatus for generating digital PAL chrominance signals, the apparatus including input means for receiving television signals comprising chroma signals U and V of PAL type, combining means coupled to the input means and operative to form the sum U + V of the signals U and V on one television line and their difference U - V on the next, and digitising means for digitising the signals with a sampling frequency substantially equal to the PAL colour subcarrier frequency.

Claim 3

Apparatus according to claim 1, including comb filter means for averaging the content of each two succesive lines.

Claim 4

Apparatus according to claim 2, wherein the comb filter means includes a one-line delay and means for linearly combining the input and output of the delay.

Claim 5

Apparatus according to claim 1, wherein the input means is adapted to receive television signals comprising a luminance signal Y, and the digitising means is adapted to digitise the luminance signal with a sampling frequency substantially equal to twice the PAL colour subcarrier frequency.

Claim 6

Apparatus according to claim 1, wherein the input means comprises two input terminals for receiving respectively U and V television signals, and including means for inverting the polarity of the V signal on alternate lines.

Claim 7

Apparatus according to claim 5, including two comb filters for averaging the content of each of two successive lines of the U and V signals respectively.

Claim 8

Apparatus according to claim 6, wherein each comb filter comprises a one line delay and a half-adder connected to the input and output of the delay.

Claim 9

Apparatus according to claim 1, wherein the input means comprises an input terminal for receiving an encoded PAL television signal.

Claim 10

Apparatus according to claim 8, including a one line delay connected to the input terminal, and means for linearly combining the input and output of the delay.

Claim 11

Apparatus according to claim 9, including a filter connected to the output of the linearly combining means for stopping frequencies below a frequency substantially equal to twice the PAL colour subcarrier frequency less the highest frequency of the PAL signal, the output of this filter being sampled at the PAL colour subcarrier frequency.

Claim 12

Apparatus according to claim 10, wherein the output of the filter is also subtracted from the output of the delay and the resultant sampled at twice the colour subcarrier frequency at predetermined positions where the chrominance signal passes through zero, to provide a digital luminance signal.

Claim 15

A method of generating an encoded PAL television signal from a luminance signal Y and a composite chrominance signal U + V / U - V generated by the method of claim 12, comprising modulating the composite chrominance signal onto a PAL colour subcarrier, linearly combining the modulated signal with the signal, stopping frequencies in the combined signal which are below a frequency substantially equal to twice the PAL subcarrier frequency less the highest frequency of the PAL signal, comb filtering the resultant signal through a comb filter which averages the content of each two successive lines, and adding the filtered signal to the luminance signal to provide an encoded PAL signal.

Claim 16

Apparatus for generating an encoded PAL colour television signal from a luminance signal Y and a composite signal U + V / U - V, comprising a modulator for modulating the composite chrominance signal onto a PAL colour subcarrier, means for linearly combining the modulated signal with the luminance signal, a filter for stopping frequencies in the combined signal which are below a frequency substantially equal to twice the PAL colour subcarrier frequency less the highest frequency of the PAL signal, a comb filter connected to receive the resultant signal for averaging the content of each two successive lines, and an adder for adding the comb filtered signal to the luminance signal to provide at an output an encoded PAL signal.

Claim 17

Apparatus for generating an encoded PAL colour television signal from a luminance signal Y and a composite signal U + V / U - V, comprising a modulator for modulating the composite chrominance signal onto a PAL colour subcarrier, means for linearly combining the modulated signal with the luminance signal, a filter for stopping frequencies in the combined signal which are below a frequency substantially equal to twice the PAL colour subcarrier frequency less the highest frequency of the PAL signal, a comb filter connected to receive the resultant signal for averaging the content of each two successive lines, and an adder for adding the comb filtered signal to the luminance signal to provide at an output an encoded PAL signal.

Claim 18

A chrominance combiner circuit for PAL signals comprising: U and V signal inputs; a one-line delay coupled to each input; a half-adder having inputs coupled across each delay; an inverter selectively coupled to the output of the V-signal half-adder to invert alternate lines; an adder coupled to the outputs of the U-signal half-adder and the inverter; and a sampling circuit coupled to the output of the adder to sample the signal applied thereto at the PAL colour subcarrier frequency, whereby a sampled signal is produced consisting of U + V on one line and U-V on the alternate lines.

Claim 19

A chrominance combiner circuit for PAL signals comprising: U and V signal inputs; a one-line delay coupled to each input; a half-adder having inputs coupled across each delay; an inverter selectively coupled to the output of the V-signal half-adder to invert alternate lines; an adder coupled to the outputs of the U-signal half-adder and the inverter; and a sampling circuit coupled to the output of the adder to sample the signal applied thereto at the PAL colour subcarrier frequency, whereby a sampled signal is produced consisting of U + V on one line and U-V on the alternate lines.

Claim 20

A PAL encoder comprising: a Y signal input; a chrominance signal input for receiving a composite chrominance signal comprising U + V on one line and U-V on alternate lines; a halving subtractor having its non-inverting input coupled to the Y signal input and its inverting input coupled to the chrominance signal input; a band-pass filter coupled to the output of the halving subtractor for passing frequencies in the chrominance modulation signal frequency range; a subtractor having its non-inverting input coupled to the Y signal input and its inverting input coupled to the output of the band-pass filter; a one-line delay coupled to the output of the bandpass filter; and an adder coupled to the outputs of the subtractor and the one-line delay.

Claim 21

A PAL encoder comprising: a Y signal input; a chrominance signal input for receiving a composite chrominance signal comprising U + V on one line and U-V on alternate lines; a halving subtractor having its non-inverting input coupled to the Y signal input and its inverting input coupled to the chrominance signal input; a band-pass filter coupled to the output of the halving subtractor for passing frequencies in the chrominance modulation signal frequency range; a subtractor having its non-inverting input coupled to the Y signal input and its inverting input coupled to the output of the band-pass filter; a one-line delay coupled to the output of the bandpass filter; and an adder coupled to the outputs of the subtractor and the one-line delay.

Claim 22

In a television studio system, processing means comprising: first processing circuitry adapted to operate upon a luminance signal Y; and second processing circuitry adapted to operate upon a composite chrominance signal comprising U + V and U-V on alternate lines, the second processing circuitry being coupled to the first processing circuitry for control in parallel therewith.

Claim 23

In a television studio system, processing means comprising: first processing circuitry adapted to operate upon a luminance signal Y; and second processing circuitry adapted to operate upon a composite chrominance signal comprising U + V and U-V on alternate lines, the second processing circuitry being coupled to the first processing circuitry for control in parallel therewith.