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JPS55100763A - Fm multiplex demodulator circuit - Google Patents

Fm multiplex demodulator circuit

Info

Publication number
JPS55100763A
JPS55100763A JP823779A JP823779A JPS55100763A JP S55100763 A JPS55100763 A JP S55100763A JP 823779 A JP823779 A JP 823779A JP 823779 A JP823779 A JP 823779A JP S55100763 A JPS55100763 A JP S55100763A
Authority
JP
Japan
Prior art keywords
signal
level
38khz
switching
base
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
JP823779A
Other languages
Japanese (ja)
Inventor
Masanori Ienaka
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.)
Hitachi Ltd
Original Assignee
Hitachi 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 Hitachi Ltd filed Critical Hitachi Ltd
Priority to JP823779A priority Critical patent/JPS55100763A/en
Priority to GB7941976A priority patent/GB2040145A/en
Priority to DE19792950485 priority patent/DE2950485A1/en
Priority to IT19515/80A priority patent/IT1149803B/en
Publication of JPS55100763A publication Critical patent/JPS55100763A/en
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04H—BROADCAST COMMUNICATION
    • H04H40/00—Arrangements specially adapted for receiving broadcast information
    • H04H40/18—Arrangements characterised by circuits or components specially adapted for receiving
    • H04H40/27—Arrangements characterised by circuits or components specially adapted for receiving specially adapted for broadcast systems covered by groups H04H20/53 - H04H20/95
    • H04H40/36—Arrangements characterised by circuits or components specially adapted for receiving specially adapted for broadcast systems covered by groups H04H20/53 - H04H20/95 specially adapted for stereophonic broadcast receiving
    • H04H40/45—Arrangements characterised by circuits or components specially adapted for receiving specially adapted for broadcast systems covered by groups H04H20/53 - H04H20/95 specially adapted for stereophonic broadcast receiving for FM stereophonic broadcast systems receiving
    • H04H40/72—Arrangements characterised by circuits or components specially adapted for receiving specially adapted for broadcast systems covered by groups H04H20/53 - H04H20/95 specially adapted for stereophonic broadcast receiving for FM stereophonic broadcast systems receiving for noise suppression
    • 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
    • H03G3/3005—Automatic control in amplifiers having semiconductor devices in amplifiers suitable for low-frequencies, e.g. audio amplifiers
    • 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
    • H04B1/16—Circuits
    • H04B1/1646—Circuits adapted for the reception of stereophonic signals
    • H04B1/1661—Reduction of noise by manipulation of the baseband composite stereophonic signal or the decoded left and right channels
    • H04B1/1669—Reduction of noise by manipulation of the baseband composite stereophonic signal or the decoded left and right channels of the demodulated composite stereo signal
    • H04B1/1676—Reduction of noise by manipulation of the baseband composite stereophonic signal or the decoded left and right channels of the demodulated composite stereo signal of the sum or difference signal

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Multimedia (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Stereo-Broadcasting Methods (AREA)

Abstract

PURPOSE: To prevent a noise level and the sense of an audio field from changing suddenly, by varying the level of a switching signal of 38kHz according to the intensity of an input electric field.
CONSTITUTION: A composite signal is applied to the base of transistor Q1, and a switching signal of 38kHz is also applied to switching circuit Q2 and Q3 and multiplied by the composite signal for stereo demodulation. Then, Q4, Q5 and Q6 are used to improve crosstalk. A signal obtained by rectifying an IF signal is applied to the base of Q9 connected to the common emitter of Q7 and Q8 applied with the 38kHz signal. The gains of Q7 and Q8 vary with the level of the IF signal and the level of the 38kHz signal is lowered right before an input level where a noise increases, so that the noise level of the subcarrier band can be reduced.
COPYRIGHT: (C)1980,JPO&Japio
JP823779A 1979-01-29 1979-01-29 Fm multiplex demodulator circuit Pending JPS55100763A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
JP823779A JPS55100763A (en) 1979-01-29 1979-01-29 Fm multiplex demodulator circuit
GB7941976A GB2040145A (en) 1979-01-29 1979-12-05 Improvements in F.M. receivers
DE19792950485 DE2950485A1 (en) 1979-01-29 1979-12-14 FM RECEIVER
IT19515/80A IT1149803B (en) 1979-01-29 1980-01-28 FM RECEIVER

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP823779A JPS55100763A (en) 1979-01-29 1979-01-29 Fm multiplex demodulator circuit

Publications (1)

Publication Number Publication Date
JPS55100763A true JPS55100763A (en) 1980-07-31

Family

ID=11687534

Family Applications (1)

Application Number Title Priority Date Filing Date
JP823779A Pending JPS55100763A (en) 1979-01-29 1979-01-29 Fm multiplex demodulator circuit

Country Status (4)

Country Link
JP (1) JPS55100763A (en)
DE (1) DE2950485A1 (en)
GB (1) GB2040145A (en)
IT (1) IT1149803B (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5646346A (en) * 1979-09-21 1981-04-27 Hitachi Ltd Control system for fm stereo demodulation
KR960008328B1 (en) * 1987-02-20 1996-06-24 상요덴기 가부시기가이샤 Fm/fmx stereophonic receiver

Also Published As

Publication number Publication date
DE2950485A1 (en) 1980-08-07
IT1149803B (en) 1986-12-10
GB2040145A (en) 1980-08-20
IT8019515A0 (en) 1980-01-28

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