GB1290578A - - Google Patents

Info

Publication number
GB1290578A
GB1290578A GB1290578DA GB1290578A GB 1290578 A GB1290578 A GB 1290578A GB 1290578D A GB1290578D A GB 1290578DA GB 1290578 A GB1290578 A GB 1290578A
Authority
GB
United Kingdom
Prior art keywords
signal
discriminator
frequency
output
tuned
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.)
Expired
Application number
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 filed Critical
Publication of GB1290578A publication Critical patent/GB1290578A/en
Expired 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

  • Noise Elimination (AREA)
  • Circuits Of Receivers In General (AREA)
  • Channel Selection Circuits, Automatic Tuning Circuits (AREA)
  • Superheterodyne Receivers (AREA)
  • Television Receiver Circuits (AREA)

Abstract

1290578 Muting radio receivers INTERNATIONAL STANDARD ELECTRIC CORP 26 Feb 1970 [28 Feb 1969] 9269/70 Addition to 1238608 Heading H3T The invention relates to a muting arrangement for a frequency modulation receiver, in which, as in the parent Specification, the overall response prior to a frequency discriminator is made unsymmetrical relative to the signal frequency: the frequency discriminator produces a different D.C. output according to whether a signal or only noise is being received, and these two different D.C. outputs are used to mute and unmute an audio stage of the receiver. An embodiment comprises R.F. tuned circuit 9, frequency changer 10 and local oscillator 11, I.F. amplifier 12, limiter 13 and discriminator 14 of the integrator type: the R.F. tuned circuit 9 is mis-tuned away from the signal frequency. so that discriminator 14 produces zero D.C. output on noise and a D.C. output voltage U D on signal. The following audio stage 15 to which discriminator 14 is direct-coupled is then biased to cut off in the absence of a signal, but the D.C. output voltage U D biases it conductive for a signal. According to the present invention, . R.F. circuit 9 is tuned by means of a varactor diode 6 to which the D.C. output of the discriminator 14 is applied and so biases the diode as to resonate the circuit 9 when a signal is received.
GB1290578D 1969-02-28 1970-02-26 Expired GB1290578A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19691910185 DE1910185A1 (en) 1969-02-28 1969-02-28 Automatic squelch for an FM receiver

Publications (1)

Publication Number Publication Date
GB1290578A true GB1290578A (en) 1972-09-27

Family

ID=5726658

Family Applications (1)

Application Number Title Priority Date Filing Date
GB1290578D Expired GB1290578A (en) 1969-02-28 1970-02-26

Country Status (4)

Country Link
DE (1) DE1910185A1 (en)
ES (1) ES376994A1 (en)
FR (1) FR2049045B2 (en)
GB (1) GB1290578A (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3244983C2 (en) * 1982-12-04 1986-09-04 Interessengemeinschaft für Rundfunkschutzrechte GmbH Schutzrechtsverwertung & Co KG, 4000 Düsseldorf Circuit arrangement on a television set with multi-channel sound reproduction

Also Published As

Publication number Publication date
FR2049045B2 (en) 1973-03-16
DE1910185A1 (en) 1970-09-17
FR2049045A2 (en) 1971-03-26
ES376994A1 (en) 1972-05-16

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Legal Events

Date Code Title Description
PS Patent sealed
PLNP Patent lapsed through nonpayment of renewal fees