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
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.
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)
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 |
-
1969
- 1969-02-28 DE DE19691910185 patent/DE1910185A1/en active Pending
-
1970
- 1970-02-26 GB GB1290578D patent/GB1290578A/en not_active Expired
- 1970-02-27 ES ES376994A patent/ES376994A1/en not_active Expired
- 1970-02-27 FR FR7007124A patent/FR2049045B2/fr not_active Expired
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 |