US3087994A - Arrangement for the stereophonic reproduction of signals - Google Patents

Arrangement for the stereophonic reproduction of signals Download PDF

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Publication number
US3087994A
US3087994A US16214A US1621460A US3087994A US 3087994 A US3087994 A US 3087994A US 16214 A US16214 A US 16214A US 1621460 A US1621460 A US 1621460A US 3087994 A US3087994 A US 3087994A
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Prior art keywords
signals
stereophonic
resistor
frequency
circuit
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US16214A
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English (en)
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Schutte Rudolf
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US Philips Corp
North American Philips Co Inc
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US Philips Corp
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    • 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
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
    • H03D1/00—Demodulation of amplitude-modulated oscillations
    • H03D1/22—Homodyne or synchrodyne circuits
    • H03D1/2209—Decoders for simultaneous demodulation and decoding of signals composed of a sum-signal and a suppressed carrier, amplitude modulated by a difference signal, e.g. stereocoders
    • H03D1/2218—Decoders for simultaneous demodulation and decoding of signals composed of a sum-signal and a suppressed carrier, amplitude modulated by a difference signal, e.g. stereocoders using diodes for the decoding
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R5/00—Stereophonic arrangements
    • H04R5/04—Circuit arrangements, e.g. for selective connection of amplifier inputs/outputs to loudspeakers, for loudspeaker detection, or for adaptation of settings to personal preferences or hearing impairments
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04S—STEREOPHONIC SYSTEMS 
    • H04S1/00—Two-channel systems

Definitions

  • the arrangement described can be used in particular in a receiver for stereophonic broadcast reception, the sum signal A-l-B and the difference signal AB, which modulates the sub-carrier frequency in amplitude, modulating the broadcast carrier frequency in amplitude or in frequency, and also in magnetic tape reproducing apparatus, gramophones and the like.
  • the stereophonic reproducing arrangement in accordance with the invention is characterized in that the signals appearing at the input circuit of this arrangement, which comprise the audio-frequency sum signal A +B and the difference signal A-B which modulates the sub-carrier frequency in amplitude, are supplied together to two amplitude detection devices of oposite conductivity with respect to the audio-frequency sum signal A+B, the output circuit of each amplitude detection device being connected to the input of one of the separate channels.
  • FIG. 1 is a circuit diagram of a stereophonic broadcast receiver provided with an arrangement in accordance with the invention.
  • FIG. 2 is a circuit diagram of a transistorized stereophonic receiver.
  • the stereophonic receiver shown in FIG. 1 is designed for the reception of stereophonic signals which are transmitted as frequency-modulated signals modulating the same carrier frequency and comprise the sum signal A+B of the coherent stereophonic signals A and B, which may lie in the band of from 30 c./s. to 15,000 c./s., and a subcarrier frequency of 35 kc./s. which is amplitude modulated by the difference signal A-B, the modulation signal produced, which lies in the band of from 30 c./ s. to 50,000
  • the stereophonic receiver is provided with an antenna 1 and an intermediate-frequency stage 2 comprising a mixer stage and an oscillator 3 connected thereto, while the intermediate-frequency oscillations which are obtained from this oscillator by mixing and lie in the band of 10,700 kc./s., are supplied, after amplification and, if required, limitation in the intermediate-frequency stage 2, to an output band-pass filter comprising two coupled circuits 4 and 5.
  • the band-pass filter 4 and 5 forms part of a frequency detector of a type known for the detection of normal frequency-modulation transmissions which contains two rectifiers 6 and 7 which are connected, with opposite conductivity with respect to each other, between the ends of the circuit 5 and an output impedance 8, while a centre tapping on the circuit 5 is connected to the end of a coupling coil 9 coupled to the circuit coil 4.
  • the output impedance 8 of the frequency detector comprises a resistor 10 shunted by the series combination of two capacitors 11, 12, of which the junction is earthed, and by a smoothing capacitor 13, the output voltage of the frequency detector being taken from a centre tapping on the output resistor 10.
  • an output voltage appears which is produced by the sum signal A+B in the band of from 30 c./s. to 15,000 c./s. and by the diiference signal AB, which modulates the sub-carrier frequency in amplitude and lies in the frequency band of from 20 kc./s. to 50 kc./s., and this output voltage is supplied, through a blocking capacitor 14, to a. device 16, which will be described hereinafter, in order to recover the coherent stereophonic signals A and B, which are supplied, after low-frequency amplification in separate low-frequency amplifiers 17 and 18, to reproducing devices :19 and 20.
  • the low-frequency amplifiers 17 and 18, which are designed similarly, are constituted by triodes provided with grid leak resistors 21, 22 and not-shunted cathode resistors 23, 24 and 2-5, 26 which provide negative feed-back of the triodes 17, 13'.
  • the amplified coherent stereophonic signals A and -B are taken from output resistors 27 and 28 which are included in the anode circuits of the triode 17 and 18 and are connected, as is shown diagrammatically in the figure, to the reproducing devices 19 and 20- through blocking capacitors 29 and 30.
  • this output voltage which comprises the sum signal A+B and the difference signal AB, which modulates the sub-carrier frequency in amplitude, is supplied to the device 16 which is provided with two amplitude detection devices 31 and 32 of opposite polarities, the input circuits of these devices being connected in parallel with one another to the output circuit of the frequency detector 6, 7.
  • amplitude detection d vices are each provided with a rectifier cell 31 and 32 respectively and with the output impedance connected thereto which comprises the parallel combination of a resistor 33 and 34 respectively and a capacitor 35 and 36 respectively, the output voltages of the amplitude detection devices 31 and 32 being supplied, through blocking capacitors 37, 38 respectively, to the control grids of triodes 17 and 18 respectively, which are connected as low-frequency amplifiers.
  • the amplitude detection devices 31 and 32 are designed similarly.
  • both amplitude detection devices 31 and 32 effect an amplitude detection of the difference signal AB modulating the sub-carrier frequency, while the audio-frequency sum signal A-l-B acts as a threshold voltage for the two rectifier cells 31 and 32 which are connected with asymmetric conductivity with respect to each other, so that the operating points of the two rectifier cells 31 and 32 are shifted in opposite directions in accordance with the sum signal A-l-B.
  • a series resistor 39 which is at least equal to from A to /3 of the discharge resistors 33 and 34 of the detection capacitors 35 and 36, respectively, for it is found that due to the obtained increase in the charge time constant of the detection capacitors 35 and 36 relative to the discharge time constant of these capacitors 35 and 36, in the detection of the sub-carrier frequency, which is comparatively low as compared with the frequency of the voltage modulating it, detection distortions are reduced.
  • this object may alternatively be achieved by connecting a series resistor in series with the output impedances 33, 35 and 34, 36 of each of the amplitude detection devices 31 and 32.
  • cross-talk voltages have a fixed phase relationship with respect to the stereophonic signals A and B, in particular, these cross-talk voltages are substantially in phase with or in phase opposition to the stereophonic signals A and B.
  • an effective cross-talk reduction is achieved in a simple manner by the use of a method of compensation which consists in that an attenuator providing a suitable degree of attenuation is connected to a point of each of the reception channels, which attenuator is fed with a signal voltage which is derived from the other channel and is in phase opposition to the cross-talk voltage concerned.
  • the voltages in the two channels can be represented by:
  • two cross-talk factors a can have a positive or a negative value.
  • cross-talk is compensated for by the connection, between the two output impedances 33, 35 and 34, 36 respectively of the amplitude detection devices 31 and 32 respectively, of a connecting resistor 40 which is shunted by a capacitor 15, the time constant of this resistor 40* being approximately equal to the time constant of the output impedances 33, 35 and 34, 36 respectively of the amplitude-detection devices 31 and 32 respectively forms a frequency-independent voltage divider, so that through the network 44 15 a fraction of the output voltage of the amplitude detector 32 is supplied to the output circuit 33, 35 of the amplitude detector 31 and simultaneously a same fraction of the output voltage of the amplitude detector 31 is supplied to the output circuit 34, 36 of the amplitude detector 32.
  • the compensation is effected similarly in that a'connecting resistor 41 is connected between the cathode resistors 23, 24 and 25, 26 of the amplifier valves 17 and 18.
  • the grid leak resistors 21 and 22 of the amplifier valves 17 and 18 respectively are connected to tappings on the cathode resistors 23, 24 and 25, 26 respectively, so that larger cathode resistors 23, 24 and 25, 26 respectively can be used, and this is of advantage for practical reasons.
  • the stereophonic receiver described has all the features required for excellent stereophonic reproduction, namely a high quality of reproduction, a fixed phase relationship and cross-talk reduced to less than 30 to 40 db, which is amply sufficient for an excellent stereophonic reproduction.
  • the design of the stereophonic receiver is simple and its structure completely symmetrical, so that its cost can be materially reduced, for example, the amplifier valves 17, 18 can be designed as one double valve; the additional cost of the stereophonic receiver substantially amounts to the cost of an additional loudspeaker.
  • this stereophonic receiver is suitable to be used for stereophonic gramophone record reproduction while it can also be adapted to normal frequency-modulation reception by interconnecting the output circuits 33, 35 and 34, 36 of the two amplitude detection devices 31 and 32 by means of a switch 42.
  • Resistors 33, 34 100 KS2.
  • Resistor 40 10G KS2.
  • Resistor 41 100 KS2 variable. Valves 17, 18 ECC83.
  • the use of the connecting resistor 40 connected between the output impedances 33, 3'5 and 34, 36 provides additional advantages, for through this connecting resistor 40' a fraction of the signal voltage set up at the output impedance 33, 35 is supplied to the output impedance 33, 36 and conversely, so that there is produced at each of these output impedances 33, 35 and 34, 36 a signal component ,8(A;IB) which is in phase with the audio-frequency sum signal A-l-B supplied to the amplitude detection devices 31 and 32, with the result that the shifting of the operating points of the diodes 31 and 32 by this sum signal A+B is reduced, and this is of importance for a further improvement of the quality of reproduction.
  • FIG. 2 shows a transistorized stereophonic receiver of the type described. Similar elements are designated by like reference numerals.
  • a valve amplifier in the stereophonic receiver shown in this figure use is made of a transistor amplitier provided with two transistors 44 and 45 in common emitter arrangement.
  • Collector resistors 46 and 47 are connected in the collector circuits of the transistors 44 and 45, respectively, the reproducing devices 19 and being connected to these collector resistors through blocking capacitors 48 and 49 respectively, while the collectors are connected through resistors 50 and 51 respec tively to the associated bases.
  • Emitter resistors 52 and 53 are connected in the emitter circuits of the transistors 44 and 45 respectively, and connected together through a variable resistor 54 in order to provide cross-talk compensation.
  • the coherent stereophonic signals A and B are reproduced by the reproducing devices 19 and 20.
  • -B) is supplied, together and in series with the difference signal (AB) modulating the subcarrier frequency, to the amplitude detection devices 31, 32 connected with opposite conductivity to one another, however, for this purpose the sum signal A+B may alternatively be supplied in phase opposition to the two amplitude detection devices, in which event the amplitude detection devices must be connected with equal conductivity.
  • a frequency detector may be used the output circuit of which is connected in pushpull with respect to earth, either of the pushpull output voltages being supplied to one of the equally conductive amplitude detection devices. It is a feature of all these embodiments that the two amplitude detection devices to which the audio-frequency sum signal A -i-B and the difference signal AB, which modulates the sub-carrier frequency in amplitude, are supplied together, are 'connected with opposite conductivity with respect to the audio-frequency sum signal A+B. Tests have shown that the embodiments according to FIGS. 1 and 2 are to be preferred, inter alia by reason of their high quality of reproduction and the simplicity of their design.
  • the simplicity of the stereophonic reproducing arrangement described renders it very suitable for use for magnetic tape reproduction, for the audio-frequency sum signal A-i-B and the difference signal AB modulating the sub-carrier frequency can be recorded in one track by means of a single recording head, so that no radical alterations need be made in the existing magnetic tape recording apparatus.
  • a circuit for the stereophonic reproduction of signals of the type having a sum signal of first and second coherent stereophonic signals, and a difference signal of said first and second signals, said difference signal being in the form of amplitude modulation of a subcarrier said circuit comprising first and second amplitude detector circuits comprising first and second unidirectional current devices respectively, means applying said sum and difference signals to said first and second amplitude detector circuits, said first and second unidirectional current devices being connected with opposite polarities with respect to said sum signal, and means connected to said first and second detector circuits to derive first and second stereophonic output signals respectively.
  • a circuit for the stereophonic reproduction of signals of the type having a sum signal of first and second coherent stereophonic signals, and a diiference signal of said first and second signals, said difference signal being in the form of amplitude modulation of a subcarrier said circuit comprising means for providing said signals, first and second amplitude detector circuits having first and second unidirectional current devices respectively for detecting said difference signal and first and second impedance means connected to provide a bias for said first and second unidirectional current devices respectively, means applying said sum and difference signals to said first and second amplitude detector circuits, said applying means being connected to provide opposite conductivity of said unidirectional current devices with respect to said sum signal whereby opposite biases are provided by said sum signal on said unidirectional current devices, and means connected to said first and second detector circuits to derive first and second stereophonic output signals respectively.
  • a circuit for the stereophonic reproduction of signals of the type having a sum signal of first and second coherent stereophonic signals, and a diiference signal of said first and second signals, said difference signal being in the form of amplitude modulation of a subcarrier said circuit comprising means for providing said signals, first and second series circuits of first and second unidirectional current devices and first and second impedance means respectively, means applying said sum and difference signals to each of said series circuits for opposite current flow with respect to said sum signal, and means connected to said first and second series circuits for providing first and second output signals respectively.
  • a circuit for the stereophonic reproduction of signals of the type having a sum signal of first and second coherent stereophonic signals, and a difference signal of said first and second signals, said difference signal being in the form of amplitude modulation of a subcarrier said circuit comprising means for providing said signals, first and second terminals, a first series circuit of a unidirectional current device and a first impedance connected in that order between said first and second terminals, a second series circuit of a second unidirectional current device and a second impedance connected in that order between said first and second terminals, said unidirectional current devices being connected for opposite conductivity with respect to said terminals, means applying said sum and difference signals between said terminals, and means deriving first and second stereophonic output signals at the junctions of said first impedance and first unidirectional current device, and the junction of said second impedance and second unidirectional current device, respectively.
  • circuit of claim 4 comprising first and second electron discharge devices having grids and cathodes, means applying said first and second stereophonic output signals to the grids of said first and second discharge devices respectively, unshunted first and second resistors connected to the cathodes of said first and second discharge devices respectively, and resistor means connected between said first and second resistors.
  • circuit of claim 4 comprising first and second transistors having base, emitter, and collector electrodes, said transistors being connected in common emitter arrangement With unshunted emitter resistors, means applying said first and second output signals to the bases of said first and second transistors respectively, resistor means connected between the unshunted emitter resistors of said transistors, and first and second output circuits connected to the collectors of said first and second transistors respectively.
  • circuit of claim 4 comprising a crosstalk reducing resistor connected between the junction of said first impedance and first unidirectional current device, and the junction of said second impedance and said second unidirectional current device.
  • a circuit for the stereophonic reproduction of signals of the type having a sum signal of first and second coherent stereophonic signals, and a difference signal of said first and second signals, said difference signal being in the form of amplitude modulation of a subcarrier said circuit comprising means for providing said signals, first and second terminals, means applying said sum and difference signals between said terminals, a series resistor having one end connected to said first ter minal, first and second unidirectional current devices having opposite electrodes connected to the other end of said series resistor, first and second output resistors connected between the other ends of said first and second unidirectional current devices and said second terminal respectivly, first and scond capacitors connected in parallel with said first and second resistors respectively, and first and second output terminals connected to the junctions of said first and second resistors and said first and second unidirectional current devices respectively,
  • said series resistor having a value from A to /3 of the value of said first and second resistors.
  • a circuit for the stereophonic reproduction of signals of the type having a sum signal of first and second coherent stereophonic signals, and a difference signal of said first and second signals, said difference signal being in the form of amplitude modulation of a sub-car-rier said circuit comprising means for providing said signals, first and second terminals, a series resistor having one end connected to said first terminal, a first series circuit of a first unidirectional current device and first resistor connected in that order between the other end of said series resistor and said second terminal, a second series circuit of a second unidirectional current device and a second resistor connected in that order between the other end of said series resistor and said second terminal, first and second capacitors connected in parallel with said first and second resistors respectively, means applying said sum and difference signals between said first and second terminals, said unidirectional current devices being connected for opposite conductivity with respect to said terminals, first and second amplifying devices having input electrodes, common electrodes, and output electrodes, means connecting the junction of said first unidirectional current device and first resistor
  • circuit of claim 10 comprising resistor means connected between said third and fourth resistors.
  • circuit of claim 10 comprising means for selectively interconnecting the junction of said first unidirectional current device and first resistor and the junction of said second unidirectional current device and second resistor for reception of non-stereophonic signals.
  • the circuit of claim 10 comprising a crosstalk reducing resistor connected between the junction of said first unidirectional current device and said first resistor and the junction of said second unidirectional current device and said second resistor.

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Stereo-Broadcasting Methods (AREA)
US16214A 1959-03-23 1960-03-21 Arrangement for the stereophonic reproduction of signals Expired - Lifetime US3087994A (en)

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NL237409 1959-03-23
NL248992 1960-03-02

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US16214A Expired - Lifetime US3087994A (en) 1959-03-23 1960-03-21 Arrangement for the stereophonic reproduction of signals

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CH (2) CH392628A (es)
DE (2) DE1100086B (es)
FR (2) FR1251873A (es)
GB (2) GB926357A (es)
NL (4) NL103480C (es)
OA (1) OA00826A (es)
SE (1) SE303310B (es)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3152224A (en) * 1962-08-01 1964-10-06 Zenith Radio Corp F. m. stereophonic multiplex receiver having a single volume control for adjusting the magnitude of the signals presented to the stereo detector and the output materixing means
US3187102A (en) * 1962-02-22 1965-06-01 Philips Corp Stereo multiplex receiver with automatic stereo or monaural detection and indicating means
US3219759A (en) * 1960-10-31 1965-11-23 Gen Electric System for deemphasizing and separating amplitude modulation components from a signal
US3242264A (en) * 1961-06-19 1966-03-22 Zenith Radio Corp Monophonic and stereophonic frequency-modulation receiver
US3248484A (en) * 1965-01-14 1966-04-26 Zenith Radio Corp Fm multiplex stereo receiver having selective bias to condition receiver for stereophonic reception only
US3329773A (en) * 1962-08-20 1967-07-04 Matsushita Electric Ind Co Ltd Method of selecting an fm stereophonic signal

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3258537A (en) * 1961-11-16 1966-06-28 Gen Dynamics Corp Frequency modulation sum and difference stereo having pre-detection compensating means
GB1051619A (es) * 1962-09-07
US3272922A (en) * 1963-12-31 1966-09-13 Gen Electric Receiver circuit for stereo separation
US3339025A (en) * 1965-06-01 1967-08-29 Gen Electric De-emphasis network arrangement for am-fm radios
US4198543A (en) * 1979-01-19 1980-04-15 General Motors Corporation Stereo composite processor for stereo radio receiver
SE467797B (sv) * 1991-01-16 1992-09-14 Excelsior Dev Inc Momentmutter eller momentskruv med koniskt gaengfoerband

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2698379A (en) * 1951-04-28 1954-12-28 Philips Nv Transmission system for stereophonic signals
US2851532A (en) * 1953-04-21 1958-09-09 Murray G Crosby Multiplex communication system

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2698379A (en) * 1951-04-28 1954-12-28 Philips Nv Transmission system for stereophonic signals
US2851532A (en) * 1953-04-21 1958-09-09 Murray G Crosby Multiplex communication system

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3219759A (en) * 1960-10-31 1965-11-23 Gen Electric System for deemphasizing and separating amplitude modulation components from a signal
US3242264A (en) * 1961-06-19 1966-03-22 Zenith Radio Corp Monophonic and stereophonic frequency-modulation receiver
US3187102A (en) * 1962-02-22 1965-06-01 Philips Corp Stereo multiplex receiver with automatic stereo or monaural detection and indicating means
US3152224A (en) * 1962-08-01 1964-10-06 Zenith Radio Corp F. m. stereophonic multiplex receiver having a single volume control for adjusting the magnitude of the signals presented to the stereo detector and the output materixing means
US3329773A (en) * 1962-08-20 1967-07-04 Matsushita Electric Ind Co Ltd Method of selecting an fm stereophonic signal
US3248484A (en) * 1965-01-14 1966-04-26 Zenith Radio Corp Fm multiplex stereo receiver having selective bias to condition receiver for stereophonic reception only

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Publication number Publication date
NL248992A (es)
SE303310B (es) 1968-08-26
NL107891C (es)
US3123673A (en) 1964-03-03
FR1251873A (fr) 1961-01-20
CH392628A (de) 1965-05-31
NL237409A (es)
CH425898A (de) 1966-12-15
GB926357A (en) 1963-05-15
NL103480C (es)
DE1100086B (de) 1961-02-23
OA00826A (fr) 1967-11-15
GB949225A (en) 1964-02-12
DE1122578B (de) 1962-01-25
FR79291E (fr) 1962-11-09

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