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WO1979000560A1 - Circuit pour une compression ou une expansion dynamique automatique - Google Patents

Circuit pour une compression ou une expansion dynamique automatique Download PDF

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Publication number
WO1979000560A1
WO1979000560A1 PCT/DE1979/000003 DE7900003W WO7900560A1 WO 1979000560 A1 WO1979000560 A1 WO 1979000560A1 DE 7900003 W DE7900003 W DE 7900003W WO 7900560 A1 WO7900560 A1 WO 7900560A1
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WO
WIPO (PCT)
Prior art keywords
amplifier
circuit
expansion
input
signal path
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.)
Ceased
Application number
PCT/DE1979/000003
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German (de)
English (en)
Inventor
E Schroeder
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.)
Licentia Patent Verwaltungs GmbH
Original Assignee
Licentia Patent Verwaltungs GmbH
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 Licentia Patent Verwaltungs GmbH filed Critical Licentia Patent Verwaltungs GmbH
Publication of WO1979000560A1 publication Critical patent/WO1979000560A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G7/00—Volume compression or expansion in amplifiers
    • H03G7/002—Volume compression or expansion in amplifiers in untuned or low-frequency amplifiers, e.g. audio amplifiers

Definitions

  • the known systems have the difficulty, among other things, of fulfilling the following requirements as far as possible: low economic outlay; corresponding characteristic curves for compression and expansion; good reproducibility of the required values for the devices e.g. a production series and the expandability of the system concept with regard to the choice of the degree of expansion and compression.
  • the compression expansion systems known hitherto either require a relatively large outlay with good quality, or they do not sufficiently meet the above-mentioned requirements with a small outlay — in particular in the case of consumer devices.
  • the subject of the main patent relates to a circuit for automatic dynamic compression or expansion in a useful signal path with means for changing the transmission dimension, in which a path is branched off from the output or input of the useful signal path, on which a control voltage is generated from the useful signal path in a control voltage generator is obtained, which means to change the excess? is measured in the useful signal path.
  • the above-mentioned object is achieved in the main patent application in that the control voltage is also supplied to means in the branch path for changing the transmission dimension, in the sense of a counter regulation of the transmission dimension in the branch path.
  • the characteristic curves achievable with the circuit described have a first, linear part 1 with a gradient corresponding to a linear dynamics
  • the subject of the main patent relates to a circuit for automatic dynamic compression or expansion in a useful signal path with means for changing the transmission dimension, in which a path is branched off from the output or input of the useful signal path, on which a control voltage is generated from the useful signal path in a control voltage generator is obtained, which is fed to the means for changing the transmission dimension in the useful signal path.
  • the above-mentioned object is achieved in the main patent application in that the control voltage is also supplied to means in the branch path for changing the transmission dimension, in the sense of a counter regulation of the transmission dimension in the branch path.
  • FIG. 1 shows a characteristic diagram for the mode of operation of the known and the circuit according to the invention
  • FIGS. 2 and 3 each show an exemplary embodiment of the known one
  • Circuit and Fig. 4 and 5 de an embodiment of the circuit according to the invention.
  • FIG. 2 shows a known circuit (DT-OS 2529 012) for compressing AC signals as a block diagram.
  • DT-OS 2529 012 for compressing AC signals as a block diagram.
  • Such a circuit can e.g. be used when recording on a tape recorder.
  • an amplifier 8 whose gain can be controlled is arranged in the useful signal path between terminals 7 and 10.
  • the amplifier 8 has a control input 9, via which its gain can be controlled by means of a DC control voltage in order to change the transmission dimension.
  • a branch path with a further amplifier 11 is provided, the input of which is connected to the output of the amplifier 8.
  • the output of the amplifier 11 feeds, via a combination circuit 14, a control voltage sucker 13 which serves to generate a DC voltage at its output which is dependent on the amplitude of the input AC voltage.
  • This DC voltage is supplied as a control voltage to the control inputs 9 and 12 of the amplifiers 8 and 11.
  • the gain 11 of the amplifier 11, like the amplifier 8, can be influenced via the control input 12 via the control input 9.
  • the circuit described narrows the dynamic range of the useful signal, because with increasing output voltage of the Ver amplifier 8 at the output of the control voltage generator 13, a DC control voltage appears, which regulates the gain of the amplifier 8 down. In addition, the gain of the amplifier 11 is then also reduced, so that counter-regulation takes place in the branch path, which almost linearizes the control characteristic of the compression circuit shown logarithmically.
  • the control voltage is therefore a control voltage in FIG. 2. This effect is explained with reference to FIG. 1, the combining circuit 14 being initially disregarded.
  • Curve 1, 2, 3 for the dependence of the output level Up on U 1 represents the characteristic curve of the compression circuit according to FIG. 2. Between -75 dB and 60 dB for U 1 there is a constant gain of 30 dB (inclination of the characteristic part 1 of 45 °), so that if the maximum amplification of amplifiers 8 and 11 in FIG. 2 is assumed to be the same, there is an amplification of 60 dB at the output of amplifier 11 compared to the input voltage at input terminal 7.
  • the dynamic range of -75 dB to 0 dB of the input signal U 1 is reduced to a range of -45 dB to 0 dB of the output signals U 2 .
  • the expansion also proceeds in accordance with the compression.
  • the circuit according to FIG. 2 is provided with a combination circuit 14 which has two inputs 15 and 16 and an output which connects to the input of the control voltage generator 13 connected is.
  • the combination circuit 14 is constructed in such a way that a signal appears at its output which is equal to the difference between the two input signals, the signal value at input 16 being subtracted from the signal value at input 15.
  • the input 16 of the Vere 'in Trentsscrien 14 is supplied to the output voltage U 2 of the leading from the input terminal 7 through the amplifier 8 to the output terminal 10 Nutzsignalweges.
  • the connection of the combination circuit 14 described has the effect that a characteristic curve according to the characteristic curve 6 in FIG. 1 results for the circuit shown.
  • the characteristic curve 6 has a certain value at point 5 at an input level of 0 dB for U ,,. Below and above point 5, the characteristic curve 6 nestles asymptotically on the characteristic curve parts 2 and 3.
  • the curves shown in FIG. 1 only show the principle of operation of the combination circuit 14; it can be seen, however, that the characteristic curve 6 runs continuously in the area of the nominal level around 0 dB with respect to its differential quotient. Since the intersection 5 of the characteristic curve 6 with the ordinate can be reproduced exactly and without adjustment even with circuits from different production series, the circuit described with the characteristic curve 6 fulfills the requirements at the beginning called demands.
  • FIG. 3 shows the use of the circuit according to the invention in the expansion of AC voltage signals.
  • a circuit is used, for example, to expand the signals compressed from U 1 to U 2 with the circuit shown in FIG. 2 such that the output signals U 3 again have the dynamic range of the input signals U 1 of the circuit according to FIG. 2.
  • the expansion circuit according to FIG. 3 contains a controllable amplifier 19 between the input terminal 18 and the output terminal 20.
  • the branch path the input of which in this case is connected to the input of the amplifier 19 in the useful signal path instead of the output, contains the one already shown in FIG. 2 controllable amplifier 11 described.
  • the control input 21 of the amplifier 19 and the control input 12 of the amplifier 11 are fed by the output of the control voltage generator 13. Because of the expansion required, amplifier 19 is constructed in such a way that the slope of its characteristic curve has the opposite sign to the slope of the control characteristic curve of amplifier 8 from FIG. 2, while amplifier 11 in FIG. 3 corresponds to amplifier 11 in FIG. 2 and how this is counteracted.
  • a combination circuit 14 is inserted between the output of the amplifier 11 and the input of the control voltage generator 13, which corresponds to the combination circuit 14 in FIG. 2 and is constructed in the same way.
  • the input 16 of the combination circuit 14 is connected to the input of the amplifier 19.
  • the invention makes it possible to simplify the known circuit described above in that the combining circuit can be omitted.
  • the basis of the considerations leading there is the fact that the transmission dimension of an arrangement comprising a first amplifier and a differential amplifier, one input of the differential amplifier being connected to the input of the first amplifier and the other input of the differential amplifier being connected to the output of the first amplifier, by the amount formed by the differential amplifier from the transmission dimension of the first amplifier.
  • This difference in the amount of transmission is only dependent on the wiring of the differential amplifier. It therefore remains constant if the transmission factor of the first amplifier is varied.
  • the differential amplifier in the circuit described above is connected in such a way that the difference it forms has the amount 1.
  • FIG. 4 Such an arrangement is shown in FIG. 4 for the case of compression and in FIG. 5 for the case of expansion.
  • the compression circuit includes between the input terminal 7 and the output terminal 10 in a controllable gain thereof, preferably as a non-inverting amplifier formed amplifier 8.
  • the amplifier 8 bes ⁇ itzt a control input 9, via the. its gain can be controlled by means of a control voltage in order to change the transmission dimension.
  • a branch path with a further amplifier 11 is provided, the input of which is connected to the output of the amplifier 8.
  • the amplifier 11 arranged in the branch path is connected as an inverting amplifier.
  • the output of the amplifier 11 feeds a control voltage generator 13, which serves to generate a DC voltage at its output which is dependent on the amplitude of the input AC voltage.
  • This DC voltage is supplied as a control voltage to the control inputs 9 and 12 of the amplifiers 8 and 11.
  • the gain 11 of the amplifier 11, like the amplifier 8, can be influenced via the control input 12 via the control input 9.
  • the impedances used to connect the two amplifiers are the same. It is thereby achieved that with each possible control voltage at the control inputs 9 and 12, the amplifier 8 has one Gain greater than the amplifier 11 by the amount 1.
  • the expansion circuit according to FIG. 5 contains an amplifier 19 connected as a non-inverting amplifier in the signal path.
  • the amplifier 19 has a control input 21 via which its gain can be controlled by means of a DC control voltage in order to change the transmission dimension.
  • a branch path with a further amplifier 11 is provided, the input of which is connected to the input of the amplifier V arranged in the useful signal path. If the amplifier 19 arranged in the useful signal path is assumed to be a non-inverting amplifier, the amplifier 11 arranged in the branch path is connected as an inverting amplifier.
  • the output of the amplifier 11 feeds a control voltage generator 13, which serves to generate a DC voltage at its output which is dependent on the amplitude of the input AC voltage.
  • This DC voltage is supplied as a control voltage to the control inputs 21 and 12 of the amplifiers 19 and 11.
  • the amplifier 11, like the amplifier 19, can be influenced via the control input 12 in its gain.
  • the amplifier 19 is built up because of the expansion required so that the slope of its characteristic curve has the opposite sign as the slope of the characteristic curve of the amplifier 8 of FIG. 4 while the amplifier 11 in FIG. 5 matches the amplifier 11 in FIG. 4 and how this is counteracted.
  • the circuit variants mentioned in the known circuit are also possible.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Tone Control, Compression And Expansion, Limiting Amplitude (AREA)

Abstract

Dans un circuit pour une compression ou une expansion dynamique automatique, on a prevu un amplificateur reglable sur le cheminement du signal et un deuxieme amplificateur reglable dans un cheminement annexe pour l'obtention d'une tension de pilotage. Le facteur d'amplification de l'amplificateur se trouvant sur le cheminement du signal est superieur d'un facteur constant, par exemple "1" a celui de l'amplificateur se trouvant sur le cheminement annexe dans tout le domaine de pilotage. De ce fait la ligne "compression-expansion" n'a pas de discontinuite au point OdB et se comporte de facon continue par rapport a son quotient differentiel.
PCT/DE1979/000003 1978-01-28 1979-01-13 Circuit pour une compression ou une expansion dynamique automatique Ceased WO1979000560A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19782803751 DE2803751C2 (de) 1978-01-28 1978-01-28 Schaltung zur automatischen Dynamik- Kompression oder -Expansion
DE2803751 1978-01-28

Publications (1)

Publication Number Publication Date
WO1979000560A1 true WO1979000560A1 (fr) 1979-08-23

Family

ID=6030630

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/DE1979/000003 Ceased WO1979000560A1 (fr) 1978-01-28 1979-01-13 Circuit pour une compression ou une expansion dynamique automatique

Country Status (2)

Country Link
DE (1) DE2803751C2 (fr)
WO (1) WO1979000560A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU612157B2 (en) * 1987-06-27 1991-07-04 Sony Corporation Amplitude compressing/expanding circuit

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DK156356C (da) * 1980-06-30 1989-12-27 Ray Milton Dolby Kredsloeb til reduktion af overbelastningseffekter i signalindspilnings-og transmissionssystemer
PT74105B (en) * 1981-01-29 1983-06-15 Rca Corp Signal expander

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2529012A1 (de) * 1975-06-28 1977-01-20 Licentia Gmbh Schaltung zur automatischen dynamik- kompression oder -expansion

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2529012A1 (de) * 1975-06-28 1977-01-20 Licentia Gmbh Schaltung zur automatischen dynamik- kompression oder -expansion

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
J.G. GRAEME et al.: "Operational Amplifiers" Design and Applications (Burr-Brown) 1971, McGraw-Hill, New York see "Part" 1, "Design" chap. 5: Phase Compensation, paragraph 5.1: Frequency Stability and Bode Diagram Analysis, pages 166-174 *
NACHRICHTEN ELEKTRONIK, year 31, number 6, June 1977, Heidelberg G. Dickopp: "Telcom- Ein neues Telefunken Kompander-System", pages 161-163 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU612157B2 (en) * 1987-06-27 1991-07-04 Sony Corporation Amplitude compressing/expanding circuit

Also Published As

Publication number Publication date
DE2803751C2 (de) 1982-06-09
DE2803751A1 (de) 1979-08-02

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