Continuous information add-on system

Claim 3

A system as specified in claim 1 wherein said carrier frequency is an odd multiple of one-quarter of the frequency at which said time-successive line intervals occur.

Claim 4

A system as specified in claim 1 wherein said selected portion of said frequency band lies between the normal location of the luminance and chrominance carrier frequencies of said TV signal.

Claim 5

A system as specified in claim 1 wherein the modulation of said first and second add-on signal components is amplitude modulation.

Claim 6

A system as specified in claim 1 wherein the modulation of said first and second add-on signal components is phase modulation.

Claim 7

A transmitter for use in a system for compatibly transmitting and receiving both a TV signal and an add-on signal within the frequency band occupied by said TV signal, comprising: means for supplying a TV signal occupying a predetermined frequency band and containing video information during time-successive line intervals; means, responsive to said add-on information representative signal, for generating first and second modulated add-on signal components in phase quadrature at a common carrier frequency lying within a selected portion of said frequency band, wherein the modulation of said first add-on signal component is representative of said selected add-on information during the successive line intervals and wherein during each line interval the modulation of said second add-on signal component is representative of identical but opposite polarity add-on information as that represented by the modulation of said first add-on signal component during corresponding portions of the preceding line interval; means for combining said TV signal and said first and second add-on signal components to develop a combined TV and add-on signal suitable for transmission in a common frequency band to a remote receiver.

Claim 8

A transmitter for use in a system for compatibly transmitting and receiving both a TV signal and an add-on signal within the frequency band occupied by said TV signal, comprising: means for supplying a TV signal occupying a predetermined frequency band and containing video information during time-successive line intervals; means, responsive to said add-on information representative signal, for generating first and second modulated add-on signal components in phase quadrature at a common carrier frequency lying within a selected portion of said frequency band, wherein the modulation of said first add-on signal component is representative of said selected add-on information during the successive line intervals and wherein during each line interval the modulation of said second add-on signal component is representative of identical but opposite polarity add-on information as that represented by the modulation of said first add-on signal component during corresponding portions of the preceding line interval; means for combining said TV signal and said first and second add-on signal components to develop a combined TV and add-on signal suitable for transmission in a common frequency band to a remote receiver.

Claim 9

A transmitter as specified in claim 6 wherein said means for generating first and second add-on signal components comprises: means for generating an add-on signal carrier within a selected portion of said frequency band, said add-on carrier having a frequency which is an odd-multiple of one-quarter the frequency at which said time-successive line intervals occur; means for supplying a signal representative of selected add-on information; means for modulating said add-on carrier with said add-on information representative signal, thereby developing said first add-on signal component; and means, responsive to said first add-on signal component, for developing said second add-on signal component directly therefrom.

Claim 10

A transmitter, as specified in claim 7 wherein said means for developing said second add-on signal component comprises means, responsive to said first add-on signal component, for delaying said first add-on signal component by a period equal to the time period between corresponding portions of said time-successive line intervals, and means for inverting said delayed first add-on signal component, thereby developing said second add-on signal component.

Claim 11

A transmitter as specified in claim 6 wherein said means for generating first and second add-on signal components comprises: means for generating an add-on signal carrier within a selected portion of said frequency band, said add-on carrier having a frequency which is an odd multiple of one-quarter the frequency at which said time-successive line intervals occur; means for supplying a signal representative of selected add-on information; means for modulating said add-on carrier with said add-on information representative signal, thereby developing said first add-on signal component; means for delaying said add-on information representative signal by a period equal to the time period between corresponding portions of time-succesSive line intervals; means for phase shifting said add-on signal carrier by a selected amount; means for modulating said phase-shifted add-on signal carrier with said delayed add-on information representative signal, thereby developing said second add-on signal component.

Claim 12

A transmitter for use in a system for compatibly transmitting and receiving both a TV signal and an add-on signal within the frequency band occupied by said TV signal, comprising: means for supplying a TV signal occupying a predetermined frequency band and containing video information during time successive line intervals; means for generating an add-on signal carrier within a portion of said frequency band between the normal location of the luminance and chrominance carrier frequencies of said TV signal, said add-on carrier having a frequency which is an odd multiple of one-quarter the frequency at which said time successive line intervals occur; means for supplying a signal representative of selected add-on information; means for modulating said add-on carrier with said add-on information representative signal to develop a first modulated add-on signal component whose modulation is representative of said selected add-on information during time successive line intervals; means for delaying said first add-on signal component by a period equal to the time period between corresponding portions of said time-successive line intervals; means for inverting said delayed first add-on signal component to develop a second modulated add-on signal component in phase quadrature with said first add-on signal wherein during each line interval the modulation of component, said second add-on signal component is representative of identical but opposite polarity add-on information as that represented by the modulation of said first add-on signal component during corresponding portions of the preceding line interval; and means for combining said TV signal and said first and second add-on signal components to develop a combined TV and add-on signal suitable for transmission in a common frequency band to a remote receiver.

Claim 13

A transmitter for use in a system for compatibly transmitting and receiving both a TV signal and an add-on signal within the frequency band occupied by said TV signal, comprising: means for supplying a TV signal occupying a predetermined frequency band and containing video information during time successive line intervals; means for generating an add-on signal carrier within a portion of said frequency band between the normal location of the luminance and chrominance carrier frequencies of said TV signal, said add-on carrier having a frequency which is an odd multiple of one-quarter the frequency at which said time successive line intervals occur; means for supplying a signal representative of selected add-on information; means for modulating said add-on carrier with said add-on information representative signal to develop a first modulated add-on signal component whose modulation is representative of said selected add-on information during time successive line intervals; means for delaying said first add-on signal component by a period equal to the time period between corresponding portions of said time-successive line intervals; means for inverting said delayed first add-on signal component to develop a second modulated add-on signal component in phase quadrature with said first add-on signal wherein during each line interval the modulation of component, said second add-on signal component is representative of identical but opposite polarity add-on information as that represented by the modulation of said first add-on signal component during corresponding portions of the preceding line interval; and means for combining said TV signal and said first and second add-on signal components to develop a combined TV and add-on signal suitable for transmission in a common frequency band to a remote receiver.

Claim 14

A receiver, for use in a system for compatibly transmitting and receiving a combined signal comprising a TV signal and an add-on signal within the frequency band occupied by said TV signal, wherein said TV signal occupies a predetermined frequency band and contains video information during time-successive line intervals, and wherein said add-on signal comprises first and second modulated add-on signal components in phase quadrature at a common carrier frequency lying within a selected portion of said frequency band, wherein the modulation of said first component is representative of selected add-on information during time successive line intervals and wherein during each line interval the modulation of a second add-on signal component is representative of identical but opposite polarity add-on information as that represented by the modulation of said first add-on signal component during corresponding portions of the preceding line interval said receiver comprising: means for receiving said combined signal; and means for processing said received combined signal to develop an output signal primarily representative of said add-on information.

Claim 15

A receiver, for use in a system for compatibly transmitting and receiving a combined signal comprising a TV signal and an add-on signal within the frequency band occupied by said TV signal, wherein said TV signal occupies a predetermined frequency band and contains video information during time-successive line intervals, and wherein said add-on signal comprises first and second modulated add-on signal components in phase quadrature at a common carrier frequency lying within a selected portion of said frequency band, wherein the modulation of said first component is representative of selected add-on information during time successive line intervals and wherein during each line interval the modulation of a second add-on signal component is representative of identical but opposite polarity add-on information as that represented by the modulation of said first add-on signal component during corresponding portions of the preceding line interval said receiver comprising: means for receiving said combined signal; and means for processing said received combined signal to develop an output signal primarily representative of said add-on information.

Claim 16

A receiver as specified in claim 11 wherein said means for processing said received combined signal comprises means for causing redundant TV video information occurring during time-successive line intervals to tend to cancel and for causing add-on information represented by the modulation of said first add-on signal component to tend to reinforce with identical add-on information represented by the modulation of said second add-on signal component, thereby to develop an output signal primarily representative of said add-on information.

Claim 17

A receiver as specified in claim 12 wherein said means for processing said received combined signal comprises means for delaying said rEceived combined signal by a period equal to the time period between corresponding portions of time successive line intervals, means for inverting said delayed received combined signal, and means for adding said delayed, inverted received combined signal to the undelayed, uninverted received combined signal, thereby to cause redundant TV video information to tend to cancel and to cause said add-on information represented by the modulation of said first add-on signal component to tend to reinforce with said identical add-on information represented by the modulation of said second add-on signal component.

Claim 18

A receiver as specified in claim 13 which additionally includes a synchronous detector coupled to the output of said adding means for demodulating said reinforced add-on signal components and developing an output signal primarily representative of said add-on information.

Claim 19

A receiver as specified in claim 12 wherein said means for processing said received combined signal comprises means for detecting said add-on information represented by the modulation of said first add-on signal component, means for detecting said add-on information represented by the modulation of said second add-on signal component, means for delaying the detected add-on information represented by said first add-on signal component by a period equal to the time period between corresponding portions of time-successive line intervals, and means for combining the detected add-on information represented by said second add-on signal component with the delayed detected add-on information represented by said first add-on signal component, whereby said delayed and undelayed add-on information tends to reinforce whereas redundant TV video information occurring during time-successive line intervals tends to cancel.

Claim 20

A receiver as specified in claim 15 wherein said means for detecting said first and second add-on signal components each comprises a synchronous detector.

Claim 21

A receiver as specified in claim 12 which additionally includes TV display means for displaying said received combined signal, whereby said first and second add-on signal components, having opposite polarity during corresponding portions of time successive line intervals, tend to cancel in the displayed image.