US3845245A - Encoding system for forming two-channel signals from a plurality of sound signals - Google Patents

Encoding system for forming two-channel signals from a plurality of sound signals Download PDF

Info

Publication number
US3845245A
US3845245A US00414512A US41451273A US3845245A US 3845245 A US3845245 A US 3845245A US 00414512 A US00414512 A US 00414512A US 41451273 A US41451273 A US 41451273A US 3845245 A US3845245 A US 3845245A
Authority
US
United States
Prior art keywords
sound
sound signal
channel
coupling
signals
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00414512A
Other languages
English (en)
Inventor
S Takahashi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sansui Electric Co Ltd
Original Assignee
Sansui Electric Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sansui Electric Co Ltd filed Critical Sansui Electric Co Ltd
Application granted granted Critical
Publication of US3845245A publication Critical patent/US3845245A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04H—BROADCAST COMMUNICATION
    • H04H20/00—Arrangements for broadcast or for distribution combined with broadcast
    • H04H20/86—Arrangements characterised by the broadcast information itself
    • H04H20/88—Stereophonic broadcast systems
    • H04H20/89—Stereophonic broadcast systems using three or more audio channels, e.g. triphonic or quadraphonic
    • 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

Definitions

  • ABSTRACT In an encoding system in which front-left and right audio input signals are coupled to left and right channels with a reference phase-shift angle, and back-left and right audio input signals are coupled to the left channel with the reference phase-shift angle plus 90 and to the right channel with the reference phase-shift angle minus 90, a left-center audio input signal is coupled in a large proportion to the left channel with the reference phase-shift angle and in a small proportion to the right channel with the reference phase-shift angle minus 90 and a right-center signal is coupled in a large proportion to the right channel with the reference phase-shift angle and in a small proportion to the left channel with the reference phase-shift angle plus 90.
  • R RF+ALFjRBjALB (n where A denotes a matrix coefficient whose typical value is 0.414.
  • the customary practice is to couple a left-center signal LC and right-center signal RC to the left and right channels L and R respectively with the reference phase shift amount.
  • the decoder is provided with a control unit for detecting the level relationship of front and back signals and generating a first and a second control output.
  • Equation (1) above shows that where the back signals LB and RB have a negligible amplitude as compared with that of the front signals LF and RF the twochannel signals are substantially in phase, and that conversely where the front signals LF and RF have a negligible amplitude as compared with that of the back signals LB and RR, the two-channel signals are substantially 180 out of phase. In case of LF RF LB RB, the two-channel signals are 90 out of phase.
  • the first control output takes a positive maximum value with respect to the referential voltage level whereas the second control output assumes a negative maximum value, or vice versa where the two-channel signals L and R are 180 out of phase.
  • the first and second control outputs have a voltage level equal to the referential voltage level.
  • one type of prior art decoder enhances separation between front-left and right reproduced signals, but reduces separation between back-left and right reproduced signals and also increases the voltage level of the front signals and decreases that of the back signals, thereby promoting separation between the front and back reproduced signals.
  • the prior art decoder carries out an opposite operation to that mentioned above.
  • the decoder is operated in the same manner as the other conventional decoders without changing the matrix coefficients.
  • a decoder carrying out the above-mentioned operation is supplied with, for example, a right signal R and a left signal L including a left-center signal LC
  • the control unit does not act on the left-center signal LC. Therefore, this signal LC is reproduced by the leftfront loudspeaker and left-back loudspeaker with an equal level.
  • two-channel signals are supplied to the decoder generally after being reproduced through a pickup cartridge from a phonographic record, it is difficult to prevent the left-center signal from necessarily appearing in the right signal R as a crosstalk component. In this case, it is also difficult to determine whether the crosstalk component has the same or opposite phase with respect to the original signal or the left-center signal. In either case, existence of the left-center signal causes the decoder to take the erroneous action of controlling the front and back signals.
  • Another object of the invention is to provide an ,encoding system capable of producing two-channel signals in the form adapted for a decoder to reproduce separation enhanced output signals.
  • an encoding system in which at least first to fourth sound signals desired to be coupled mainly to first to fourth loudspeakers surrounding a listener are utilized in forming first and second channel signals, and first and second sound signals are coupled to the first channel in large and small proportions respectively with a reference phase shift amount, second and first sound signals are coupled to the second channel in large and small proportions respectively with the reference phase shift amount, third and fourth sound signals are coupled to the first channel in large and small proportions respectively with a phase shift amount of the reference phase shift amount plus 90, and the fourth and third sound signals are coupled to the second channel in large and small proportions with a phase shift amount of the reference phase shift amount minus 90, the improvement comprising means for coupling a fifth sound signal desired to have its sound image localized between the first and third loudspeakers to the first channel in a large proportion with the reference phase shift amount; means for coupling the fifth sound signal to the second channel in a small proportion with a phase shift amount having substantially 90 phase difference with respect to the reference phase
  • FIG. 1 is a circuit diagram of an encoding system according to one embodiment of this invention.
  • FIG. 2 is vector diagrams given for better understanding of the invention.
  • reference numerals 11 to 14 denote input terminals supplied with LF, LB, RB and RF audio input signals respectively. These input terminals are connected to a resistance matrix circuit 15 containing resistors 16 to 21. A sum output of an LF signal having a large proportion and an RF signal having a small proportion is drawn out from the junction of the resistor 16 and blend resistor 20. This output is coupled to a first phase shifter 22. Further, a sum output of an RF signal having a large proportion and an LF signal having a small proportion is delivered from the junction of the resistor 19 and blend resistor 20. This output is coupled to a second phase shifter 23.
  • a sum output of an LB signal having a large proportion and an RB signal having a small proportion is obtained from the junction of the resistor 17 and blend resistor 21. This output is coupled to a third phase shifter 24. Further, a sum output of an RB signal having a large proportion and an LB signal having a small proportion is taken out of the junction of the resistor 18 and blend resistor 21. This output is coupled to a fourth phase shifter 25.
  • Output signals from the first and third phase shifters 22 and 24 are coupled to an output terminal 26 through an adder 27 to produce a left-channel signal L.
  • Output signals from the second and fourth phase shifters 23 and 25 are coupled to an output terminal 28 through an adder 29 to produce a right-channel signal R.
  • the first and second phase shifters 22 and 23 have substantially the same phase-shifting characteristic over entire audible frequency range, so as to shift the phase of input signal thereto by an reference angle 4).
  • the third phase shifter 24 has a phase-shifting characteristic so as to shift the phase of input signal thereto by the reference angle 11) plus 90 and the fourth phase shifter has a phase shifting charactcristic so as to the phase of input signals by the reference angle 4) minus 90. Accordingly, left and right channel signals L and R obtained at the output terminals 26 and 28 can obviously be indicated by the afore mentioned equation (1).
  • Reference numerals 30 and 31 show input terminals supplied with a left-center signal LC and a right-center signal RC respectively.
  • the LC signal is coupled to the first phase shifter 22 in a large proportion and to the fourth phase shifter 25 through a resistor 32 in a small portion.
  • the RC signal is coupled to the second phase shifter 23 in a large proportion and to the third phase shifter 24 through a resistor 33 in a small portion.
  • the resistors constituting the resistor matrix circuit 15 are chosen to have such resistance values as to cause the ratio of the small proportion to the large proportion of the LF, LB, RB and RF to indicate a value of 0.414.
  • the small and large proportions of the LC and RC signals may be so chosen as to have a ratio of, for example, 0.01 to 0.1 (or 40 db to 20db).
  • the rightchannel signal R contains a right-center signal RCO
  • the reproduced left-channel signal L will be contaminated by a crosstalk component ARCl (about 30db) having the same phase as that of the RC0 signal or another crosstalk component ARC2 having an opposite phase from that of the RC0 signal.
  • the left signal L is contaminated by a third crosstalk component ARC3 (about 20db) which was carried into the left signal L on the encoder side in quadrature with the RC0 signal.
  • the reproduced left-channel signal L contains a resultant crosstalk component ARC4 formed of crosstalk components ARC3 and ARCl or a resultant crosstalk component ARCS formed of crosstalk components ARC3 and ARCZ. Since the crosstalk component ARCl or ARC2 has a smaller proportion than the crosstalk component ARC3, the resultant crosstalk ARC4 or ARCS is approximately in quadrature with the aforesaid RCO component. Accordingly, the reproduced two-channels L and R are in quadrature with each other with respect to the left-center signal LC or right-center signal RC. Where, therefor, such two-channel signals are supplied to the previously described separation enhancing decoder, then the existence of the LC or RC signal can substantially prevent the front and back signals from being controlled by mistake.
  • the left-center signal LC and the right-center signal RC of a small proportion are coupled to the right and left channels with phase-shifts of 90 and d respectively
  • the left-center signal LC of a small proportion may be coupled to the right channel with a phase-shift of +90 and the rightcenter signal RC to the left channel with a phase-shift of 90.
  • An encoding system in which at least first to fourth sound signals desired to be coupled mainly to first to fourth loudspeakers surrounding a listener are utilized in forming first and second channel signals, and first and second sound signals are coupled to the first channel in large and small proportions respectively with a reference phase shift amount, second and first sound signals are coupled to the second channel in large and small proportions respectively with the reference phase shift amount, third and fourth sound signals are coupled to the first channelin large and small proportions respectively with a phase shift amount of the reference phase shift amount plus 90, and the fourth andthird sound signals are coupled to the second channel in large and small proportions with a phase shift amount of the reference phase shift amount minus 90, the improvement comprising means for coupling a fifth sound signal desired to have its sound image localized between said first and third loudspeakers to the first channel in a large proportion with the reference phase shift amount; means for coupling said fifth sound signal to the second channel in a small proportion with a phase shift amount having substantially 90 phase difference with respect to the reference phase shift amount; means for coupling a sixth
  • An encoding system for encoding at least first to fourth sound signals desired to be coupled mainly to first to fourth loudspeakers surrounding a listener into first and second channel signals, comprising first means for mixing the first sound signal in a large proportion and the second sound signal in a small proportion; second means for mixing the second sound signal in a large proportion and the first sound signal in a small proportion; third means for mixing the third sound signal in a large proportion and a fourth sound signal in a small proportion; fourth means for mixing the fourth sound signal in a large proportion and the third sound signal in a small proportion; a first phase shifter coupled to the output of said first means; a second phase shifter coupled to the output of said second means and having substantially the same phase shifting characteristic as said first phase shifter over the entire audible frequency range; a third phase shifter coupled to the output of said third means and having a phase shifting characteristic of plus 90 difference with respect to those of said first and second phase shifters; a fourth phase shifter coupled to the output of said fourth means and having a phase shifting characteristic of
  • An encoding system for coupling to the firstand second channels first to fourth sound signals desired to be coupled mainly to first to fourth loudspeakers surrounding a listener comprising: means for coupling the first and second sound signal to the first channel in large and small proportions respectively with a reference phase shift amount; means for coupling the second and first sound signals to the second channel in large and small proportions respectively with the reference phase shift amount; means for coupling the third and fourth sound signals to the first channel in large and small proportions respectively with the reference phase shift amount plus 90; means for coupling the fourth and third sound signals to the second channel in large and small proportions with the reference phase shift amount minus 90; means for coupling a fifth sound signal desired to have its sound image localized between the first and third loudspeakers to the first channel in a large proportion with the reference phase shift amount; means for coupling the fifth sound signal to the second channel in a small proportion with a phase shift amount having substantially phase difference with respect to the reference phase shift amount; means for coupling a sixth sound signal desired to have its sound image localized between
  • An encoding system for encoding first to fourth sound signals desired to be coupled mainly to first to fourth loudspeakers surrounding a listener into first and second channel signals comprising: first to fourth input terminals adapted to receive the first to fourth sound signals respectively; a fifth input terminal adapted to receive a fifth sound signal desired to have its sound image localized between the first and third loudspeakers; a sixth input terminal adapted to receive a sixth sound signal desired to have its sound image localized between the second and fourth loudspeakers; first and second output terminals; matrix means connected to said first to fourth input terminals so as to form first, second, third and fourth output signals, said first output signal being a sum of the first sound signal having a large amplitude and the second sound signal having a small amplitude, said second output signal being a sum of the first sound signal having a small amplitude and the second sound signal having a large amplitude, said third output signal being a sum of the third sound signal having a large amplitude and the fourth sound signal having a small amplitude

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Signal Processing (AREA)
  • Mathematical Physics (AREA)
  • Mathematical Analysis (AREA)
  • Mathematical Optimization (AREA)
  • General Physics & Mathematics (AREA)
  • Pure & Applied Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Algebra (AREA)
  • Multimedia (AREA)
  • Stereophonic System (AREA)
  • Stereo-Broadcasting Methods (AREA)
  • Reduction Or Emphasis Of Bandwidth Of Signals (AREA)
US00414512A 1972-12-29 1973-11-09 Encoding system for forming two-channel signals from a plurality of sound signals Expired - Lifetime US3845245A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP732774A JPS5246681B2 (enrdf_load_stackoverflow) 1972-12-29 1972-12-29

Publications (1)

Publication Number Publication Date
US3845245A true US3845245A (en) 1974-10-29

Family

ID=11538671

Family Applications (1)

Application Number Title Priority Date Filing Date
US00414512A Expired - Lifetime US3845245A (en) 1972-12-29 1973-11-09 Encoding system for forming two-channel signals from a plurality of sound signals

Country Status (4)

Country Link
US (1) US3845245A (enrdf_load_stackoverflow)
JP (1) JPS5246681B2 (enrdf_load_stackoverflow)
DE (1) DE2355888C3 (enrdf_load_stackoverflow)
GB (1) GB1422832A (enrdf_load_stackoverflow)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4577305A (en) * 1983-03-14 1986-03-18 Dolby Laboratories Licensing Corporation Stereophonic motion picture photographic sound-tracks compatible with different sound projection formats and record and playback apparatus therefore
US4812921A (en) * 1985-12-18 1989-03-14 Sony Corporation Sound field expansion system for a video tape recorder

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS56143131U (enrdf_load_stackoverflow) * 1980-03-28 1981-10-28

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3745252A (en) * 1971-02-03 1973-07-10 Columbia Broadcasting Syst Inc Matrixes and decoders for quadruphonic records
US3777076A (en) * 1971-07-02 1973-12-04 Sansui Electric Co Multi-directional sound system
US3787622A (en) * 1971-02-05 1974-01-22 Sansui Electric Co Quadrasonic sound system for two channel transmission

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3745252A (en) * 1971-02-03 1973-07-10 Columbia Broadcasting Syst Inc Matrixes and decoders for quadruphonic records
US3787622A (en) * 1971-02-05 1974-01-22 Sansui Electric Co Quadrasonic sound system for two channel transmission
US3777076A (en) * 1971-07-02 1973-12-04 Sansui Electric Co Multi-directional sound system

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Proposed Universal Encoding Standards for Compatible Four-Channel Matrixing, by Itoh, Journal AES April 1972. *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4577305A (en) * 1983-03-14 1986-03-18 Dolby Laboratories Licensing Corporation Stereophonic motion picture photographic sound-tracks compatible with different sound projection formats and record and playback apparatus therefore
EP0119101A3 (en) * 1983-03-14 1986-08-27 Dolby Laboratories Licensing Corporation Improvements in stereophonic motion picture photographic sound-tracks and apparatus for recording and playing back photographic sound tracks
US4812921A (en) * 1985-12-18 1989-03-14 Sony Corporation Sound field expansion system for a video tape recorder

Also Published As

Publication number Publication date
DE2355888C3 (de) 1975-10-23
DE2355888A1 (de) 1974-07-11
JPS4991401A (enrdf_load_stackoverflow) 1974-08-31
JPS5246681B2 (enrdf_load_stackoverflow) 1977-11-26
DE2355888B2 (de) 1975-03-20
GB1422832A (en) 1976-01-28

Similar Documents

Publication Publication Date Title
US3725586A (en) Multisound reproducing apparatus for deriving four sound signals from two sound sources
US3825684A (en) Variable matrix decoder for use in 4-2-4 matrix playback system
US3783192A (en) Decoder for use in matrix four-channel system
US3885101A (en) Signal converting systems for use in stereo reproducing systems
US3757047A (en) Four channel sound reproduction system
US6760448B1 (en) Compatible matrix-encoded surround-sound channels in a discrete digital sound format
KR100364333B1 (ko) 신호처리회로와,신호처리회로를포함하는입체음향오디오재생시스템
US3883692A (en) Decoder apparatus with logic circuit for use with a four channel stereo
US3745252A (en) Matrixes and decoders for quadruphonic records
US3821471A (en) Apparatus for reproducing quadraphonic sound
US4516257A (en) Triphonic sound system
US3845245A (en) Encoding system for forming two-channel signals from a plurality of sound signals
US3835255A (en) Matrix decoders for quadraphonic sound system
US3892918A (en) Sound signal converting apparatus for use in a four channel stereophonic reproduction system
US3777076A (en) Multi-directional sound system
US3787622A (en) Quadrasonic sound system for two channel transmission
US3818136A (en) Four-channel front-to-back balance control
EP0060097B1 (en) Split phase stereophonic sound synthesizer
US3792199A (en) Reproducer device for fm stereo multiplex signals
US3887770A (en) Decoder apparatus adapted for different 4-channel matrix systems
US3979564A (en) 4-Channel stereo recording and reproducing method
US3813494A (en) Quadraphonic reproducing system
US4115666A (en) Discrete 4-channel stereo recording and/or reproducing system compatible with matrix systems
US3890466A (en) Encoders for quadraphonic sound system
USRE29171E (en) Multi-directional sound system