US2112279A - Automatic gain control circuits - Google Patents

Automatic gain control circuits Download PDF

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Publication number
US2112279A
US2112279A US100069A US10006936A US2112279A US 2112279 A US2112279 A US 2112279A US 100069 A US100069 A US 100069A US 10006936 A US10006936 A US 10006936A US 2112279 A US2112279 A US 2112279A
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United States
Prior art keywords
control
frequency
radio
gain
amplifier
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Expired - Lifetime
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US100069A
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English (en)
Inventor
Hagenhaus Kurt
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Telefunken AG
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Telefunken AG
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Publication of US2112279A publication Critical patent/US2112279A/en
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G7/00—Volume compression or expansion in amplifiers

Definitions

  • Fig. 1 shows a circuit arrangement employing one form of the invention
  • Figs. 2 to 6 inclusive show respectively different modifications of the invention, and wherein in each modification the gain expansion bias is applied to a radio frequency amplifier.
  • the control potential and hence also the low-frequency potential which at a definite degree of modulation is obtained in the same manner as the control potential from the high-frequency, does not remain constant, since otherwise no controlling action occurs.
  • the low-frequency amplitude depends only upon the degree of modulation of the respective transmitter.
  • Figs. 1 and 2 Examples of embodiments of this aspect of the invention are schematically shown in Figs. 1 and 2.
  • Fig. 1 there is placed in the output of the high-frequency stage HF1, the detector Gs which furnishes the gain control potential (after filtering out the low-frequency) for the preceding high-frequency stage (HF1) and for the subsequent high-frequency stage (HFz).
  • the receiving detector GE always utilizes the same high-frequency amplitudes so that also the low-frequency amplitudes are always the same at the same degree of modulation.
  • the intensity range control oper-i ates by means of the detector GD which detects the low-frequency energy, entirely independent of the input potentials of the receiver.
  • the intensity range control operates on the high-frequency stages. It would also be possible to combine the arrangements of Figs. 1 and 2. Also other modes of structures are possible, as the high-freequency stage I-IFz could for instance be omitted, and a part of the gain control and also the intensity range control could be carried out in the low-frequency part. In this case, the gain control potential may also be derived from the receiving detector. On the other hand, the detector for the intensity range control may be connected to the output of the detector for the gain control.
  • Figs. 3 and 4 Two examples of this phase of the invention are schematically shown in Figs. 3 and 4.
  • the control detector Gs for the gain control is connected to the output of the high-frequency stage HF1. Following the filtering out of the low frequency potentials, the control potential acts upon the high-frequency stage I-IF1. But these low-frequency potentials are applied to the detector GD which serves for the control of the intensity range. This control is carried out at the high-frequency stage HFz, and provides expansion of gain thereof.
  • the lowfrequency produced in the receiving detector GE is applied to the detector Go for the control of the intensity range.
  • the output of this detector is connected to the high-frequency stage HFz.
  • the rectifier Gs provides the usual AVC action.
  • a gain control, or control of the intensity range is carried out at one or several stages of a high-frequency receiver.
  • This phase of the invention has advantages in receivers in which a limited power reserve is available.
  • the gain control and also the intensity range control each require a reserve of power in order that they be fully efiective. Hence, both together can only be used in larger receivers.
  • the construction now to be described affords the possibility of still utilizing the advantages of both controls.
  • the intensity range control will only be connected at local reception, or to receive signals from powerful transmitters not subject to fading phenomena, while, on the other hand, for distance reception more importance is to be attached to compensating the fading phenomena, since in this case the intensity range control would act in a false manner, in view of the changing input potentials.
  • Figs. 5 and 6 Examples embodying this aspect of the invention are schematically shown in Figs. 5 and 6.
  • a detector Gs is connected for the gain control to correct for fading, and which controls the high-frequency stage.
  • the control could also be carried out at the receiving detector GE.
  • the low, or audio, frequency energy appearing in the output of the receiving detector will be detected in the detector GD.
  • This control potential will only then be applied to the highfrequency stage HF, when the switch S is in the downward position.
  • the detected audio component is used for expansion of the R. F. amplifier gain.
  • Figure 6 differs from Figure 5 in that the audiofrequency potential for the intensity range control is derived from the detector Gs, and detected in the detector GD.
  • a gain control potential or a potential of the intensity range control, is applied to the highfrequency stage HFz.
  • a gain control is always carried out at the high-frequency stage HF1, so that at the right hand position of switch S, a complete gain control will be effected.
  • a radio receiver of the type including at least two radio frequency amplifiers in cascade, an audio demodulator, an audio amplifier and a reproducer, an automatic volume control circuit responsive to the signal output of the first radio amplifier for controlling the gain of the latter, and an automatic gain expansion circuit, responsive to the audio component of detected signals, for controlling the gain of the second radio amplifier in a sense opposite to the gain control of the first radio amplifier.
  • a radio receiver of the type including at least two radio frequency amplifiers in cascade, an audio demodulator, an audio amplifier and a reproducer, an automatic volume control circuit responsive to the signal output of the first radio amplifier for controlling the gain of the latter, an automatic gain expansion circuit, responsive to the audio component of detected signals, for controlling the gain of the second radio amplifier in a sense opposite to the gain control of the first radio amplifier, said volume control circuit including a signal rectifier, and said expansion circuit including a rectifier connected to the output of said signal rectifier.
  • a radio receiver of the type including at least two radio frequency amplifiers in cascade, an audio demodulator, an audio amplifier and a reproducer, an automatic volume control circuit responsive to the signal output of the first radio amplifier for controlling the gain of the latter, and an automatic gain expansion circuit, responsive to the audio component of detected signals, for controlling the gain of the second radio amplifier in a sense opposite to the gain control of the first radio amplifier, said volume control circuit including a rectifier connected to the first radio amplifier output circuit, and said expansion circuit including a device for rectifying the audio component of the rectified output of said rectifier.
  • a radio receiver of the type including at least two radio frequency amplifiers in cascade, an audio demodulator, an audio amplifier and a reproducer, an automatic volume control circuit responsive to the signal output of the first radio amplifier for controlling the gain of the latter, an automatic gain expansion circuit, responsive to the audio component of detected signals, for controlling the gain of the second radio amplifier in a sense opposite to the gain control of the first radio amplifier, said expansion circuit including a rectifier for rectifying the said audio component, and means for applying the rectified audio component to the second radio amplifier.
  • a radio receiver of the type including a radio frequency amplifier network, a demodulator, an audio frequency amplifier network and a reproducer, means responsive to variations in modulated signal carrier amplitude for automatically controlling the carrier transmission efficiency through the radio amplifier network in a sense to maintain the carrier amplitude at the demodulator input substantially uniform regardless of fading at the radio amplifier network input, and additional means, responsive to an increase in the audio component amplitude of the modulated signal carrier, for increasing the said transmission efliciency.
  • a radio receiver of the type including a radio frequency amplifier network, a demodulator, an audio frequency amplifier network and a reproducer, means responsive to variations in modulated signal carrier amplitude for automatically controlling the carrier transmission efiiciency through the radio amplifier network in a sense to maintain the carrier amplitude at the demodulator input substantially uniform regardless of fading at the radio amplifier network input, additional means, responsive to an increase in the audio component amplitude of the modulated signal carrier, for increasing the said transmission efiiciency, said first means including a carrier rectifier, and said additional means including a rectifier for said audio component.
  • a radio receiver of the type including a radio frequency amplifier network, a demodulator, an audio frequency amplifier network and a reproducer, means responsive to variations in modulated signal carrier amplitude for automatically controlling the carrier transmission efficiency through the radio amplifier network in a sense to maintain the carrier amplitude at the demodulator input substantially uniform regardless of fading at the radio amplifier network input, additional means, responsive to an increase in the audio component amplitude of the modulated signal carrier, for increasing the said transmission efiiciency, said first means including a rectifier upon whose input is impressed modulated carrier energy, and said additional means deriving its audio component input from said rectifier output.
  • a radio receiver of the type including a radio frequency amplifier network, a demodulator, an audio frequency amplifier network and a reproducer, means responsive to variations in modulated signal carrier amplitude for automatically controlling the carrier transmission efiiciency through the radio amplifier network in a sense to maintain the carrier amplitude at the demodulator input substantially uniform regardless of fading at the radio amplifier network input, additional means, responsive to an increase in the audio component amplitude of the modulated signal carrier, for increasing the said transmission eificiency, said radio amplifier network comprising at least two amplifier stages in cascade, said first means controlling the gain of the first stage, and said additional means controlling the gain of the second stage.

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  • Control Of Amplification And Gain Control (AREA)
  • Amplifiers (AREA)
  • Circuits Of Receivers In General (AREA)
US100069A 1935-09-10 1936-09-10 Automatic gain control circuits Expired - Lifetime US2112279A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE2112279X 1935-09-10
DE1935T0045801 DE691564C (de) 1935-09-10 1935-09-28 Empfaenger mit Dynamikregelung im Hochfrequenzteil

Publications (1)

Publication Number Publication Date
US2112279A true US2112279A (en) 1938-03-29

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Family Applications (2)

Application Number Title Priority Date Filing Date
US100069A Expired - Lifetime US2112279A (en) 1935-09-10 1936-09-10 Automatic gain control circuits
US100970A Expired - Lifetime US2179928A (en) 1935-09-10 1936-09-16 Receiver gain control circuits

Family Applications After (1)

Application Number Title Priority Date Filing Date
US100970A Expired - Lifetime US2179928A (en) 1935-09-10 1936-09-16 Receiver gain control circuits

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US (2) US2112279A (de)
DE (1) DE691564C (de)
FR (1) FR810230A (de)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2524985A (en) * 1946-03-26 1950-10-10 Olive S Petty Noise-level responsive amplifier
US2538772A (en) * 1943-04-20 1951-01-23 Sperry Corp Automatic volume control system
US2958048A (en) * 1957-06-14 1960-10-25 Atlantic Refining Co Automatic volume control for seismograph signal amplifier
EP0127792A2 (de) * 1983-06-01 1984-12-12 TELEFUNKEN Fernseh und Rundfunk GmbH Empfangsgerät
US4580288A (en) * 1982-03-22 1986-04-01 Telefunken Electronic Gmbh Receiver input circuit
US4776040A (en) * 1984-09-03 1988-10-04 Pioneer Electronic Corporation Superheterodyne receiver

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2484662A (en) * 1946-01-24 1949-10-11 Collins Radio Co Automatic acoustic control for public address systems and the like
US2944256A (en) * 1955-08-11 1960-07-05 Lockheed Aircraft Corp Radar aiming angle analyzer
US3023358A (en) * 1955-12-12 1962-02-27 Schlumberger Well Surv Corp Control systems
US4403348A (en) * 1981-09-21 1983-09-06 Bell Telephone Laboratories, Incorporated Single sideband receiver with intersyllabic gain correction limit control

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2538772A (en) * 1943-04-20 1951-01-23 Sperry Corp Automatic volume control system
US2524985A (en) * 1946-03-26 1950-10-10 Olive S Petty Noise-level responsive amplifier
US2958048A (en) * 1957-06-14 1960-10-25 Atlantic Refining Co Automatic volume control for seismograph signal amplifier
US4580288A (en) * 1982-03-22 1986-04-01 Telefunken Electronic Gmbh Receiver input circuit
EP0127792A2 (de) * 1983-06-01 1984-12-12 TELEFUNKEN Fernseh und Rundfunk GmbH Empfangsgerät
EP0127792A3 (en) * 1983-06-01 1986-01-22 Telefunken Fernseh Und Rundfunk Gmbh Receiver
US4776040A (en) * 1984-09-03 1988-10-04 Pioneer Electronic Corporation Superheterodyne receiver

Also Published As

Publication number Publication date
DE691564C (de) 1940-05-30
FR810230A (fr) 1937-03-18
US2179928A (en) 1939-11-14

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