JPS55127716A - Narrow-band squelch circuit - Google Patents

Narrow-band squelch circuit

Info

Publication number
JPS55127716A
JPS55127716A JP3529479A JP3529479A JPS55127716A JP S55127716 A JPS55127716 A JP S55127716A JP 3529479 A JP3529479 A JP 3529479A JP 3529479 A JP3529479 A JP 3529479A JP S55127716 A JPS55127716 A JP S55127716A
Authority
JP
Japan
Prior art keywords
output
controller
amplifier
filter
signal
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
JP3529479A
Other languages
Japanese (ja)
Inventor
Koki Terui
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.)
NEC Corp
Original Assignee
NEC Corp
Nippon 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 NEC Corp, Nippon Electric Co Ltd filed Critical NEC Corp
Priority to JP3529479A priority Critical patent/JPS55127716A/en
Publication of JPS55127716A publication Critical patent/JPS55127716A/en
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G3/00—Gain control in amplifiers or frequency changers
    • H03G3/20—Automatic control
    • H03G3/30—Automatic control in amplifiers having semiconductor devices
    • H03G3/34—Muting amplifier when no signal is present or when only weak signals are present, or caused by the presence of noise signals, e.g. squelch systems

Landscapes

  • Control Of Amplification And Gain Control (AREA)
  • Noise Elimination (AREA)

Abstract

PURPOSE:To prevent erroneous operations of a squelch by detecting directly a signal through no filter for the standard input electric field and by detecting the signal through a filter if the input electric field is lowered. CONSTITUTION:The signal branched by coupler 13 is detected by detector 14 and is amplified by operational amplifier 15 and is inputted to voltage controller 16. When the output of detector 14 is a prescribed level or less, controller 16 applies a reverse bias voltage to diode 17. At this time, the signal passing through amplifier 16 is reflected by terminal a, and the output appears at terminal c. This output has the interference wave eliminated by filter 21 and is detected by detection circuit 24 through forward-biased diode 22. When the output of filter 14 is the prescribed level or more, controller 16 gives a forward bias voltage to diode 17, and therefore, the output of amplifier 19 is outputted to terminal a and is detected by detection circuit 24 through forward-biased diode 23. This output is given to controller 26 through the amplifier, and the output of controller 26 operates intermediate frequency amplifier 27 as a squelch switch.
JP3529479A 1979-03-26 1979-03-26 Narrow-band squelch circuit Pending JPS55127716A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP3529479A JPS55127716A (en) 1979-03-26 1979-03-26 Narrow-band squelch circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP3529479A JPS55127716A (en) 1979-03-26 1979-03-26 Narrow-band squelch circuit

Publications (1)

Publication Number Publication Date
JPS55127716A true JPS55127716A (en) 1980-10-02

Family

ID=12437746

Family Applications (1)

Application Number Title Priority Date Filing Date
JP3529479A Pending JPS55127716A (en) 1979-03-26 1979-03-26 Narrow-band squelch circuit

Country Status (1)

Country Link
JP (1) JPS55127716A (en)

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