GB1375284A - - Google Patents

Info

Publication number
GB1375284A
GB1375284A GB731872A GB731872A GB1375284A GB 1375284 A GB1375284 A GB 1375284A GB 731872 A GB731872 A GB 731872A GB 731872 A GB731872 A GB 731872A GB 1375284 A GB1375284 A GB 1375284A
Authority
GB
United Kingdom
Prior art keywords
amplifier
colour
control
linear
control voltage
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
GB731872A
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 GB1375284A publication Critical patent/GB1375284A/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N11/00—Colour television systems
    • H04N11/06—Transmission systems characterised by the manner in which the individual colour picture signal components are combined
    • H04N11/18—Transmission systems characterised by the manner in which the individual colour picture signal components are combined using simultaneous and sequential signals, e.g. SECAM-system
    • H04N11/186—Decoding means therefor
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G1/00—Details of arrangements for controlling amplification
    • H03G1/0005—Circuits characterised by the type of controlling devices operated by a controlling current or voltage signal
    • H03G1/0035—Circuits characterised by the type of controlling devices operated by a controlling current or voltage signal using continuously variable impedance elements
    • H03G1/0052—Circuits characterised by the type of controlling devices operated by a controlling current or voltage signal using continuously variable impedance elements using diodes

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Processing Of Color Television Signals (AREA)

Abstract

1375284 Gain control; colour television INTERNATIONAL STANDARD ELECTRIC CORP 17 Feb 1972 [23 Feb 1971] 7318/72 Headings H4R and H4F A TV colour saturation controlling amplifiee incorporates a PIN diode in its negative feedback whereby variation of a D.C. control signal applied to the amplifier is effective to vary thr r.f. resistance of the diode and thus the gain of the amplifier. In a SECAM colour TV receiver (Figs. 1, 2, not shown) such an amplifier is included between the limiter and the demodulator in each of the R-Y and B-Y channels following the SECAM switch so as to serve as a colour saturation regulator (colour contrast control). In a PAL receiver the amplifier is incorporated in the colour channel preceding the direct and delayed channels. In the Fig. 7 embodiment a grounded emitter transistor T1 is provided with a negative feedback path consisting of a resistor R4 in shunt with a capacitor C3 and a PIN diode. A resistor R5 and a capacitor C5 serve to decouple A.C. components from a D.C. control voltage source. +Ust. The relationships between diode resistance and (a) control voltage and (b) amplifier output voltage are both non-linear (Figs. 4 and 5, not shown) but since they are substantially complementary the output voltage/control voltage characteristic is linear (Fig. 6, not shown). In order to ensure a linear frequency response of the amplifier this is followed by another grounded emitter transistor T2 having a frequency correcting circuit R9, C4 in its feedback path. The output voltage/frequency characteristic at various values P of the D.C. control voltage are depicted in the figure.
GB731872A 1971-02-23 1972-02-17 Expired GB1375284A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19712108497 DE2108497A1 (en) 1971-02-23 1971-02-23 Gain control, especially for setting the color saturation of a SECAM receiver

Publications (1)

Publication Number Publication Date
GB1375284A true GB1375284A (en) 1974-11-27

Family

ID=5799541

Family Applications (1)

Application Number Title Priority Date Filing Date
GB731872A Expired GB1375284A (en) 1971-02-23 1972-02-17

Country Status (5)

Country Link
AU (1) AU470736B2 (en)
DE (1) DE2108497A1 (en)
FR (1) FR2126342B1 (en)
GB (1) GB1375284A (en)
ZA (1) ZA72885B (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4275362A (en) * 1979-03-16 1981-06-23 Rca Corporation Gain controlled amplifier using a pin diode

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB853870A (en) * 1957-04-17 1960-11-09 British Telecomm Res Ltd Improvements in or relating to amplifiers employing transistors
NZ157749A (en) * 1968-10-03

Also Published As

Publication number Publication date
AU470736B2 (en) 1976-03-25
FR2126342B1 (en) 1975-10-24
ZA72885B (en) 1972-10-25
AU3898372A (en) 1973-08-16
DE2108497A1 (en) 1972-09-07
FR2126342A1 (en) 1972-10-06

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Legal Events

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