Multiplex decoding system

Claim 2

In a radio receiver for developing signals from a received transmission including a carrier wave modulated by a composite signal comprising at least a modulated suppressed subcarrier component and a pilot component having a predetermined time and frequency relationship with respect to said subcarrier, the combination comprising: oscillator means for providing a recurring wave having a fundamental frequency component; first means comprising first frequency dividing means coupled to said oscillator means for producing a first reference wave in predetermined time-frequency relation with said fundamental frequency component, the frequency of said first reference wave being (1/M) times said fundamental frequency component where M is an integer greater than unity; signal coupling means for coupling signals extending over substantially the entire frequency range of said composite signals; synchronous phase detection means coupled to said first means and direct coupled in a balanced manner to said signal coupling means for developing control signals representative of phase differences between said first reference wave and said pilot component; means coupled to said oscillator means and responsive to said control signals for varying the phase and frequency of said oscillator means to maintain said fundamental frequency component at a frequency equal to M times said pilot component frequency and to maintain said fundamental component in predetermined timed relation with respect to said pilot component; second means coupled to said oscillator means for producing at least a second reference wave having a predetermined timefrequency relationship with respect to said fundamental component different from that of said first reference wave; and additional synchronous detection means coupled at least to said second means and to said signal coupling means for detecting components of said composite signal synchronous at the frequency of said second reference wave.

Claim 3

The combination according to claim 1 wherein: said second means comprises second frequency dividing means for producing a second reference wave at a second frequency less than the frequency of said fundamental component.

Claim 4

The combination according to claim 1 wherein: said second reference wave is at a frequency equal to said subcarrier frequency; and said additional synchronous detection means is arranged for synchronously detecting the modulation information of said suppressed subcarrier component.

Claim 5

The combination according to claim 2 wherein: said phase detection means comprises a synchronous quadrature phase detector for producing control signals substantially free of amplitude modulation components of said pilot signal.

Claim 6

The combination according to claim 4 wherein: said synchronous quadrature phase detector comprises a sub-audio bandwidth output circuit for providing substantially noise-free control signals.

Claim 7

The combination according to claim 4 wherein: said multiple (M) is an Even integer greater than two; said suppressed subcarrier component includes amplitude modulation information corresponding to stereophonically related audio difference signals, and said synchronous modulation detection means is arranged to produce oppositely phased audio difference signals.

Claim 8

In a radio receiver for developing signals from a received transmission including a carrier wave modulated by a composite signal comprising at least a modulated suppressed subcarrier component and a pilot component having a predetermined time and frequency relationship with respect to said subcarrier, the combination comprising: oscillator means for providing a recurring wave having a fundamental frequency component; first means coupled to said oscillator means for producing a first reference wave in predetermined time-frequency relation with said fundamental frequency component, the frequency of said first reference wave being (1/M) times said fundamental frequency component where M is an integer; signal coupling means for coupling signals extending over substantially the entire frequency range of said composite signals; synchronous phase detection means coupled to said first means and to said signal coupling means for developing control signals representative of phase differences between said first reference wave and said pilot component; means coupled to said oscillator means and responsive to said control signals for varying the phase and frequency of said oscillator means to maintain said fundamental frequency component at a frequency equal to M times said pilot component frequency and to maintain said fundamental component in predetermined timed relation with respect to said pilot component; second means coupled to said oscillator means for producing at least a second reference wave having a frequency equal to the frequency of said pilot component and in quadrature phase relation with said first reference wave; and additional synchronous detection means coupled at least to said second means and to said signal coupling means for developing indications of presence in said composite signals of said pilot component.

Claim 9

In a radio receiver for developing signals from a received transmission including a carrier wave modulated by a composite signal comprising at least a modulated suppressed subcarrier component and a pilot component having a predetermined time and frequency relationship with respect to said subcarrier, the combination comprising: oscillator means for providing a recurring wave having a fundamental frequency component; first means coupled to said oscillator means for producing a first reference wave in predetermined time-frequency relation with said fundamental frequency component, the frequency of said first reference wave being (1/M) times said fundamental frequency component where M is an integer; signal coupling means for coupling signals extending over substantially the entire frequency range of said composite signals; synchronous phase detection means coupled to said first means and to said signal coupling means for developing control signals representative of phase differences between said first reference wave and said pilot component; means coupled to said oscillator means and responsive to said control signals for varying the phase and frequency of said oscillator means to maintain said fundamental frequency component at a frequency equal to M times said pilot component frequency and to maintain said fundamental component in predetermined timed relation with respect to said pilot component; second means coupled to said oscillator means for producing at least a second reference wave having a frequency equal to the frequency of said pilot component and in quadrature phase relation with said first reference wave; and additional synchronous detection means coupled at least to said second means and to said signal coupling means for developing indications of presence in said composite signals of said pilot component.

Claim 10

The combination according to claim 7 wherein: said first and second means comprise frequency dividing means for producing said first and second reference waves.

Claim 11

The combination according to claim 8 wherein: said first and second frequency dividing means comprise bistable counters coupled to said oscillator means for producing frequency divided outputs in fixed time relation with said fundamental frequency component.

Claim 12

In a radio receiver for developing signals from a received transmission including a carrier wave modulated by a composite signal comprising at least a modulated suppressed subcarrier component and a pilot component having a predetermined time and frequency relationship with respect to said subcarrier, the combination comprising: oscillator means for providing a recurring wave having a fundamental frequency component; first means coupled to said oscillator means for producing a first reference wave in predetermined time-frequency relation with said fundamental frequency component, the frequency of said first reference wave being (1/M) times said fundamental frequency component where M is an integer; signal coupling means for coupling signals extending over substantially the entire frequency range of said composite signals; synchronous phase detection means coupled to said first means and to said signal coupling means for developing control signals representative of phase differences between said first reference wave and said pilot component; means coupled to said oscillator means and responsive to said control signals for varying the phase and frequency of said oscillator means to maintain said fundamental frequency component at a frequency equal to M times said pilot component frequency and to maintain said fundamental component in predetermined timed relation with respect to said pilot component; second means coupled to said oscillator means for producing at least a second reference wave at a frequency greater than the highest signal component frequency of said composite signal; and additional synchronous detection means comprising noise detection means coupled at least to said second means and to said signal coupling means for developing indications of presence in said composite signal of above-band noise components.

Claim 13

In a radio receiver for developing signals from a received transmission including a carrier wave modulated by a composite signal comprising at least a modulated suppressed subcarrier component and a pilot component having a predetermined time and frequency relationship with respect to said subcarrier, the combination comprising: oscillator means for providing a recurring wave having a fundamental frequency component; first means coupled to said oscillator means for producing a first reference wave in predetermined time-frequency relation with said fundamental frequency component, the frequency of said first reference wave being (1/M) times said fundamental frequency component where M is an integer; signal coupling means for coupling signals extending over substantially the entire frequency range of said composite signals; synchronous phase detection means coupled to said first means and to said signal coupling means for developing control signals representative of phase differences between said first reference wave and said pilot component; means coupled to said oscillator means and responsive to said control signals for varying the phase and frequency of said oscillator means to maintain said fundamental frequency component at a frequency equal to M times said pilot component frequency and to maintain said fundamental component in predetermined timed relation with respect to said pilot component; second means coupled to said oscillator means for producing at least a second reference wave at a frequency greater than the highest signal component frequency of said composite signal; and additional synchronous detection means comprising noise detection means coupled at least to said second means and to said signal coupling means for developing indications of presence in said composite signal of above-band noise components.

Claim 14

The combination according to claim 10 wherein: said noise detection means comprises a source of threshold voltage representative of composite signal level, means for comparing detected above-band noise components to said threshold voltage and means for developing indications of singal-to-noise ratio below a predetermined acceptable limit.

Claim 15

The combination according to claim 11 wherein: said second means comprises means for developing a second reference wave at a frequency of the order of 100 KHz.

Claim 16

The combination according to claim 12 wherein: said first and second means comprise frequency dividing means coupled to said oscillator.

Claim 17

The combination according to claim 13 wherein: said first and second frequency dividing means comprise bistable counters coupled to said oscillator for producing frequency divided outputs in fixed time relation with said fundamental frequency component.

Claim 18

The combination according to claim 1 wherein: said second means comprises means for producing said second reference wave at a frequency equal to said subcarrier frequency, and said additional synchronous detection means is coupled to said second means and to said signal coupling means for synchronously detecting the modulation information of said suppressed subcarrier component.

Claim 19

The combination according to claim 15 wherein: said composite signal is a stereophonic frequency modulation composite signal further comprising an audio sum signal component and said suppressed subcarrier component is modulated with audio difference signals.

Claim 20

The combination according to claim 16 wherein: said additional synchronous detection means comprises signal matrixing means coupled to said signal coupling means for combining the detected modulation information of said suppressed subcarrier component and said sum signal component to produce stereophonically related audio signals.

Claim 21

The combination according to claim 17 wherein: said signal coupling means is direct coupled to said matrixing means.

Claim 22

In a radio receiver for developing signals from a received transmission including a carrier wave frequency modulated by a composite stereophonic signal comprising at least an audio sum signal component, a suppressed subcarrier component amplitude modulated by audio difference signals and a pilot component having a predetermined time and frequency relationship with respect to said subcarrier, the combination comprising: a controllable oscillator for providing a recurring wave having a fundamental frequency component equal to an even harmonic of said pilot signal; a plurality of bistable counters coupled to said oscillator including first frequency dividing means for producing a first reference wave in synchronism with said recurring wave and at a frequency equal to that of said pilot signal; signal coupling means for direct coupling signals extending over substantially the entire frequency range of said composite signals; synchronous phase detection means coupled to said first frequency dividing means and direct coupled in a balanced manner to said signal coupling means for developing control signals representative of deviations from quadrature phase relation between said first reference wave and said pilot signal; means coupled to said oscillator and responsive to said control signals for varying the phase and frequency of said oscillator to maintain said fundamental frequency componeNt at said even harmonic frequency and to maintain said quadrature phase relation between said first reference wave and pilot signals; said plurality of bistable counters further comprising second frequency dividing means for producing a second reference wave in synchronism with said first reference wave and at a frequency equal to that of said suppressed subcarrier; and additional synchronous detection means comprising at least a first synchronous detector coupled to said second frequency dividing means and to said signal coupling means for detecting said audio difference signals.

Claim 23

In a radio receiver for developing signals from a received transmission including a carrier wave frequency modulated by a composite stereophonic signal comprising at least an audio sum signal component, a suppressed subcarrier component amplitude modulated by audio difference signals and a pilot component having a predetermined time and frequency relationship with respect to said subcarrier, the combination comprising: a controllable oscillator for providing a recurring wave having a fundamental frequency component equal to an even harmonic of said pilot signal; a plurality of bistable counters coupled to said oscillator including first frequency dividing means for producing a first reference wave in synchronism with said recurring wave and at a frequency equal to that of said pilot signal; signal coupling means for direct coupling signals extending over substantially the entire frequency range of said composite signals; synchronous phase detection means coupled to said first frequency dividing means and direct coupled in a balanced manner to said signal coupling means for developing control signals representative of deviations from quadrature phase relation between said first reference wave and said pilot signal; means coupled to said oscillator and responsive to said control signals for varying the phase and frequency of said oscillator to maintain said fundamental frequency componeNt at said even harmonic frequency and to maintain said quadrature phase relation between said first reference wave and pilot signals; said plurality of bistable counters further comprising second frequency dividing means for producing a second reference wave in synchronism with said first reference wave and at a frequency equal to that of said suppressed subcarrier; and additional synchronous detection means comprising at least a first synchronous detector coupled to said second frequency dividing means and to said signal coupling means for detecting said audio difference signals.

Claim 24

In a radio receiver for developing signals from a received transmission including a carrier wave frequency modulated by a composite stereophonic signal comprising at least an audio sum signal component, a suppressed subcarrier component amplitude modulated by audio difference signals and a pilot component having a predetermined time and frequency relationship with respect to said subcarrier, the combination comprising: a controllable oscillator for providing a recurring wave having a fundamental frequency component equal to an even harmonic of said pilot signal; a plurality of bistable counters coupled to said oscillator including first frequency dividing means for producing a first reference wave in synchronism with said recurring wave and at a frequency equal to that of said pilot signal; signal coupling means for direct coupling signals extending over substantially the entire frequency range of said composite signal; synchronous phase detection means coupled to said first frequency dividing means and to said signal coupling means for developing control signals representative of deviations from quadrature phase relation between said first reference wave and said pilot signal; means coupled to said oscillator and responsive to said control signals for varying the phase and frequency of said oscillator to maintain said fundamental frequency component at said even harmonic frequency and to maintain said quadrature phase relation between said first reference wave and pilot signals; said plurality of bistable counters further comprising second frequency dividing means for producing a second reference wave in synchronism with said first reference wave and at a frequency equal to that of said suppressed subcarrier; additional synchronous detection means comprising at least a first synchronous detector coupled to said second frequency dividing means and to said signal coupling means for detecting said audio difference signals; said plurality of bistable counters further comprising fourth frequency dividing means for producing a fourth reference wave in synchronism with said recurring wave and at a frequency above the highest signal frequency of said composite signal; said additional synchronous detection means further comprising a third synchronous detector coupled to said fourth frequency dividing means and to said signal coupling means for producing indications of presence of above-band noise in said composite signals.

Claim 25

In a radio receiver for developing signals from a received transmission including a carrier wave frequency modulated by a composite stereophonic signal comprising at least an audio sum signal component, a suppressed subcarrier component amplitude modulated by audio difference signals and a pilot component having a predetermined time and frequency relationship with respect to said subcarrier, the combination comprising: a controllable oscillator for providing a recurring wave having a fundamental frequency component equal to an even harmonic of said pilot signal; a plurality of bistable counters coupled to said oscillator including first frequency dividing means for producing a first reference wave in synchronism with said recurring wave and at a frequency equal to that of said pilot signal; signal coupling means for direct coupling signals extending over substantially the entire frequency range of said composite signal; synchronous phase detection means coupled to said first frequency dividing means and to said signal coupling means for developing control signals representative of deviations from quadrature phase relation between said first reference wave and said pilot signal; means coupled to said oscillator and responsive to said control signals for varying the phase and frequency of said oscillator to maintain said fundamental frequency component at said even harmonic frequency and to maintain said quadrature phase relation between said first reference wave and pilot signals; said plurality of bistable counters further comprising second frequency dividing means for producing a second reference wave in synchronism with said first reference wave and at a frequency equal to that of said suppressed subcarrier; additional synchronous detection means comprising at least a first synchronous detector coupled to said second frequency dividing means and to said signal coupling means for detecting said audio difference signals; said plurality of bistable counters further comprising fourth frequency dividing means for producing a fourth reference wave in synchronism with said recurring wave and at a frequency above the highest signal frequency of said composite signal; said additional synchronous detection means further comprising a third synchronous detector coupled to said fourth frequency dividing means and to said signal coupling means for producing indications of presence of above-band noise in said composite signals.

Claim 26

In a radio receiver for developing signals from a received transmission including a carrier wave frequency modulated by a composite stereophonic signal comprising at least an audio sum signal component, a suppressed subcarrier component amplitude modulated by audio difference signals and a pilot component having a predetermined time and frequency relationship with respect to said subcarrier, the combination comprising: a controllable oscillator for providing a recurring wave having a fundamental frequency component equal to an even harmonic of said pilot signal; a plurality of bistable counters coupled to said oscillator including first frequency dividing means for producing a first reference wave in synchronism with said recurring wave and at a frequency equal to that of said pilot signal; signal coupling means for direct coupling signals extending over substantially the entire frequency range of said composite signals; synchronous phase detection means coupled to said first frequency dividing means and to said signal coupling means for developing control signals representative of deviations from quadrature phase relation between said first reference wave and said pilot signal; means coupled to said oscillator and responsive to said control signals for varying the phase and frequency of said oscillator to maintain said fundamental frequency component at said even harmonic frequency and to maintain said quadrature phase relation between said first reference wave and pilot signals; said plurality of bistable counters further comprising second frequency dividing means for producing a second reference wave in synchronism with said first reference wave and at a frequency equal to that of said suppressed subcarrier; and additional synchronous detection means comprising at least a first synchronous detector coupled to said second frequency dividing means and to said signal coupling means for detecting said audio difference signals; said plurality of bistable counters further comprising third frequency dividing means for producing a third reference wave in synchronism with said recurring wave, at a frequency equal to that of said pilot signal and in quadrature phase relationship with said first reference wave; said additional synchronous detection means further comprising a second synchronous detector coupled to said third frequency dividing means and to said signal coupling means for producing indications of the presence of said pilot component.

Claim 27

In a radio receiver for developing signals from a received transmission including a carrier wave frequency modulated by a composite stereophonic signal comprising at least an audio sum signal component, a suppressed subcarrier component amplitude modulated by audio difference signals and a pilot component having a predetermined time and frequency relationship with respect to said subcarrier, the combination comprising: a controllable oscillator for providing a recurring wave having a fundamental frequency component equal to an even harmonic of said pilot signal; a plurality of bistable counters coupled to said oscillator including first frequency dividing means for producing a first reference wave in synchronism with said recurring wave and at a frequency equal to that of said pilot signal; signal coupling means for direct coupling signals extending over substantially the entire frequency range of said composite signals; synchronous phase detection means coupled to said first frequency dividing means and to said signal coupling means for developing control signals representative of deviations from quadrature phase relation between said first reference wave and said pilot signal; means coupled to said oscillator and responsive to said control signals for varying the phase and frequency of said oscillator to maintain said fundamental frequency component at said even harmonic frequency and to maintain said quadrature phase relation between said first reference wave and pilot signals; said plurality of bistable counters further comprising second frequency dividing means for producing a second reference wave in synchronism with said first reference wave and at a frequency equal to that of said suppressed subcarrier; and additional synchronous detection means comprising at least a first synchronous detector coupled to said second frequency dividing means and to said signal coupling means for detecting said audio difference signals; said plurality of bistable counters further comprising third frequency dividing means for producing a third reference wave in synchronism with said recurring wave, at a frequency equal to that of said pilot signal and in quadrature phase relationship with said first reference wave; said additional synchronous detection means further comprising a second synchronous detector coupled to said third frequency dividing means and to said signal coupling means for producing indications of the presence of said pilot component.

Claim 28

The combination according to claim 21 wherein: said additional synchronous detection means further comprises switching means coupled to said second synchronous detector for enabling operation of said first synchronous detector in response to indications of presence of said pilot component and for disabling operation thereof in the absence of said pilot component.

Claim 29

The combination according to claim 21 wherein: said plurality of bistable counters further comprises fourth frequency dividing means for producing a fourth reference wave in synchronism with said recurring wave and at a frequency above the highest signal frequency of said composite signal; said additional synchronous detection means further comprising a third synchronous detector coupled to said fourth frequency dividing means and to said signal coupling means for producing indications of presence of above-band noise in said composite signals.

Claim 30

The combination according to claim 23 wherein: said first synchronous detector further comprises switching means coupled to said second and third synchronous detectors for enabling operation of said first synchronous detector in response to indications of presence of said pilot component and absence of unacceptable noise components and for disabling operation of said first detector in the absence of said pilot component or the presence of unacceptable noise components.

Claim 31

The combination according to claim 21 wherein: said bistable counters are direct coupled to said oscillator and to said synchronous detection means.

Claim 32

The combination according to claim 25 wherein: said signal coupling means are direct coupled to said synchronous detection means.

Claim 33

The combination according to claim 19 and further comprising: signal matrixing means coupled to said signal coupling means and to said first synchronous detector for developing stereophonically related audio signals.

Claim 34

The combination according to claim 27 wherein: said signal coupling means is direct coupled to said first synchronous detector and to said signal matrixing means.

Claim 35

The combination according to claim 28 wherein: said bistable counters are direct coupled to said oscillator and to said synchronous detection means.

Claim 36

In a radio receiver for developing signals from a received transmission including a carrier wave modulated by a composite signal comPrising at least a modulated suppressed subcarrier component and a pilot component having a predetermined time and frequency relationship with respect to said subcarrier, the combination comprising: oscillator means for providing a recurring wave having a fundamental frequency component; frequency dividing means comprising bistable counter means coupled to said oscillator means for producing a reference wave in timed relation with and at a submultiple (1/M) of said fundamental frequency component, where M is an integer greater than one; signal coupling means for coupling signals extending over substantially the entire frequency range of said composite signals; synchronous phase detection means coupled to said frequency dividing means and direct coupled in a balanced manner to said signal coupling means for developing control signals representative of phase differences between said reference wave and said pilot component, and means coupled to said oscillator means and responsive to said control signals for varying the phase and frequency of said oscillator means to maintain said fundamental frequency component at a frequency equal to M times said pilot component frequency and to maintain said recurring wave in predetermined timed relation with respect to said pilot component.

Claim 37

In a radio receiver for developing signals from a received transmission including a carrier wave modulated by a composite signal comPrising at least a modulated suppressed subcarrier component and a pilot component having a predetermined time and frequency relationship with respect to said subcarrier, the combination comprising: oscillator means for providing a recurring wave having a fundamental frequency component; frequency dividing means comprising bistable counter means coupled to said oscillator means for producing a reference wave in timed relation with and at a submultiple (1/M) of said fundamental frequency component, where M is an integer greater than one; signal coupling means for coupling signals extending over substantially the entire frequency range of said composite signals; synchronous phase detection means coupled to said frequency dividing means and direct coupled in a balanced manner to said signal coupling means for developing control signals representative of phase differences between said reference wave and said pilot component, and means coupled to said oscillator means and responsive to said control signals for varying the phase and frequency of said oscillator means to maintain said fundamental frequency component at a frequency equal to M times said pilot component frequency and to maintain said recurring wave in predetermined timed relation with respect to said pilot component.

Claim 38

The combination according to claim 30 wherein: said synchronous phase detection means is arranged to develop control signals representative of deviations from quadrature phase relationship between said reference and pilot components.

Claim 39

The combination according to claim 31 wherein: said integer M is selected such that the frequencies of said reference wave and pilot component are substantially equal.

Claim 40

The combination according to claim 32 wherein: said composite signal comprises a stereophonic composite signal further including audio sum signals and said suppressed subcarrier component includes audio difference signal information; said signal coupling means being arranged to couple signals extending over a frequency range of at least 0 to 53 KHz.

Claim 41

The combination according to claim 33 wherein: M is an even integer.