NTSC/PAL switchable video color decoder using a digital comb filter and method

Claim 1

A video colour decoder using a digital comb filter, comprising first means for deriving a first analog signal Y1 representing low band luminance component of a video colour input signal Icv; second means for deriving a second analog signal Yhc representing high band luminance and chrominance components of the video colour input signal Icv; third means to enable synchronous demodulation of the second analog signal Yhc to provide a B-Y chrominance component signal U 1 and an R-Y chrominance component signal V 1 (where B and R is the conventional notation for the respective RGB component signals); first analog to digital converter (ADC) means for digitising the first analog signal Y1 to produce the equivalent digital signal Yd1; second analog to digital converter (ADC) means for digitising the (B-Y) and (R-Y) chrominance component signals U 1 V 1 ; first digital delay means for providing a single line delay of the first digital signal Yd1; second digital delays means for providing a single line delay of the chrominance component signals U 1 V 1 with a delay period of one line, the chrominance component signals so delayed by one line period being designated U 0 , V 0 ; third digital delay means for providing a further single line delay of the chrominance signals U 0 ,V 0 with a further delay period of one line, the chrominance component signals so delayed by one further line period being designated U -1 , V -1 ; summing means arranged to reject consistent chrominance information and operable to provide a high band luminance signal Yu as a function of at least two of the respective chrominance component signals U 1 , U 0 and U -1 ; summing means arranged to reject consistent chrominance information and operable to provide a high band luminance signal Yv as a function of at least two of the respective chrominance component signals V 1 ,V 0 and V -1 ; means for generating digital sinewave and cosinewave reference signals Uref, Vref representing the sine wave of the coded (B-Y) subcarrier reference phase signal and the cosinewave of the coded (R-Y) subcarrier reference phase signal; digital means for obtaining the products of the signals Yu,Yv and their respective sinewave and cosinewave reference signals Uref, Vref; means for summing these products to provide a digital high band luminance component signal Yh; and digital means for summing the digital signal Yd1 and the digital signal Yh to provide a digital wide band luminance output signal Yd.

Claim 8

A method of decoding a video colour signal to provide a digital wide band luminance signal comprising the steps of: (a) deriving a first analog signal Y1 representing low band luminance component of a video colour input signal Icv, by passing the video colour input signal Icv through a first analog filter means; (b) deriving a second analog signal Yhc representing high band luminance and chrominance components of the video colour input signal Icv by passing the colour input signal Icv through second means which subtracts the first analog signal Y1 from a correspondingly delayed input signal Icv; (c) synchronously demodulating the second analog signal Yhc to provide a (B-Y) chrominance component signal U 1 and an (R-Y) chrominance component signal V 1 (where B and R is the conventional notation for the respective RGB component signals); (d) employing first analog to digital converter (ADC) means to digitise the first analog signal Y1 thereby to produce the equivalent digital signal Yd1; (e) employing second analog to digital converter (ADC) means to digitise the (B-Y) and (R-Y) chrominance component signals U 1 , V 1 ; (f) employing first digital delay means to provide a single line delay of the first digital signal Yd1; (g) employing digital delay means to provide a single line delay of the chrominance component signals U 1 , V 1 with a delay period of one line, the chrominance component signals so delayed by one line period being designated U 0 ,V 0 ; (h) employing third digital delay means to provide a further single line delay of the chrominance signals U 0 ,V 0 with a further delay period of one line, the chrominance component signals so delayed by one further line period being designated U -1 , V -1 ; (i) employing summing means arranged to reject consistent chrominance information and operable to provide a high band luminance signal Yu as a function of at least two of the respective chrominance component signals U 1 , U 0 and U -1 ; (j) employing summing means arranged to reject consistant chrominance information and operable to provide a high band luminance signal Yv as a function of at least two of the respective chrominance component signals V 1 ,V 0 and V -1 ; (k) generating digital sinewave and cosinewave reference signals Uref, Vref representing the sine wave of the coded (B-Y) subcarrier reference phase signal and the cosine wave of the coded (R-Y) subcarrier reference phase signal; (l) obtaining the products of the signals Yu,Yv and their respective sinewave and cosinewave reference signals Uref,Vref; (m) summing these products to provide a digital high band luminance component signal Yh; (n) and, digitally summing the digital signal Yd1 and the digital signal Yh to provide a digital wide band luminance output signal Yd.

Claim 9

A method of decoding a video colour signal to provide a digital wide band luminance signal comprising the steps of: (a) deriving a first analog signal Y1 representing low band luminance component of a video colour input signal Icv, by passing the video colour input signal Icv through a first analog filter means; (b) deriving a second analog signal Yhc representing high band luminance and chrominance components of the video colour input signal Icv by passing the colour input signal Icv through second means which subtracts the first analog signal Y1 from a correspondingly delayed input signal Icv; (c) synchronously demodulating the second analog signal Yhc to provide a (B-Y) chrominance component signal U 1 and an (R-Y) chrominance component signal V 1 (where B and R is the conventional notation for the respective RGB component signals); (d) employing first analog to digital converter (ADC) means to digitise the first analog signal Y1 thereby to produce the equivalent digital signal Yd1; (e) employing second analog to digital converter (ADC) means to digitise the (B-Y) and (R-Y) chrominance component signals U 1 , V 1 ; (f) employing first digital delay means to provide a single line delay of the first digital signal Yd1; (g) employing digital delay means to provide a single line delay of the chrominance component signals U 1 , V 1 with a delay period of one line, the chrominance component signals so delayed by one line period being designated U 0 ,V 0 ; (h) employing third digital delay means to provide a further single line delay of the chrominance signals U 0 ,V 0 with a further delay period of one line, the chrominance component signals so delayed by one further line period being designated U -1 , V -1 ; (i) employing summing means arranged to reject consistent chrominance information and operable to provide a high band luminance signal Yu as a function of at least two of the respective chrominance component signals U 1 , U 0 and U -1 ; (j) employing summing means arranged to reject consistant chrominance information and operable to provide a high band luminance signal Yv as a function of at least two of the respective chrominance component signals V 1 ,V 0 and V -1 ; (k) generating digital sinewave and cosinewave reference signals Uref, Vref representing the sine wave of the coded (B-Y) subcarrier reference phase signal and the cosine wave of the coded (R-Y) subcarrier reference phase signal; (l) obtaining the products of the signals Yu,Yv and their respective sinewave and cosinewave reference signals Uref,Vref; (m) summing these products to provide a digital high band luminance component signal Yh; (n) and, digitally summing the digital signal Yd1 and the digital signal Yh to provide a digital wide band luminance output signal Yd.