US4048654A — Stereophonic television sound transmission system

Claim 1

Independent Claim 197 words

A stereophonic sound transmission system for transmitting within a television broadcast channel having defined frequency limits left and right audio source signals and a video source signal each having a predetermined upper frequency limit, said video source signal being amplitude-modulated on a video carrier to form an AM signal occupying a first portion of said channel, said system comprising, in combination: generator means including a stereo multiplex generator for generating a composite signal including a first component representative of the sum of said left and right source signals, a second amplitude-modulated subcarrier component representative of the difference between said left and right signals, said subcarrier component having upper and lower sidebands centered about a suppressed subcarrier, and a pilot component having a frequency one-half the frequency of said suppressed subcarrier; transmitter means including means for generating a sound carrier within said broadcast channel, and means for frequency-modulating said sound carrier with said composite signal to form an FM signal occupying a second portion of said channel; receiver means for receiving said television broadcast channel including means for deriving said composite signal; and demodulator means for developing said left and right audio source signals from said composite signal.

Claim 2

Dependent Claim 197 words

A stereophonic sound transmission system for transmitting within a television broadcast channel having defined frequency limits left and right audio source signals and a video source signal each having a predetermined upper frequency limit, said video source signal being amplitude-modulated on a video carrier to form an AM signal occupying a first portion of said channel, said system comprising, in combination: generator means including a stereo multiplex generator for generating a composite signal including a first component representative of the sum of said left and right source signals, a second amplitude-modulated subcarrier component representative of the difference between said left and right signals, said subcarrier component having upper and lower sidebands centered about a suppressed subcarrier, and a pilot component having a frequency one-half the frequency of said suppressed subcarrier; transmitter means including means for generating a sound carrier within said broadcast channel, and means for frequency-modulating said sound carrier with said composite signal to form an FM signal occupying a second portion of said channel; receiver means for receiving said television broadcast channel including means for deriving said composite signal; and demodulator means for developing said left and right audio source signals from said composite signal.

Claim 3

Dependent Claim 23 words

A stereophonic sound transmission system as defined in claim 1 wherein said sound carrier is spaced by 4.5 MHz from said video carrier.

Claim 4

Dependent Claim 38 words

A stereophonic sound transmission system as defined in claim 1 wherein said second component of said composite signal is spaced from said sound carrier by at least twice the maximum upper frequency limit of said audio source signals.

Claim 5

Dependent Claim 44 words

A stereophonic sound transmission system as defined in claim 3 wherein said upper limit of said left and right audio source signals is approximately 15 KHz, the frequency of said suppressed subcarrier is 38 KHz, the frequency of said pilot component is 19 KHz.

Claim 6

Dependent Claim 47 words

A stereophonic sound transmission system as defined in claim 1 wherein said video source signal has a predetermined horizontal scanning frequency, the frequency of said pilot component is 5/4 said horizontal scanning frequency, and the frequency of said subcarrier is twice the frequency of said pilot component.

Claim 7

Dependent Claim 37 words

A stereophonic sound transmission system as defined in claim 1 wherein said upper and lower sidebands each cause a maximum frequency deviation to said frequency-modulated carrier equal to one-half the maximum deviation caused by said first component.

Claim 8

Dependent Claim 50 words

A stereophonic sound transmission system as defined in claim 6 wherein said first component causes a maximum frequency deviation of 22.5 KHz to said frequency-modulated sound carrier and said upper and lower sidebands of said second component each cause a maximum frequency deviation of 11.25 KHz to said sound carrier.

Claim 9

Dependent Claim 25 words

A stereophonic sound transmission system as defined in claim 7 wherein said pilot component causes a maximum deviation of 2.5 KHz to said frequency-modulated carrier.

Claim 10

Dependent Claim 60 words

A stereophonic sound transmission system as defined in claim 1 wherein said multiplex generator includes a pair of pre-emphasis networks for imposing pre-emphasis on respective ones of said left and right audio source signals, and wherein said demodulator means include a second pair of complementary de-emphasis networks for imposing compensating de-emphasis on said developed left and right audio source signals.

Claim 11

Dependent Claim 24 words

A stereophonic sound transmission system as defined in claim 9 wherein said pre-emphasis and de-emphasis networks have a time constant of approximately 25 microseconds.

Claim 12

Dependent Claim 39 words

A stereophonic sound transmission system as defined in claim 1 which further includes a pre-emphasis network disposed between said generator means and said transmitter means, and a complementary de-emphasis network disposed between said receiver means and said demodulator means.

Claim 13

Dependent Claim 21 words

A stereophonic sound transmission system as defined in claim 11 wherein said networks have a time constant of approximately 7.5 microseconds.

Claim 14

Dependent Claim 58 words

A stereophonic sound transmission system as defined in claim 12 wherein said generator means include circuit means for enhancing said second component by a factor of two with respect to said first component, and said demodulator means include complementary de-enhancement circuit means for enhancing said first component by a factor of two with respect to said second component.

Claim 15

Dependent Claim 52 words

A stereophonic sound transmission system as defined in claim 13 which further includes a pair of additional pre-emphasis networks between said left and right sources and said multiplex generator, and wherein said demodulator means include a pair of additional complementary de-emphasis networks for the left and right audio source signals developed therein.

Claim 16

Dependent Claim 21 words

A stereophonic sound transmission system as defined in claim 14 wherein said additional networks have a time constant of 25 microseconds.

Claim 17

Dependent Claim 37 words

A stereophonic sound transmission system as defined in claim 1 wherein said generator means include circuit means for enhancing said second component with respect to said first component, and said demodulator means include complementary deenhancement circuit means.

Claim 18

Dependent Claim 28 words

A stereophonic sound transmission system as defined in claim 16 wherein said second component is enhanced by a factor of 3 and deenhanced by a factor of 3.

Claim 19

Dependent Claim 98 words

A stereophonic sound transmission system as defined in claim 16 wherein said enhancement circuit means include first and second differential amplifiers, each having inverting and non-inverting input terminals, said left and right audio source signals being applied to said non-inverting terminals of said first and second amplifiers, respectively, and matrixing means comprising a first impedance connected between said inverting terminals, and second and third impedances connected between the outputs of said amplifiers to respective ones of said inverting terminals, said enhanced left and right audio source signals being developed at the outputs of respective ones of said amplifiers.

Claim 20

Dependent Claim 60 words

A stereophonic sound transmission system as defined in claim 16 wherein said deenhancement circuit means include first and second amplifiers, and matrixing means comprising first and second impedances serially connected between the left and right audio signals developed by said demodulator and the input terminals of respective ones of said amplifiers, and a third impedance connected between said input terminals.

Claim 21

Dependent Claim 52 words

A stereophonic sound transmission system as defined in claim 1 which further includes a pair of Dolby-B encoders coupled between said left and right audio sources and respective inputs of said multiplex generator, and a pair of Dolby-B decoders coupled to respective left and right audio source outputs of said demodulator means.

Claim 22

Dependent Claim 51 words

A stereophonic sound transmission system as defined in claim 20 which further includes a pair of pre-emphasis networks serially disposed with said Dolby-B encoders between said audio sources and said stereo generator, and a pair of de-emphasis networks serially disposed with said Dolby-B decoders at the output of said decoding means.

Claim 23

Dependent Claim 22 words

A stereophonic sound transmission system as defined in claim 21 wherein said pre-emphasis and de-emphasis networks have a 25 microsecond time constant.

Claim 24

Dependent Claim 60 words

A stereophonic sound transmission system as defined in claim 20 which further includes means for switching said Dolby-B encoders in and out of circuit, mode control means for adding a control signal component to said composite signal, and means responsive to said control effect associated with said receiver means for selectively switching said Dolby-B decoders in and out of circuit.

Claim 25

Dependent Claim 38 words

A stereophonic sound transmission system as defined in claim 23 wherein said left and right audio source signals each have a lower frequency limit, and said control signal component comprises a continuous-wave signal below said lower frequency limit.

Claim 26

Dependent Claim 56 words

A stereophonic sound transmission system as defined in claim 1 wherein said generator means include encoding means providing a transfer characteristic which increases the amplitude of low-level high frequency signals, the degree of increase decreasing with amplitude and increasing as a function of frequency, and said demodulator means include decoding circuit means having a complementary characteristic.

Claim 27

Dependent Claim 27 words

A stereophonic sound transmission system defined in claim 25 wherein said transfer characteristic substantially affects only signals above 20 KHz and extends substantially only to 53 KHz.

Claim 28

Dependent Claim 45 words

A stereophonic sound transmission system as defined in claim 2 wherein said left and right audio source signals have an upper limit of 15 KHz, said suppressed carrier is centered at 38 KHz, and said frequency-modulated signal has a maximum overall bandwidth of 106 KHz.

Claim 29

Independent Claim 198 words

The method of transmitting within a television broadcast channel having defined frequency limits left and right audio source signals and a video source signal each having a predetermined upper frequency limit, said video source signal being amplitude modulated on a video carrier to form an AM signal occupying a first portion of said channel, comprising the steps of: generating a composite signal including a first component representative of the sum of said left and right source signals, a second amplitude-modulated subcarrier component representative of the difference between said left and right signals, said subcarrier component having upper and lower sidebands centered about a suppressed subcarrier, and a pilot component having one-half the frequency of said suppressed subcarrier; generating an RF sound carrier in said broadcast channel having a predetermined frequency spacing from said video-modulated signal; modulating said sound carrier with said composite signal to form an FM signal occupying a second portion of said channel; conveying said video- and audio-modulated signals in said broadcast channel to a receiving location, and at said receiving location, developing said composite signal from said audiomodulated signal in said channel; and developing said left and right audio source signals from said composite signal.

Claim 30

Independent Claim 198 words

The method of transmitting within a television broadcast channel having defined frequency limits left and right audio source signals and a video source signal each having a predetermined upper frequency limit, said video source signal being amplitude modulated on a video carrier to form an AM signal occupying a first portion of said channel, comprising the steps of: generating a composite signal including a first component representative of the sum of said left and right source signals, a second amplitude-modulated subcarrier component representative of the difference between said left and right signals, said subcarrier component having upper and lower sidebands centered about a suppressed subcarrier, and a pilot component having one-half the frequency of said suppressed subcarrier; generating an RF sound carrier in said broadcast channel having a predetermined frequency spacing from said video-modulated signal; modulating said sound carrier with said composite signal to form an FM signal occupying a second portion of said channel; conveying said video- and audio-modulated signals in said broadcast channel to a receiving location, and at said receiving location, developing said composite signal from said audiomodulated signal in said channel; and developing said left and right audio source signals from said composite signal.

Claim 31

Dependent Claim 27 words

The method of transmitting stereophonic sound as defined in claim 28 wherein said sound carrier is separated from said video carrier in said channel by 4.5 MHz.

Claim 32

Dependent Claim 48 words

The method of transmitting stereophonic sound as defined in claim 28 wherein said video source signal has a predetermined horizontal scanning frequency, the frequency of said pilot component is 5/4 said horizontal scanning frequency, and the frequency of said subcarrier is twice the frequency of said pilot component.

Claim 33

Dependent Claim 38 words

The method of transmitting stereophonic sound as defined in claim 28 wherein said upper and lower sidebands each cause a maximum frequency deviation to said frequency-modulated carrier equal to one-half and maximum deviation caused by said first component.

Claim 34

Dependent Claim 51 words

The method of transmitting stereophonic sound as defined in claim 31 wherein said first component causes a maximum frequency deviation of 22.5 KHz to said frequency-modulated sound carrier and said upper and lower sidebands of said second component each cause a maximum frequency deviation of 11.25 KHz to said sound carrier.

Claim 35

Dependent Claim 46 words

The method of transmitting stereophonic sound as defined in claim 28 comprising the additional steps of: introducing pre-emphasis to said left and right audio source signals at the transmitter location, and introducing complementary de-emphasis to said developed left and right audio signals at said receiver location.

Claim 36

Dependent Claim 21 words

The method of transmitting stereophonic sound as defined in claim 33 wherein said pre-emphasis and de-emphasis have 25 microsecond time constants.

Claim 37

Dependent Claim 39 words

The method of transmitting stereophonic sound as defined in claim 28 which includes the further steps of: applying preemphasis to said composite signal at the transmitter location; and applying complementary deemphasis to said composite signal at the receiver location.

Claim 38

Dependent Claim 21 words

The method of transmitting stereophonic sound as defined in claim 35 wherein said preemphasis has a time constant of 7.5 microseconds.

Claim 39

Dependent Claim 52 words

The method of transmitting stereophonic sound as defined in claim 28 which includes the further steps of: enhancing the level of said component with respect to said first component at the transmitter location; and complementarily deenhancing the level of said second component with respect to said first component at the receiver location.

Claim 40

Dependent Claim 22 words

The method of transmitting stereophonic sound as defined in claim 37 wherein said second component is enhanced by a factor of 2.

Claim 41

Dependent Claim 49 words

The method of transmitting stereophonic sound as defined in claim 28 which includes the further steps of: applying Dolby-B type encoding to said left and right audio source signals at said transmitter; and applying complementary Dolby-B type decoding to said left and right audio output signals at said receiver.

Claim 42

Dependent Claim 68 words

The method of transmitting stereophonic sound as defined in claim 28 which includes the further steps of: increasing low-level high-frequency portions of said composite signal at the transmitter location, said increase having a magnitude increasing with frequency and decreasing with amplitude; and having an upper frequency limit substantially corresponding to said upper frequency limit of said L-R signal; and complementarily decreasing said composite signal at the receiver location.

Claim 43

Dependent Claim 27 words

The method of transmitting stereophonic sound as defined in claim 40 wherein only portions of said composite signal substantially between 20 KHz and 53 KHz are increased.

Claim 44

Dependent Claim 163 words

A receiver for receiving stereophonic sound transmissions included on a television broadcast channel of defined frequency limits, wherein said sound transmissions comprise a sound carrier frequency-modulated by a composite signal including a first component representative of the sum of the left and right source signals, a second amplitude modulated subcarrier component representative of the difference between the left and right signals, said subcarrier component having upper and lower sidebands centered about a suppressed subcarrier, and a pilot component having a frequency one-half the frequency of said suppressed carrier; said receiver comprising, in combination: tuner means for converting said television broadcast channel to an intermediate frequency channel including an intermediate frequency sound signal; sound bandpass filter means for separating said sound signal from said intermediate frequency channel; sound detector means for deriving from said intermediate frequency sound signal a composite signal including said first, second and third components; and stereo demodulator means for deriving said left and right source signals from said composite signal.

Claim 45

Dependent Claim 163 words

A receiver for receiving stereophonic sound transmissions included on a television broadcast channel of defined frequency limits, wherein said sound transmissions comprise a sound carrier frequency-modulated by a composite signal including a first component representative of the sum of the left and right source signals, a second amplitude modulated subcarrier component representative of the difference between the left and right signals, said subcarrier component having upper and lower sidebands centered about a suppressed subcarrier, and a pilot component having a frequency one-half the frequency of said suppressed carrier; said receiver comprising, in combination: tuner means for converting said television broadcast channel to an intermediate frequency channel including an intermediate frequency sound signal; sound bandpass filter means for separating said sound signal from said intermediate frequency channel; sound detector means for deriving from said intermediate frequency sound signal a composite signal including said first, second and third components; and stereo demodulator means for deriving said left and right source signals from said composite signal.

Claim 46

Dependent Claim 18 words

A receiver as defined in claim 42 wherein said intermediate frequency sound signal is centered at 10.7 MHz.

Claim 47

Dependent Claim 19 words

A receiver as defined in claim 42 wherein said tuner means comprise the tuner of an associated television receiver.

Claim 48

Dependent Claim 50 words

A receiver as defined in claim 42 which includes second conversion means comprising a mixer stage and a continuous wave oscillator, and wherein said intermediate frequency sound signal is converted by said conversion means to a second intermediate frequency and said sound intermediate frequency signal is applied to said detector.

Claim 49

Dependent Claim 23 words

A receiver as defined in claim 45 wherein said first intermediate frequency is 41.25 MHz and said second intermediate frequency is 10.7 MHz.

Claim 50

Dependent Claim 83 words

A receiver as defined in claim 42 wherein said intermediate frequency channel includes an intermediatefrequency video signal; and which further includes: video bandpass filter means for separating said video signal from said intermediate frequency channel; Fm detector means for deriving from said intermediate frequency video signal an output signal representative of frequency shift in said video signal; and matrixing means for combining said output signal with said first component of said composite signal to compensate for frequency shift in said intermediate frequency channel.

Claim 51

Dependent Claim 85 words

A receiver as defined in claim 47 which includes first and second mixer stages and wherein the output of said sound bandpass filter is applied to said first mixer stage to develop a sound signal at a second intermediate frequency, said sound signal being applied to said sound detector, and wherein the output of said video bandpass filter is applied to said second mixer stage to develop an intermediate frequency video signal, and said intermediate frequency video signal is applied to said FM detector means.

Claim 52

Dependent Claim 37 words

A receiver as defined in claim 48 which includes a continuous wave oscillator, the output of said oscillator being applied to said first and second mixer stages to develop said second intermediate frequency sound and video signals.

Claim 53

Dependent Claim 61 words

A receiver as defined in claim 49 wherein said first intermediate frequency video signal is centered at 45.75 MHz, said first intermediate frequency audio signal is centered at 41.25 MHz, said second intermediate frequency video signal is centered at 6.2 MHz, said second intermediate frequency sound signal is centered at 10.7 MHz, and the frequency of said oscillator is 51.95 MHz.

Claim 54

Dependent Claim 226 words

A television sound converter for receiving on an FM stereo broadcast receiver adapted to receive signals having a predetermined maximum deviation within a predetermined frequency range stereophonic sound transmissions included on a television broadcast channel of defined frequency limits, wherein said sound transmissions comprise a sound carrier frequency-modulated by a composite signal including a first component representative of the sum of the left and right source signals, a second amplitude-modulated subcarrier component representative of the difference between the left and right signals, said subcarrier component having upper and lower sidebands centered about a suppressed carrier, and a pilot component representative of the phase and frequency of the suppressed carrier; said converter comprising, in combination: tuner means for converting said television broadcast channel to an intermediate frequency channel including an intermediate frequency sound signal, said signal having a frequency comprising a predetermined fraction of a predetermined reception frequency within said predetermined frequency range, and having a maximum frequency deviation equal to said predetermined fraction of said predetermined maximum deviation of said receiver, where said fraction has a numerator of unity and a denominator of integer n; frequency multiplier means for multiplying the frequency of an applied signal by a factor of n; and means for applying said sound signal to said frequency multiplier means to obtain an RF output signal for application to said FM broadcast receiver.

Claim 55

Dependent Claim 226 words

A television sound converter for receiving on an FM stereo broadcast receiver adapted to receive signals having a predetermined maximum deviation within a predetermined frequency range stereophonic sound transmissions included on a television broadcast channel of defined frequency limits, wherein said sound transmissions comprise a sound carrier frequency-modulated by a composite signal including a first component representative of the sum of the left and right source signals, a second amplitude-modulated subcarrier component representative of the difference between the left and right signals, said subcarrier component having upper and lower sidebands centered about a suppressed carrier, and a pilot component representative of the phase and frequency of the suppressed carrier; said converter comprising, in combination: tuner means for converting said television broadcast channel to an intermediate frequency channel including an intermediate frequency sound signal, said signal having a frequency comprising a predetermined fraction of a predetermined reception frequency within said predetermined frequency range, and having a maximum frequency deviation equal to said predetermined fraction of said predetermined maximum deviation of said receiver, where said fraction has a numerator of unity and a denominator of integer n; frequency multiplier means for multiplying the frequency of an applied signal by a factor of n; and means for applying said sound signal to said frequency multiplier means to obtain an RF output signal for application to said FM broadcast receiver.

Claim 56

Dependent Claim 38 words

A television sound converter as defined in claim 51 wherein said predetermined fraction is 1/3, said predetermined maximum deviation of said receiver is 75 KHz, and said predetermined maximum deviation of said intermediate frequency signal is 25 KHz.

Claim 57

Dependent Claim 37 words

A television sound converter as defined in claim 52 wherein said intermediate frequency signal is centered at 30 MHz and tripled to 90 MHz by said frequency multiplier means for application to said FM stereo broadcast receiver.

Claim 58

Independent Claim 252 words

A system for simultaneously transmitting first and second audio program sources in conjunction with a video source signal modulated on an RF carrier on a television broadcast channel having defined frequency limits, said system comprising, in combination: generator means including a stereo multiplex generator for generating from left and right applied input signals a composite signal including a first component representative of the sum of said left and right signals, a second amplitude-modulated subcarrier component representative of the difference between said left and right signals, said subcarrier component having upper and lower sidebands centered about a suppressed subcarrier, and a pilot component representative of the phase and having one-half the frequency of said suppressed subcarrier; means for generating an RF sound carrier within said broadcast channel having a predetermined spacing from said video-modulated carrier, means for frequency-modulating said sound carrier with said composite signal; receiver means for receiving said television broadcast channel including means for deriving said composite signal; demodulator means for developing said first and second audio signals from said composite signal; first matrixing means associated with said generator means for combining said first and second audio program sources to form said left and right input signals whereby said first component of said composite signal conveys only said first program source and said second component of said composite signal conveys only said second program source; and second matrixing means associated with said demodulator means for combining said left and right audio signals to form said first and second program sources, respectively.

Claim 59

Independent Claim 252 words

A system for simultaneously transmitting first and second audio program sources in conjunction with a video source signal modulated on an RF carrier on a television broadcast channel having defined frequency limits, said system comprising, in combination: generator means including a stereo multiplex generator for generating from left and right applied input signals a composite signal including a first component representative of the sum of said left and right signals, a second amplitude-modulated subcarrier component representative of the difference between said left and right signals, said subcarrier component having upper and lower sidebands centered about a suppressed subcarrier, and a pilot component representative of the phase and having one-half the frequency of said suppressed subcarrier; means for generating an RF sound carrier within said broadcast channel having a predetermined spacing from said video-modulated carrier, means for frequency-modulating said sound carrier with said composite signal; receiver means for receiving said television broadcast channel including means for deriving said composite signal; demodulator means for developing said first and second audio signals from said composite signal; first matrixing means associated with said generator means for combining said first and second audio program sources to form said left and right input signals whereby said first component of said composite signal conveys only said first program source and said second component of said composite signal conveys only said second program source; and second matrixing means associated with said demodulator means for combining said left and right audio signals to form said first and second program sources, respectively.

Claim 60

Dependent Claim 89 words

A transmission system as defined in claim 54 wherein said first matrixing means comprise a pair of differential amplifiers; said first audio source being coupled through first and second impedances to the inverting imputs of said first and second amplifiers, respectively, and said second audio source being coupled through a third impedance to the inverting imput of said first amplifier and through a fourth impedance to the non-inverting imput of said second amplifier, the output of said first and second amplifiers comprising said left and right audio sources, respectively.

Claim 61

Dependent Claim 58 words

A transmission system as defined in claim 54 wherein said second matrixing means comprises a differential amplifier and left and right audio source means including a pair of impedances for coupling said source signals developed by said demodulator to the non-inverting and inverting imputs of said amplifier, the output of said amplifier comprising said second audio program source.

Claim 62

Dependent Claim 56 words

A transmission system as defined in claim 56 wherein said demodulator can be selectively operated in a monaural mode wherein the output of said demodulator comprises said first audio program source, and wherein user-actuable means are provided for conditioning said demodulator to operate in said monaural mode to obtain reception of said first audio program source.

Claim 63

Dependent Claim 23 words

A transmission system as defined in claim 54 wherein said first and second audio program sources comprise first and second different languages, respectively.

Claim 64

Dependent Claim 43 words

The method of transmitting stereophonic sound as defined in claim 28 wherein said left and right audio source signals have upper frequency limits of 15 KHz, said subcarrier component is centered at 38 KHz, and said pilot component is centered at 19 KHz.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1980-09-12	1981-03-14	1981-09-13	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1984-09-12	1985-03-14	1985-09-13	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1988-09-12	1989-03-14	1989-09-13	$7700.00	Window Closed / Lapsed

Stereophonic television sound transmission system

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