Dropout compensator for pal color television

Claim 2

A dropout compensator for the PAL color television system wherein the video signal contains luminance information and color information and wherein alternate lines of the color information are the conjugate of each other and with an additional quarterline offset in phase between alternate lines, including first means responsive to each line of the luminance information for delaying the lines of luminance information a first predetermined period of time to produce from the first means a first output signal which may be substituted for the luminance information upon the occurrence of a dropout in the video signal, second means responsive to each line of the color information for delaying the lines of color information a second predetermined period of time to produce a second output signal, third means coupled to the second means and responsive to the second output signal for producing a modified second output signal which has lines of information which are the conjugate of the lines of information of the second output signal and which is compensated for the quarter-line offset between alternate lines which modified second output signal may be substituted for the color information upon the occurrence of a dropout in the video signal, fourth means for switching and with the fourth means receiving the video signal as a first input and for receiving the first output signal and the modified second output signal as a second input and for passing either the first or second input signals through the fourth means, and fifth means responsive to the video signal for detecting dropouts in the video signal and with the fifth means coupled to the fourth means to control the fourth means to pass the second input signal when the fifth means detects a dropout in the video signal.

Claim 3

The dropout compensator of claim 1 wherein the second means provides a delay of approximately two scanning lines to produce a phase inverted second output signal having characteriStics similar to the color information and wherein the third means provides for a phase inversion of the second output signal.

Claim 4

The dropout compensator of claim 1 wherein the second means provides for a delay of approximately one scanning line and wherein the third means includes a summing network to provide for a summing of the second output signal and the color information to average the error between the color information and the second output signal and with the third means also including a delay means for providing a delay of approximately one scanning line.

Claim 5

The dropout compensator of claim 1 wherein the second means provides for a delay of approximately one scanning line and wherein the third means includes a balanced modulator responsive to the second output signal for modulating the second output signal to produce the modified second output signal including a portion having characteristics similar to the color information.

Claim 6

In a dropout compensator for the PAL color television system wherein alternate lines of color information are the conjugate of each other and have a quarter-line offset between alternate lines wherein the dropout compensator is of the type wherein a dropout compensating signal is formed from the color information and is used in place of the color information when a dropout occurs, means for forming the dropout compensating signal, including first means responsive to the color information for delaying the lines of color information a predetermined period of time to produce a first output signal, and second means coupled to the first means and responsive to the first output signal for producing a modified first output signal having lines which are the conjugate of the lines of color information of the first output signal and which is compensated for the quarter-line offset and which modified first output signal may be used in place of the color information when a dropout occurs in the color information.

Claim 7

In a dropout compensator for the PAL color television system wherein alternate lines of color information are the conjugate of each other and have a quarter-line offset between alternate lines wherein the dropout compensator is of the type wherein a dropout compensating signal is formed from the color information and is used in place of the color information when a dropout occurs, means for forming the dropout compensating signal, including first means responsive to the color information for delaying the lines of color information a predetermined period of time to produce a first output signal, and second means coupled to the first means and responsive to the first output signal for producing a modified first output signal having lines which are the conjugate of the lines of color information of the first output signal and which is compensated for the quarter-line offset and which modified first output signal may be used in place of the color information when a dropout occurs in the color information.

Claim 8

In the dropout compensator of claim 5 wherein the first means provides a delay of approximately two scanning lines to produce a phase inverted first output signal having characteristics similar to the color information and wherein the second means provides for a phase inversion of the first output signal.

Claim 9

In the dropout compensator of claim 5 wherein the first means provides for a delay of approximately one scanning line and wherein the second means includes a summing network to provide for a summing of the first output signal and the color information to average the error between the color information and the first output signal and with the second means also including a delay means for providing a delay of approximately one scanning line.

Claim 10

In the dropout compensator of claim 5 wherein the first means provides for a delay of approximately one scanning line and wherein the second means includes a balanced modulator responsive to the first output signal for modulating the first output signal to produce the modified first output signal including a signal having characteristics similar to the color information.

Claim 11

In a dropout compensator for the PAL color television system wherein the video signal includes color information and wherein alternate lines of color information are the conjugate of each other and wherein the dropout compensator is of the type wherein a dropout compensating signal is formed from the color information and is used in place of the color information when a dropout occurs, means for forming the dropout compensating signal, including first means responsive to the video signal for passing the color information and blocking other information, second means coupled to the first means for delaying the color information approximately two scanning lines but with a phase inversion to provide a phase inverted delayed color information signal, and third means coupled to the second means for phase inverting the phase inverted delay color information signal.

Claim 12

In a dropout compensator for the PAL color television system wherein the video signal includes color information and wherein alternate lines of color information are the conjugate of each other and wherein the dropout compensator is of the type wherein a dropout compensating signal is formed from the color information and is used in place of the color information when a dropout occurs, means for forming the dropout compensating signal, including first means responsive to the video signal for passing the color information and blocking other information, second means coupled to the first means for delaying the color information approximately two scanning lines but with a phase inversion to provide a phase inverted delayed color information signal, and third means coupled to the second means for phase inverting the phase inverted delay color information signal.

Claim 13

In the dropout compensator of claim 9 wherein each succeeding line of color information is offset from the previous line and wherein the second means includes a delay to compensate for the offset.

Claim 14

In the dropout compensator of claim 9 wherein the second means is a fixed delay line and additionally including an adjustable delay line adjusted to provide the proper delay in the system.

Claim 15

In a dropout compensator for the PAL color television system wherein alternate lines of color information are the conjugate of each other and wherein the dropout compensator is of the type wherein a dropout compensating signal is formed from the color information and is used in place of the color information when a dropout occurs, means for forming the dropout compensating signal, including first means responsive to the color information for providing a delay of the color information for approximately one scanning line, second means responsive to the color information for providing a phase inversion of the color information, third means responsive to the color information, the phase inverted color information and the delayed color information for producing from the color information, the phase inverted color information and the delayed color information an averaged output signal which is the conjugate of the color information and has an average error component; and fourth means responsive to the averaged output signal for providing a delay of the averaged output signal of approximately one scanning line to produce a color dropout compensating signal.

Claim 16

In a dropout compensator for the PAL color television system wherein alternate lines of color information are the conjugate of each other and wherein the dropout compensator is of the type wherein a dropout compensating signal is formed from the color information and is used in place of the color information when a dropout occurs, means for forming the dropout compensating signal, including first means responsive to the color information for providing a delay of the color information for approximately one scanning line, second means responsive to the color information for providing a phase inversion of the color information, third means responsive to the color information, the phase inverted color information and the delayed color information for producing from the color information, the phase inverted color information and the delayed color information an averaged output signal which is the conjugate of the color information and has an average error component; and fourth means responsive to the averaged output signal for providing a delay of the averaged output signal of approximately one scanning line to produce a color dropout compensating signal.

Claim 17

In the dropout compensator of claim 12 wherein the third means includes a pair of summing networks and wherein one summing network sums the color information and the delayed color information and wherein the other summing network sums the phase inverted color information and the delayed color information and wherein the outputs of the summing networks are added together.

Claim 18

In the dropout compensator of claim 12 wherein each succeeding line of color information is offset from the previous line and wherein the first means and the fourth means each provide a delay to compensate for the offset.

Claim 19

In a dropout compensator for the PAL color television system wherein alternate lines of color information are the conjugate of each other and wherein the dropout compensator is of the type wherein a dropout compensating signal is formed from the color information and is used in place of the color information when a dropout occurs, means for forming the dropout compensating signal, including first means responsive to the color information for providing a delay of the color information of approximately one scanning line, second means responsive to the color information and the delayed color information for summing the color information and the delayed color information to produce a control signal, third means for providing an oscillating signal and with the third means responsive to the control signal to lock the frequency of the oscillating signal in accordance with the control signal, and fourth means responsive to the oscillating signal and the delayed color information signal for modulating the delayed color information signal with the oscillating signal to produce an output signal including a portion having characteristics similar to the color information.

Claim 20

In a dropout compensator for the PAL color television system wherein alternate lines of color information are the conjugate of each other and wherein the dropout compensator is of the type wherein a dropout compensating signal is formed from the color information and is used in place of the color information when a dropout occurs, means for forming the dropout compensating signal, including first means responsive to the color information for providing a delay of the color information of approximately one scanning line, second means responsive to the color information and the delayed color information for summing the color information and the delayed color information to produce a control signal, third means for providing an oscillating signal and with the third means responsive to the control signal to lock the frequency of the oscillating signal in accordance with the control signal, and fourth means responsive to the oscillating signal and the delayed color information signal for modulating the delayed color information signal with the oscillating signal to produce an output signal including a portion having characteristics similar to the color information.

Claim 21

In the dropout compensator of claim 15 wherein the third means produces an oscillating signal having twice the frequency of the control signal.

Claim 22

In the dropout compensator of claim 15 wherein the oscillating signal is twice the frequency of the control signal and wherein the fourth means is a balanced modulator and with the output signal including a first portion of the output signal at the frequency of the control signal and including a second portion of the output signal at three times the frequency of the control signal and additionally including means for passing the first portion of the output signal and blocking the seconD portion of the output signal.

Claim 23

In a dropout compensator for the PAL color television system wherein alternate lines of color information are the conjugate of each other and wherein the dropout compensator is of the type wherein a dropout compensating signal is formed from the color information and is used in place of the color information when a dropout occurs, means for forming the dropout compensating signal, including first means responsive to the color information for providing a delay of the color information of approximately one scanning line, second means responsive to the color information and the delayed color information for summing the color information and the delayed color information to produce a first control signal, third means responsive to the color information and the delayed color information for phase inverting the color information and for summing the phase inverted color information and the delayed color information to produce a second control signal, fourth means for frequency doubling the first and second control signals, fifth means for phase inverting the first frequency doubled control signal relative to the second frequency doubled control signal, sixth means for providing an oscillating signal and with the sixth means responsive to the frequency doubled control signals to lock the frequency of the oscillating signal in accordance with the frequency of the control signals, and seventh means responsive to the oscillating signal and the delayed color information signal for modulating the delayed color information signal with the oscillating signal to produce an output signal including a portion having characteristics similar to the color information. 19 In the dropout compensator of claim 18 wherein the sixth means produces an oscillating signal having the same frequency as the frequency doubled control signals.

Claim 24

In the dropout compensator of claim 18 wherein the oscillating signal is twice the frequency of the first and second control signals and wherein the seventh means is a balanced modulator and with the output signal including a first portion of the output signal at the frequency of the first and second control signals and including a second portion of the output signal at three times the frequency of the first and second control signals and additionally including means for passing the first portion of the output signal and blocking the second portion of the output signal.