Decoder apparatus with logic circuit for use with a four channel stereo

Claim 2

Four channel stereo system decoder apparatus for converting first and second composite signals LT and RT respectively containing, dominant left-front (LF) aand right-front (RF) signal components, each including side-effect left-back (LB) and rightback (RB) signal components, if present, and wherein the LB signal components have substantially equal magnitudes and are in substantially quadrature relationship with each other in the LT and RT composite signals and the LB signal component in one of the LT and RT composite signals is in leading relationship with the LB component in the other of the LT and RT composite signals and wherein the RB signal components have substantially equal magnitudes and are in substantially quadrature relationship with each other in the LT and RT composite signals and the RB signal component in one of the LT and RT composite signals is in lagging relationship with the RB signal component in the other of the LT and RT composite signals, into four separate output signals designated as first, second, third and fourth output signals, respectively predominantly containing LF, RF, LB and RBsignal components, respectively, the apparatus comprising in combination: a decoding matrix having first and second input terminals to which the LT and RT composite signals are respectively applied, first, second, third and fourth output terminals at which the first, second, third and fourth output signals appear; a plurality of phase-shifting networks and a plurality of combining networks connected to each other between the input terminals and the output terminals and being operative to transfer substantially equal amounts of LF, RF, LB and RB signal components as dominant signals in phase with each other to the first, second, third and fourth output terminals, respectively, the LF and RF dominant signals each being accompanied by lower amplitude, quadrature related LB and RB signal components with the LB components accompanying each one of the dominant LF and RF signals being in phase opposition to the RB components accompanying the other of the dominant LF and RF signals and the LB and RB dominant signals each being accompanied by lower amplitude, quadrature related LF and RF signal components with the LF signal components accompanying each one of the dominant LB and RB signals being in phase opposition to the RF signal components accompanying the other of the LB and RB signals; first, second, third and fourth variable transmission means connected to the first, second, third and fourth output terminals, respectively, of the decoding matrix; first logic means having first, second, third and fourth input terminals connected to the first, second, third and fourth output terminals, respectively, of the decoding matrix, the first logic means including first, second, third and fourth rectifiers for full wave rectifying the signals appearing at the first, second, third and fourth input terminals of the first logic means, respectively, first subtracting means for subtracting the second rectified signal from the first rectified signal to produce a first difference signal, second subtracting means for subtracting the fourth rectified signal from the third rectified signal to produce a second difference signal and first comparing means for comparing the magnitudes of the first and second difference signals to produce first and second control signals; second logic means having means for receiving the signals applied to the first and second input terminals of the first logic means, combining means for combining the signals received by the second logic means, third subtracting means for subtracting the signal received from the second input terminal of the first logic means from the signal received from the first input terminal of the first logic means, fifth and sixth rectifiers for full wave rectifying the output signals derived from the combining means and the third subtracting means, respectively, and second comparing means for comparing the magnitudes of the output signals derived from the fifth and sixth rectifying means and for producing third and fourth control signals; and means for selectively applying the first, second, third and fourth control signals to the first, second, third and fourth variable transmission means to substantially eliminate crosstalk signal components from the signals transmitted by said first, second, third and fourth variable transmission means.

Claim 3

A multisignal decoding aparatus comprising matrix means for receiving first and second composite signals LT and RT, respectively, containing dominant left-front (LF) and right-front (RF) signal components and each including Subdominant left-back (LB) and right back (RB) signal components, the LB signal components having substantially equal magnitudes and the LB signal component in the LT signal being in substantially lagging quadrature relationship with the LB signal component in the RT signal, the RB signal components having substantially equal magnitude and the RB signal component in the LT signal being in substantially leading quadrature relationship with the RB signal component in the RT signal; the composite LT and RT signals further being converted by the matrix means into first, second, third and fourth separate output signals predominantly containing LF, RF, LB and RB signal components, respectively, the first and second output signals containing subdominant signal components of the LB and RB signal which are in quadrature relationship with each other, the LB signal component in each one of the first and second output signals being in phase opposition to the RB signal component in the other of the first and second output signals, the third and fourth output signals containing subdominant lower amplitude, quadrature related LF and RF signal components, the LF signal component in each one of the third and fourth output signals being in phase opposition to the RF signal component in the other of the third and fourth output signals; first, second, third and fourth variable transmission means each having separate input and output terminals; first, wavematching logic means including first, second, third and fourth input terminals; means for supplying the first, second, third and fourth output signals to the inputs of both the first, second, third and fourth variable transmission means and the first, second, third and fourth input terminals of the first logic means, respectively; the first logic means further including means for separately rectifying the first, second, third and fourth signals applied to the corresponding input terminals of the first logic means, means for subtracting the second rectified input signal from the first rectified input signal to produce a first difference signal and for subtracting the fourth rectified input signal from the third rectified input signal to produce a second difference signal, and means for comparing the magnitudes of the first and second difference signals for producing first and second control signals of opposite polarities; second, front-back logic means including means for producing signals representative of the sum and difference of the signals applied to the first and second input terminals of the first logic means, and means for comparing the magnitudes of these sum and difference signals to produce third and fourth control signals of opposite polarities; means for combining the first and third control signals to simultaneously control the transmissive characteristics of the first and second variable transmission means; means for combining the second and fourth control signals to simultaneously control the transmissive characteristics of the third and fourth variable transmission means; means responsive to the third control signal for mixing the outputs of the third and fourth variable transmission means and means responsive to the fourth control signal for mixing the outputs of the first and second variable transmission means.

Claim 4

A multisignal decoding aparatus comprising matrix means for receiving first and second composite signals LT and RT, respectively, containing dominant left-front (LF) and right-front (RF) signal components and each including Subdominant left-back (LB) and right back (RB) signal components, the LB signal components having substantially equal magnitudes and the LB signal component in the LT signal being in substantially lagging quadrature relationship with the LB signal component in the RT signal, the RB signal components having substantially equal magnitude and the RB signal component in the LT signal being in substantially leading quadrature relationship with the RB signal component in the RT signal; the composite LT and RT signals further being converted by the matrix means into first, second, third and fourth separate output signals predominantly containing LF, RF, LB and RB signal components, respectively, the first and second output signals containing subdominant signal components of the LB and RB signal which are in quadrature relationship with each other, the LB signal component in each one of the first and second output signals being in phase opposition to the RB signal component in the other of the first and second output signals, the third and fourth output signals containing subdominant lower amplitude, quadrature related LF and RF signal components, the LF signal component in each one of the third and fourth output signals being in phase opposition to the RF signal component in the other of the third and fourth output signals; first, second, third and fourth variable transmission means each having separate input and output terminals; first, wavematching logic means including first, second, third and fourth input terminals; means for supplying the first, second, third and fourth output signals to the inputs of both the first, second, third and fourth variable transmission means and the first, second, third and fourth input terminals of the first logic means, respectively; the first logic means further including means for separately rectifying the first, second, third and fourth signals applied to the corresponding input terminals of the first logic means, means for subtracting the second rectified input signal from the first rectified input signal to produce a first difference signal and for subtracting the fourth rectified input signal from the third rectified input signal to produce a second difference signal, and means for comparing the magnitudes of the first and second difference signals for producing first and second control signals of opposite polarities; second, front-back logic means including means for producing signals representative of the sum and difference of the signals applied to the first and second input terminals of the first logic means, and means for comparing the magnitudes of these sum and difference signals to produce third and fourth control signals of opposite polarities; means for combining the first and third control signals to simultaneously control the transmissive characteristics of the first and second variable transmission means; means for combining the second and fourth control signals to simultaneously control the transmissive characteristics of the third and fourth variable transmission means; means responsive to the third control signal for mixing the outputs of the third and fourth variable transmission means and means responsive to the fourth control signal for mixing the outputs of the first and second variable transmission means.

Claim 5

A multisignal decoding apparatus as recited in claim 2 wherein the first, second, third and fourth variable transmission means comprise variable gain amplifiers whose gains are controlled by the respective control signals.

Claim 6

In combination with apparatus for decoding two channels of audio information embodied in LT and RT composite signals, respectively, the LT signal containing a left-front signal (LF) having a predetermined amplitude and a zero reFerence phase, a left-back signal (LB) having a -3dB relative amplitude and -90* relative phase, and a right-back signal (RB) having a -3dB relative amplitude and a zero reference phase; the RT signal containing a right-front signal (RF) having a predetermined amplitude and a zero reference phase, a right-back signal (RB) having a -3dB relative amplitude and a +90* relative phase and a left-back signal (LB) having a -3dB relative amplitude and a 180* relative phase, the decoding apparatus including phase shift matrixing means for converting LT and RT composite signals into first, second, third and fourth output signals having predominant signal components of LF, RF, LB and RB, respectively, each at a zero relative phase angle, the first output signal further containing a -3dB RB signal component at zero relative phase and a -3dB LB signal component at -90* relative phase, the second output signal containing a -3dB RB signal component at +90* relative phase and a -3dB LB signal component at 180* relative phase, the third output signal containing a -3dB LF signal component at +90* and a -3dB RF signal component at 180* relative phase, and the fourth output signal containing a -3dB LF signal component at 0* relative phase and a -3dB RF signal component at -90* relative phase; first, second, third and fourth variable gain amplifiers whose inputs are supplied with the first, second, third and fourth output signals of the phase shift matrixing means; first logic means having first, second, third and fourth input terminals, means for supplying the first, second, third and fourth output signals from the phase shift matrixing means to the first, second, third and fourth input terminals of the first logic means, respectively, first, second, third and fourth rectifying means connected to the first, second, third and fourth input terminals, respectively, of the first logic means for full wave rectifying the respective output signals supplied to the first logic means, first differencing means for subtracting the full wave rectified second output signal from the full wave rectified first output signal to produce a first difference signal, second differencing means for subtracting the full wave rectified fourth output signal from the full wave rectified third output signal to produce a second difference signal, fifth means for full wave rectifying the first difference signal, sixth means for full wave rectifying the second difference signal, differential amplifier means for comparing the magnitudes of the full wave rectified second difference signal with the full wave rectified first difference signal to produce first and second control signals having opposite polarities; second logic means having fifth and sixth input terminals connected to the first and second input terminals of the first logic means, respectively, first summing means for combining the signals applied to the fifth and sixth input terminals to produce a first sum signal, third differencing means for subtracting the signal applied to the sixth input terminal from the signal applied to the fifth input terminal of the second logic means to produce a third difference signal, seventh full wave rectifying means for full wave rectifying the first sum signal, eight full wave rectifying means for full wave rectifying the third difference signal, second differential amplifier means for comparing the magnitude of the first full wave rectified sum signal with the magnitude of the third full wave rectified difference signal to produce third and fourth control signals having opposite polarities; means for adding the third control signal to the first control signal to produce a fifth control signal, means for supplying the fifth control signal to simultaneously control the gains of the first and second variable gain amplifiers, means for combining the fourth control signal with the second control signal to produce a sixth control signal, means for supplying the sixth control signal to simultaneously control the gains of the third and fourth variable gain amplifiers; first mixing means responsive to the fourth control signal and connected between the outputs of the first and second variable gain amplifiers, and second mixing means responsive to the third control signal and connected between the outputs of the third and fourth variable gain amplifiers.

Claim 7

In combination with apparatus for decoding two channels of audio information embodied in LT and RT composite signals, respectively, the LT signal containing a left-front signal (LF) having a predetermined amplitude and a zero reFerence phase, a left-back signal (LB) having a -3dB relative amplitude and -90* relative phase, and a right-back signal (RB) having a -3dB relative amplitude and a zero reference phase; the RT signal containing a right-front signal (RF) having a predetermined amplitude and a zero reference phase, a right-back signal (RB) having a -3dB relative amplitude and a +90* relative phase and a left-back signal (LB) having a -3dB relative amplitude and a 180* relative phase, the decoding apparatus including phase shift matrixing means for converting LT and RT composite signals into first, second, third and fourth output signals having predominant signal components of LF, RF, LB and RB, respectively, each at a zero relative phase angle, the first output signal further containing a -3dB RB signal component at zero relative phase and a -3dB LB signal component at -90* relative phase, the second output signal containing a -3dB RB signal component at +90* relative phase and a -3dB LB signal component at 180* relative phase, the third output signal containing a -3dB LF signal component at +90* and a -3dB RF signal component at 180* relative phase, and the fourth output signal containing a -3dB LF signal component at 0* relative phase and a -3dB RF signal component at -90* relative phase; first, second, third and fourth variable gain amplifiers whose inputs are supplied with the first, second, third and fourth output signals of the phase shift matrixing means; first logic means having first, second, third and fourth input terminals, means for supplying the first, second, third and fourth output signals from the phase shift matrixing means to the first, second, third and fourth input terminals of the first logic means, respectively, first, second, third and fourth rectifying means connected to the first, second, third and fourth input terminals, respectively, of the first logic means for full wave rectifying the respective output signals supplied to the first logic means, first differencing means for subtracting the full wave rectified second output signal from the full wave rectified first output signal to produce a first difference signal, second differencing means for subtracting the full wave rectified fourth output signal from the full wave rectified third output signal to produce a second difference signal, fifth means for full wave rectifying the first difference signal, sixth means for full wave rectifying the second difference signal, differential amplifier means for comparing the magnitudes of the full wave rectified second difference signal with the full wave rectified first difference signal to produce first and second control signals having opposite polarities; second logic means having fifth and sixth input terminals connected to the first and second input terminals of the first logic means, respectively, first summing means for combining the signals applied to the fifth and sixth input terminals to produce a first sum signal, third differencing means for subtracting the signal applied to the sixth input terminal from the signal applied to the fifth input terminal of the second logic means to produce a third difference signal, seventh full wave rectifying means for full wave rectifying the first sum signal, eight full wave rectifying means for full wave rectifying the third difference signal, second differential amplifier means for comparing the magnitude of the first full wave rectified sum signal with the magnitude of the third full wave rectified difference signal to produce third and fourth control signals having opposite polarities; means for adding the third control signal to the first control signal to produce a fifth control signal, means for supplying the fifth control signal to simultaneously control the gains of the first and second variable gain amplifiers, means for combining the fourth control signal with the second control signal to produce a sixth control signal, means for supplying the sixth control signal to simultaneously control the gains of the third and fourth variable gain amplifiers; first mixing means responsive to the fourth control signal and connected between the outputs of the first and second variable gain amplifiers, and second mixing means responsive to the third control signal and connected between the outputs of the third and fourth variable gain amplifiers.

Claim 8

The combination as recited in claim 4 further comprising fifth, sixth, seventh and eighth variable gain amplifiers interposed between the first, second, third and fourth input terminals of the first logic means and the first, second, third and fourth output terminals of the phase shift matrixing means, respectively, second summing means supplied with the outputs of the first, second, third and fourth full wave rectifying means to produce a combined seventh control signal for simultaneously controlling the gains of the fifth, sixth, seventh and eighth variable gain amplifiers.

Claim 9

The apparatus as recited in claim 4 wherein the phase shift matrixing means is manufactured as a first integrated circuit and the first and second logic means are manufactured as a second combined integrated circuit.

Claim 10

The combination as recited in claim 4 wherein the first and second mixing means comprise field effect transistors whose source and drain electrodes are connected to the respective outputs of the variable gain amplifiers and whose gate electrodes are supplied with the respective fifth and sixth control signals.

Claim 11

The combination as recited in claim 4 wherein first, second, third and fourth means are provided for audibly reproducing the outputs of the first, second, third and fourth variable gain amplifiers, respectively, at left-front, right-front, left-back and right-back positions, respectively, of a listening area.