JPS55115749A - Squelch circuit - Google Patents

Squelch circuit

Info

Publication number
JPS55115749A
JPS55115749A JP2300279A JP2300279A JPS55115749A JP S55115749 A JPS55115749 A JP S55115749A JP 2300279 A JP2300279 A JP 2300279A JP 2300279 A JP2300279 A JP 2300279A JP S55115749 A JPS55115749 A JP S55115749A
Authority
JP
Japan
Prior art keywords
impedance
squelch
diode
voltage
state
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
JP2300279A
Other languages
Japanese (ja)
Inventor
Mitsutaka Tsukuni
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 JP2300279A priority Critical patent/JPS55115749A/en
Publication of JPS55115749A publication Critical patent/JPS55115749A/en
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/06—Receivers
    • H04B1/10—Means associated with receiver for limiting or suppressing noise or interference

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Noise Elimination (AREA)

Abstract

PURPOSE:To make equal the detection voltage of the detection circuit in the squelch and normal states, by the equal impedance for the squelch circuit in the both states. CONSTITUTION:In the normal state when the equelch switch 21 is ON, the transistor Tr14 is in operating state and a given negative voltage is produced to the emitter. Thus, a given back bias is fed to the varactor diode 38, the capacitance of the diode 38 is low and high impedance is caused. In the squelch state when the squelch switch 21 is OFF, no collector current of Tr14 flows and the emitter voltage is the same level as the negative power supply voltage. But since the cathode side of the diode 38 is open in DC, no back bias voltage is applied and the diode 38 is at high capacitance. The load impedance viewed from the capacitor 13 is determined with the impedance of Tr14 in normal state and determined with the impedance of the diode 38 in squelch state. The constant is selected to obtain equal impedance for the both states.
JP2300279A 1979-02-27 1979-02-27 Squelch circuit Pending JPS55115749A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2300279A JPS55115749A (en) 1979-02-27 1979-02-27 Squelch circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2300279A JPS55115749A (en) 1979-02-27 1979-02-27 Squelch circuit

Publications (1)

Publication Number Publication Date
JPS55115749A true JPS55115749A (en) 1980-09-05

Family

ID=12098287

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2300279A Pending JPS55115749A (en) 1979-02-27 1979-02-27 Squelch circuit

Country Status (1)

Country Link
JP (1) JPS55115749A (en)

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