JPS57155842A - Noise reduction circuit - Google Patents

Noise reduction circuit

Info

Publication number
JPS57155842A
JPS57155842A JP4203281A JP4203281A JPS57155842A JP S57155842 A JPS57155842 A JP S57155842A JP 4203281 A JP4203281 A JP 4203281A JP 4203281 A JP4203281 A JP 4203281A JP S57155842 A JPS57155842 A JP S57155842A
Authority
JP
Japan
Prior art keywords
signal
variable gain
input
reference signal
type variable
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.)
Pending
Application number
JP4203281A
Other languages
Japanese (ja)
Inventor
Tomoyuki Kawabata
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.)
Nippon Gakki Co Ltd
Original Assignee
Nippon Gakki 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 Nippon Gakki Co Ltd filed Critical Nippon Gakki Co Ltd
Priority to JP4203281A priority Critical patent/JPS57155842A/en
Publication of JPS57155842A publication Critical patent/JPS57155842A/en
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G7/00—Volume compression or expansion in amplifiers
    • H03G7/008—Control by a pilot signal

Landscapes

  • Networks Using Active Elements (AREA)
  • Reduction Or Emphasis Of Bandwidth Of Signals (AREA)

Abstract

PURPOSE:To prevent the decrease in the S/N at a minute input and the increase in distortion at a large input, by achieving a suitable signal level adjustment without any surplus or deficiency, through the compression or expanding control with a mixed reference signal. CONSTITUTION:An input signal Vi is applied to an adder 12 via a low pass filter 10 and an addition output signal Va with a reference signal VR from a reference high frequency signal oscillator 14 is added to a voltage control type variable gain amplifier 16. A control signal generated at a control signal generating circuit 18 based on the input signal Vi is applied to the voltage control type variable gain Va. An output signal Vc from a signal processing circuit 20 is applied to a voltage control type variable gain amplifier 22 and a reference signal component Ve is detected at a band pass filter 24 from the output signal Vd. This detected reference signal component Ve and the reference signal VR are applied to a level comparison circuit 26 to control the voltage control type variable gain amplifier 22 so that Ve=VR can be obtained from the result of comparison. The reference signal component Ve is subtracted from the output signal Vd to obtain an output signal Vo corresponding to the input signal Vi.
JP4203281A 1981-03-23 1981-03-23 Noise reduction circuit Pending JPS57155842A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP4203281A JPS57155842A (en) 1981-03-23 1981-03-23 Noise reduction circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP4203281A JPS57155842A (en) 1981-03-23 1981-03-23 Noise reduction circuit

Publications (1)

Publication Number Publication Date
JPS57155842A true JPS57155842A (en) 1982-09-27

Family

ID=12624818

Family Applications (1)

Application Number Title Priority Date Filing Date
JP4203281A Pending JPS57155842A (en) 1981-03-23 1981-03-23 Noise reduction circuit

Country Status (1)

Country Link
JP (1) JPS57155842A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0514813A2 (en) * 1991-05-21 1992-11-25 Nec Corporation Mobile telephone device wherein an adder supplies a sum of audio and out-of audio band signals to a compressor circuit

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS50122812A (en) * 1974-03-15 1975-09-26

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS50122812A (en) * 1974-03-15 1975-09-26

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0514813A2 (en) * 1991-05-21 1992-11-25 Nec Corporation Mobile telephone device wherein an adder supplies a sum of audio and out-of audio band signals to a compressor circuit
US5640685A (en) * 1991-05-21 1997-06-17 Nec Corporation Mobile telephone device wherein an adder supplies a sum of audio and out-of audio band signals to a compressor circuit

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