US3925615A - Multi-channel sound signal generating and reproducing circuits - Google Patents

Multi-channel sound signal generating and reproducing circuits Download PDF

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Publication number
US3925615A
US3925615A US335741A US33574173A US3925615A US 3925615 A US3925615 A US 3925615A US 335741 A US335741 A US 335741A US 33574173 A US33574173 A US 33574173A US 3925615 A US3925615 A US 3925615A
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output
phase
circuit means
arithmetic circuit
phase shifter
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Yasuaki Nakano
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Hitachi Ltd
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Hitachi Ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04S—STEREOPHONIC SYSTEMS 
    • H04S3/00—Systems employing more than two channels, e.g. quadraphonic
    • H04S3/02—Systems employing more than two channels, e.g. quadraphonic of the matrix type, i.e. in which input signals are combined algebraically, e.g. after having been phase shifted with respect to each other

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  • ABSTRACT An arrangement of a multi-channel sound circuit wherein a plurality of original electric signals produced from a plurality of sources of sound signals as arranged on a plane are converted into a plurality of transmission channel signals by means of a matrix circuit which shifts the phases of the electric signals by amounts proportional to the azimuths of the sound signals, respectively, and which adds the electric signals, and wherein the original sound signals are reproduced from the transmission channel signals by means of a circuit whichhasthe same arrangement as the matrix circuit, said matrix circuit involving a plurality of factor matrices, and having an element 1 in each matrix formed of a first phase shifter circuit and an element neither 1 nor 0 formed of a second phase shifter circuit, the phase difference between the first and second phase shifter circuits being made a predetermined value, whereby the matrix circuit is arranged simply and economically.
  • the present invention relates to improvements in multi-channel sound signal generating and reproducing circuits. More particularly, it relates to improvements in multi-channel sound signal generating and reproducing circuits in a system in which a plurality of arrayed original sound signals are combined to transmit them by a plurality of transmission channels or to record them in a plurality of recording channels, and the original sound signals are reproduced from the transmitted or recorded signals.
  • the system (hereinafter termed the universal matrix system") is excellent in its compatibility with monophonic and biphonic systems, and is a hopeful method.
  • Theequation of a matrix is a square matrix of the same number of order as the number of sound sources.
  • the elements of the matrix are represented by r (where 7- denotes the minimum angle of the azimuths of the sound sources, and i andj rows and columns, respectively).
  • the four signal sources (forexample, electric signals obtained from microphones) arranged in such manner thattheir azimuths on a plane are spaced by every 90, are represented by S S S and S
  • the signals of the four signal sources are compounded according to the following equation, to make 4-channel signals, and then, they are sent to recording channels of a recording medium such as a phonograph record or to transmission lines for broadcasting or the like (hereinbelow, generically termed the transmission channels).
  • 'r is a symbol representative of a phase shift of 90.
  • 1' represents a phase shift of 180, 1 one of 270, Eq. (1) is calculated in conformity with the usual rules of arithmetics of vector and matrix.
  • the original signals are restored from the four transmitted or recorded signals T T T and T in accordance with:
  • 'r signifies a phase shift ofnamely, one of 270.
  • F 1*, 7 signify phase shifts of- 180, 270, 360, respectively.
  • Eq. 1 The procedure of Eq. 1 is considered to be coding, and that of Eq. 2 decoding (herein, however, pulse coding as in PCM is not meant). If the coding, transmission and decoding are perfectly performed, there holds:
  • the universal matrix system provides the reproduced signals of 4 channels with the identical restoration matrix in any of the cases where the numbers of the transmission lines are l, 2, 3 and 4.
  • the azimuth angles of the reproduced sounds are sharper as the number of the transmission lines is larger. For example, in the case of 8 channels, the azimuth is as sharp as 45, and in case of 16 channels, it is as sharp as 225. This feature is advantageous in building up a reproduction system.
  • phase shifter circuits In particular, the arrangement of phase shifter circuits is complicated in such circuits. It is therefore required to lessen the number of the phase shifter circuits as far as possible.
  • the principal object of the present invention is to simplify the arrangement of multi-channel sound signal generating and reproducing circuits according to the universal matrix system.
  • Another object of the present invention is to bring into simple arrangements, matrix circuits of the aforesaid muli-channel sound signal generating and reproducing circuits of the universal matrix system.
  • Still another object of the present invention is to reduce the number of phase shifters constituting the matrix circuits.
  • the present invention is constructed such that a matrix providing a multichannel sound signal generating or reproducing circuit is factorized on the basis ofthe periodicity of the matrix in the universal matrix system, that the factorized matrix is put into circuit components or contituents, and that they are connected in cascade.
  • FIG. 1 is a block diagram showing the construction of the universal matrix system
  • FIG. 2 is a connection diagram of a prior-art matrix circuit of a 4-channel sound signal reproducing circuit in the universal matrix system
  • FIGS. 3 and 4 are connection diagrams each showing an embodiment of a matrix circuit for use in a 4-channel sound signal generating circuit according to the present invention
  • FIG. 1 is a block diagram showing the construction of the universal matrix system to which the present invention is applied, and particularly illustrates 4-channel sound signal generating and reproducing circuits.
  • four signal sources such as microphones, 2a 2d are provided for a sound source 1 in such manner that the azimuths are spaced by every Output signals sent out from the signal sources are represented by S S S and S respectively.
  • the respective signal outputs are transformed into 4-channel signals.
  • T T,, T T by means of a 4-channel sound signal generating circuit or coding circuit 3.
  • the transformed signals are sent out to recording channels of a recording medium such as a sound recording disc, or transmission lines for broadcasting or the like (hereinafter generically called the transmission channels") 4.
  • Outputs from the transmission channels 4 are reproduced into signals P P P and P by means of a 4- channel sound signal reproducing circuit or decoding circuit 5.
  • the reproduced signals are converted into sound signals by means of four electroacoustic transducers, such as speakers, 7a 7d which are respectively arranged around a listener 6.
  • the number of the transmission channels 4 is not necessarily required to be four, but a sound effect as in the case of four channels is achieved even with two or three chan nels be appropriately constructing the coding circuit 3 and the decoding circuit 5.
  • the relations of Eqs. l. 2 and 3 as previously stated. apply to the signals S S T T and P P
  • FIG. 2 shows a prior-art circuit of the 4-channel sound signal reproducing circuit 5 as constructed on the basis of Eq. 2. If the signals T T,. T and T are changed into: S 5,. S and S in the circuit. respectively. the 4-channel sound signal generating circuit 3 will be constituted.
  • the signals T, T derived from the transmission channel 4 are applied to input terminals 80. 8h. 80 and 8d.
  • T and T are fed to adders 10a and via phase shifter circuits A including 9a2. 9u4 and 94'2. 904 and to adders I0! and I011 via phase shifter circuits B including 9h2.
  • phase shifter circuits B (with marks O) and the phase shifter circuits B (with marks O) have a phase difference of 90 therebe'tween.
  • the amplitude-versusfrequency characteristics of the respective phase shifters are as flat as possible.
  • the adders a to 10d effect the matrix operation of Eq. (2' and send out output signals to output terminals 4a to 4d, respectively.
  • the 16 phase shifter circuits are used in total as the phase shifter circuits A and B.
  • phase shifters are complicated in construction or circuit arrangement. Unless, in particular, the accuracy of phase shift is made as high as possible, the operation of the aforesaid matrix cannot be conducted precisely, and an error in the restoring circuit 5 and one in the coding circuit 3 will be superposed.
  • FIG. 3 and FIG. 4 show embodiments of the matrix circuits according to the present invention as constitute the 4-channel sound signal reproducing circuit in the universal matrix system.
  • the transmission channel signals T T T and T in FIGS. 3 and 4 are replaced with the sound source signals S 8,, S2 and S the 4-channel sound signal generating circuit 3 will be provided on the ground of Eq. 2 Eq. 2 and the relations of 1' representative of the phase shift of 90 and F representative of that of 90.
  • the 4-channel sound signal reproducing circuit will be described hereunder, the 4-channel sound signal generating circuit is of quite the same construction.
  • an input unit 12 is a phonograph pickup in case of the reproduction ofa disc, and a receiving set in case of the reception of broadcasting.
  • the input device 12 receives the 4-channel transmission signals, and delivers the signals T T T and T of Eq. 2 from output terminals 13a 13d. Since some vector components are replaced in Eq. 2, connections are crossed in the illustration of FIG. 3.
  • the signals T T transmitted from the input device 12 are applied to adders 14a 14d in such manner that two of them are combined as shown. Outputs of the adders 14a 14d are equivalent to multiplications of the vectors by the second one of the factorized matrices on the right of Eq. 4'. Subsequently, the outputs of the adders 14a are respectively applied to phase shifter circuits A at 15a 150, while the output of the adder 14d is applied to a phase shifter circuit B at 15d. As shown in the figure, outputs of the phase shifter circuits are applied to adders 16a 16d with two of them combined. In this case, the adders 16a 16d function to multiply vectors by the first matrix on the right of Eq. 4, the vectors being obtained by the multiplications between the second matrix and the vectors previously referred to.
  • all the adders 14b, 14d and 16c, 16d are supposed to have subtraction terminals. It is also possible, however, that all the adders comprise only addition terminals and that phase inverter circuits are used in place of the subtraction terminals. Further, if a circuit simultaneously providing a positive phase output and a negative phase output is employed, the
  • the construction becomes simple in comparsion with the circuit in FIG. 2. Since the four phase shifter circuits suffice, the matrix circuit can be manufactured inexpensively.
  • FIG. 4 Another embodiment according to the present invention will now be described with reference to FIG. 4.
  • the embodiment simplifies the construction of FIG. 3 by employing multi-input terminal adders.
  • the input unit 12, output terminals 13a 13d, adder 14d and phase shifter circuit 15d are the same as in FIG. 3.
  • Output terminals a 20d correspond to those 17a 17d in FIG. 3.
  • Phase shifter circuits A at 18a 18d are provided in order to hold phasic relations as in the case of FIG. 3.
  • Adders 19a 19d are the mult-input terminal adders.
  • the adder 190 is constructed by putting the adders 14a, 14c and 16a in FIG. 3 together, while the adder 19c by bringing the adders 14a, 14c and 16c.
  • the adders 19b 19d have subtraction terminals in the illustrated embodiment. As previously stated, however, it is also allowed to employ adders having only addition terminals and to utilize phase inverter circuits or the like instead.
  • phase shifter for use in the present invention will be briefly explained with reference to FIGS. 5 and 6.
  • R R designate resistance elements, C C capacitance elements, and T and T transistors.
  • a predetermined phase shift can be performed by approfrequency characteristics in thecase where the phase was intended to shift by .withphase shifters having the construction of FIG. 5 and differing in the amount of phase shift. It is shown that the phase was shifted by substantially 90 over Hz l0 k-Hz of the sound signal. 1
  • the quantities P P T T and 7 in the above equation may be substituted by T T S priately setting the values of the elements.
  • FIG. 6 shows 40 S and 7", respectively.
  • phase shifter circuits it is possible to commonly use the phase shifter circuits, with the result that five phase shifter circuits suffice.
  • Eq. 5 Even if simplifications are made using the relations of 7 1, 7' l etc., approximately 16 rs will still remain. This means the necessity for a number of phase shifter circuits, and becomes a disadvantage in bringing the matrices into the actual circuit.
  • a matrix circuit comprising first, second, third, and fourth input terminals; first arithmetic circuit means for'adding signals provided from said first and second input terminals; second arithmetic circuit means for subtracting said signal of said second input terminal from said signal of said first input terminal; third arithmetic circuit means for adding signals from said third and fourth input terminals; fourth arithmetic circuit means for subtracting said signal of said fourth input terminal from said signal of said third input terminal; first, second, and third phase shifters having a first phase shift which are respectively connected to the outputs of said first, second, and third arithmetic circuit means; a fourth phase shifter having a second phase shift connected to the output of said fourth arithmetic circuit means, fifth arithmetic circuit means for adding the outputs of said first and third phase shifters; sixth arithmetic circuit means for subtracting the output of said fourth phase shifter from the output of said second phase shifter; seventh arithmetic circuit means for subtracting said output of said third phase shifter
  • a matrix circuit comprising first, second, third, and fourth input terminals; first, second, third, and fourth phase shifters having a first phase shift which are respectively connected to said first, second, third, and fourth input terminals; first arithmetic circuit means for subtracting a signal of said fourth input terminal from a signal of said third input terminal; a fifth phase shifter having a second phase shift connected to the output of said first arithmetic circuit means; second arithmetic circuit means for producing a sum among outputs of said first, second, third, and fourth phase shifters; third arithmetic circuit means for subtracting said output of said second phase shifter from a sum between said outputof said first phase shifter and an output of said fifth phase shifter; fourth arithmetic circuit means for subtracting said outputs of said third and fourth phase shifters from a sum between said outputs of said first and second phase shifters; and fifth arithmetic circuit means for subtracting said output of said second phase shifter and said output of said fifth phase
  • Multi-channel sound system having first matriicircuit for encoding four directional input signals obtained from four signal sources arranged in such man ner that their azimuths on a plane are spaced by approximately 90, a plurality of transmission channel: for transmitting or recording the output signals of the first matrix circuit and a second matrix circuit for decoding the transmitted signal and reproducing fout directional output sound signals correlated with the input signals, wherein said matrix circuits include first second, third, and fourth input terminals; first arithme tic circuit means for adding the outputs of said first ant second input terminals; second arithmetic circui means for subtracting said signal of said second inpu terminal from said signal of said first input terminal third arithmetic circuit means for adding signals fron said third and fourth input terminals; fourth arithmetit circuit means for subtracting said signal of said fourtl input terminal from said signal of said third input termi nal; first, second, and third phase shifters having a firs phase shift which are respectively connected to th outputs of said first
  • Multi-channel sound system wherein the transmission channel consists of two transmission channels, one of which connects the first output terminal of the first matrix circuit to the first input terminal of the second matrix circuit and another one of which connects the third output terminal of said first matrix circuit to the third input terminal of said second matrix circuit.
  • Multi-channel sound system wherein the transmission channels are made up of four transmission channels which transmit the outputs of the first, second, third, and fourth output terminals of the first matrix circuit to first, second, third, and fourth input terminals of the second matrix circuit, respectively.
  • Multi-channel sound system having a first matrix circuit for encoding a four directional input signal obtained from four signal sources arranged in such manner that their azimuths on a plane are spaced by approximately 90, a plurality of transmission channels for transmitting the output signals of the signals of the first matrix circuit and a second matrix circuit for decoding the transmitted signal and reproducing directional output sound signals correlated with the input signals, wherein said matrix circuit includes first, sec- 0nd, third, and fourth input terminals; first, second, third, and fourth phase shifters having a first phase shift which are respectively connected to said first, second, third, and fourth input terminals; first arithmetic circuit means for subtracting a signal of said fourth input terminal from a signal of said third input terminal; a fifth phase shifter having a phase shift connected to the output of said first arithmetic circuit means; second arithmetic circuit means for producing a sum among outputs of said first, second, third, and fourth phase shifters; third arithmetic circuit means for subtracting said output of said
  • Multi-channel sound system wherein the transmission channel consists of two transmission channels, one of which connects the first output terminal of the first matrix circuit to the first input terminal of the second matrix circuit, and the other one of which channels connects the third output terminal of said first matrix circuit to the third input terminal of said second matrix circuit.
  • Multi-channel sound system wherein the transmission channels are made up of four transmission channels which transmit the outputs of the first, second, third, and fourth output terminals of the first matrix circuit to the first, second, third, and fourth input terminals of said second matrix circuit, respectively.

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Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4159397A (en) * 1977-05-08 1979-06-26 Victor Company Of Japan, Limited Acoustic translation of quadraphonic signals for two- and four-speaker sound reproduction
US4567607A (en) * 1983-05-03 1986-01-28 Stereo Concepts, Inc. Stereo image recovery
US4748669A (en) * 1986-03-27 1988-05-31 Hughes Aircraft Company Stereo enhancement system
US5850453A (en) * 1995-07-28 1998-12-15 Srs Labs, Inc. Acoustic correction apparatus
US5912976A (en) * 1996-11-07 1999-06-15 Srs Labs, Inc. Multi-channel audio enhancement system for use in recording and playback and methods for providing same
US5970152A (en) * 1996-04-30 1999-10-19 Srs Labs, Inc. Audio enhancement system for use in a surround sound environment
US6281749B1 (en) 1997-06-17 2001-08-28 Srs Labs, Inc. Sound enhancement system
US7031474B1 (en) 1999-10-04 2006-04-18 Srs Labs, Inc. Acoustic correction apparatus
US7636443B2 (en) 1995-04-27 2009-12-22 Srs Labs, Inc. Audio enhancement system
US7987281B2 (en) 1999-12-10 2011-07-26 Srs Labs, Inc. System and method for enhanced streaming audio
US8050434B1 (en) 2006-12-21 2011-11-01 Srs Labs, Inc. Multi-channel audio enhancement system
US9088858B2 (en) 2011-01-04 2015-07-21 Dts Llc Immersive audio rendering system
US9258664B2 (en) 2013-05-23 2016-02-09 Comhear, Inc. Headphone audio enhancement system

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3632886A (en) * 1969-12-29 1972-01-04 Peter Scheiber Quadrasonic sound system
US3745252A (en) * 1971-02-03 1973-07-10 Columbia Broadcasting Syst Inc Matrixes and decoders for quadruphonic records
US3746792A (en) * 1968-01-11 1973-07-17 P Scheiber Multidirectional sound system

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1359509A (en) * 1970-06-15 1974-07-10 Scheiber P Decoder apparatus for use in a multidirectional sound system

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3746792A (en) * 1968-01-11 1973-07-17 P Scheiber Multidirectional sound system
US3632886A (en) * 1969-12-29 1972-01-04 Peter Scheiber Quadrasonic sound system
US3745252A (en) * 1971-02-03 1973-07-10 Columbia Broadcasting Syst Inc Matrixes and decoders for quadruphonic records

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
Analysing Phase - Amplitude Matrices, by Scheiber, AES Preprint, Oct. 1971. *
Discrete-Matrix Multichannel Stereo, by Cooper & Shiga, Journal AES, June 1972, presented 10/7/71. *
Multichannel Stereo Matrix Systems: An Overview by Eargle Journal AES, July/August 1971. *

Cited By (29)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4159397A (en) * 1977-05-08 1979-06-26 Victor Company Of Japan, Limited Acoustic translation of quadraphonic signals for two- and four-speaker sound reproduction
US4567607A (en) * 1983-05-03 1986-01-28 Stereo Concepts, Inc. Stereo image recovery
US4748669A (en) * 1986-03-27 1988-05-31 Hughes Aircraft Company Stereo enhancement system
US7636443B2 (en) 1995-04-27 2009-12-22 Srs Labs, Inc. Audio enhancement system
US7043031B2 (en) 1995-07-28 2006-05-09 Srs Labs, Inc. Acoustic correction apparatus
US5850453A (en) * 1995-07-28 1998-12-15 Srs Labs, Inc. Acoustic correction apparatus
US6718039B1 (en) 1995-07-28 2004-04-06 Srs Labs, Inc. Acoustic correction apparatus
US20060062395A1 (en) * 1995-07-28 2006-03-23 Klayman Arnold I Acoustic correction apparatus
US7555130B2 (en) 1995-07-28 2009-06-30 Srs Labs, Inc. Acoustic correction apparatus
US5970152A (en) * 1996-04-30 1999-10-19 Srs Labs, Inc. Audio enhancement system for use in a surround sound environment
US20090190766A1 (en) * 1996-11-07 2009-07-30 Srs Labs, Inc. Multi-channel audio enhancement system for use in recording playback and methods for providing same
US8472631B2 (en) 1996-11-07 2013-06-25 Dts Llc Multi-channel audio enhancement system for use in recording playback and methods for providing same
US7492907B2 (en) 1996-11-07 2009-02-17 Srs Labs, Inc. Multi-channel audio enhancement system for use in recording and playback and methods for providing same
US7200236B1 (en) 1996-11-07 2007-04-03 Srslabs, Inc. Multi-channel audio enhancement system for use in recording playback and methods for providing same
US5912976A (en) * 1996-11-07 1999-06-15 Srs Labs, Inc. Multi-channel audio enhancement system for use in recording and playback and methods for providing same
US6281749B1 (en) 1997-06-17 2001-08-28 Srs Labs, Inc. Sound enhancement system
US7907736B2 (en) 1999-10-04 2011-03-15 Srs Labs, Inc. Acoustic correction apparatus
US7031474B1 (en) 1999-10-04 2006-04-18 Srs Labs, Inc. Acoustic correction apparatus
US8751028B2 (en) 1999-12-10 2014-06-10 Dts Llc System and method for enhanced streaming audio
US7987281B2 (en) 1999-12-10 2011-07-26 Srs Labs, Inc. System and method for enhanced streaming audio
US8050434B1 (en) 2006-12-21 2011-11-01 Srs Labs, Inc. Multi-channel audio enhancement system
US8509464B1 (en) 2006-12-21 2013-08-13 Dts Llc Multi-channel audio enhancement system
US9232312B2 (en) 2006-12-21 2016-01-05 Dts Llc Multi-channel audio enhancement system
US9088858B2 (en) 2011-01-04 2015-07-21 Dts Llc Immersive audio rendering system
US9154897B2 (en) 2011-01-04 2015-10-06 Dts Llc Immersive audio rendering system
US10034113B2 (en) 2011-01-04 2018-07-24 Dts Llc Immersive audio rendering system
US9258664B2 (en) 2013-05-23 2016-02-09 Comhear, Inc. Headphone audio enhancement system
US9866963B2 (en) 2013-05-23 2018-01-09 Comhear, Inc. Headphone audio enhancement system
US10284955B2 (en) 2013-05-23 2019-05-07 Comhear, Inc. Headphone audio enhancement system

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USB335741I5 (forum.php) 1975-01-28
DE2309591B2 (de) 1976-11-11
JPS4889702A (forum.php) 1973-11-22
DE2309591C3 (de) 1977-06-16
DE2309591A1 (de) 1973-09-13

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