JPS56117433A - Muting circuit - Google Patents

Muting circuit

Info

Publication number
JPS56117433A
JPS56117433A JP2055680A JP2055680A JPS56117433A JP S56117433 A JPS56117433 A JP S56117433A JP 2055680 A JP2055680 A JP 2055680A JP 2055680 A JP2055680 A JP 2055680A JP S56117433 A JPS56117433 A JP S56117433A
Authority
JP
Japan
Prior art keywords
signal
channel selection
switch
muting
keyboard
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
JP2055680A
Other languages
Japanese (ja)
Inventor
Masaru Takeshita
Kazuhiko Hirabayashi
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 Home Electronics Ltd
NEC Corp
Original Assignee
NEC Home Electronics Ltd
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 Home Electronics Ltd, Nippon Electric Co Ltd filed Critical NEC Home Electronics Ltd
Priority to JP2055680A priority Critical patent/JPS56117433A/en
Publication of JPS56117433A publication Critical patent/JPS56117433A/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 obtain a muting circuit which is capable of a steady operation even for the multiplex bands, by operating a muting action by making use of the latch pulse produced by an alteration of the programmable division ratio during a switch of channel selection. CONSTITUTION:The microcomputer 30 receives the signal S1 delivered in accordance with the operation of the keyboard 20, and then transmits the band switching signal S2 (corresponding to UHF or VHF) to the local oscillator 11. A channel selection switch is carried out based on the signal S2 and the tuning voltage Vt. The latch signal S5 is delivered from the computer 30 during a switch of channel selection and then supplied to the monostable multivibrator 42 of the muting circuit 40 to make the transistor 46 conduct for a certain time. Thus the working of the voice circuit 50 is discontinued. Accordingly, a silent state is secured for a certain time with push of the keyboard 20 to produce no noise.
JP2055680A 1980-02-22 1980-02-22 Muting circuit Pending JPS56117433A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2055680A JPS56117433A (en) 1980-02-22 1980-02-22 Muting circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2055680A JPS56117433A (en) 1980-02-22 1980-02-22 Muting circuit

Publications (1)

Publication Number Publication Date
JPS56117433A true JPS56117433A (en) 1981-09-14

Family

ID=12030425

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2055680A Pending JPS56117433A (en) 1980-02-22 1980-02-22 Muting circuit

Country Status (1)

Country Link
JP (1) JPS56117433A (en)

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS54128613A (en) * 1978-03-30 1979-10-05 Hitachi Ltd Muting circuit

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS54128613A (en) * 1978-03-30 1979-10-05 Hitachi Ltd Muting circuit

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