WO2001060056A2 - Automatic gain control - Google Patents

Automatic gain control Download PDF

Info

Publication number
WO2001060056A2
WO2001060056A2 PCT/EP2001/001277 EP0101277W WO0160056A2 WO 2001060056 A2 WO2001060056 A2 WO 2001060056A2 EP 0101277 W EP0101277 W EP 0101277W WO 0160056 A2 WO0160056 A2 WO 0160056A2
Authority
WO
WIPO (PCT)
Prior art keywords
signals
agc
output signals
tuner
amplifier
Prior art date
Application number
PCT/EP2001/001277
Other languages
French (fr)
Other versions
WO2001060056A3 (en
Inventor
Alan C. L. Yeo
Kam C. Kwong
Mieu N. Pang
Hwee B. Tan
Original Assignee
Koninklijke Philips Electronics N.V.
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 Koninklijke Philips Electronics N.V. filed Critical Koninklijke Philips Electronics N.V.
Priority to EP01907503A priority Critical patent/EP1190568B1/en
Priority to JP2001557776A priority patent/JP2004508741A/en
Priority to US09/958,130 priority patent/US7002638B2/en
Priority to AT01907503T priority patent/ATE552650T1/en
Publication of WO2001060056A2 publication Critical patent/WO2001060056A2/en
Publication of WO2001060056A3 publication Critical patent/WO2001060056A3/en

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
    • H04N5/4446—IF amplifier circuits specially adapted for B&W TV
    • 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
    • H03G3/3052—Automatic control in amplifiers having semiconductor devices in bandpass amplifiers (H.F. or I.F.) or in frequency-changers used in a (super)heterodyne receiver
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
    • H04N5/60—Receiver circuitry for the reception of television signals according to analogue transmission standards for the sound signals

Definitions

  • the invention relates to a method and device for automatic gain control in receivers for both TV and FM radio.
  • WOA-94/06244 discloses a variable gain amplifier. Front-end portions of television receivers or video tape recorders are described, each of which uses separate intermediate-frequency (IF) amplifiers for the FM sound carrier and vestigial AM picture carrier. In each front end, the two IF amplifiers comprise matched cascade connections of the variable gain amplifiers with tracking automatic gain control (AGC).
  • the AGC signals are generated by an AGC detector supplied composite video signal from a video detector, which video detector responds to amplified IF signal supplied by the IF amplifier for the vestigial AM picture carrier.
  • This apparatus is not suitable for a receiver for both TV and FM radio, as in FM radio receipt mode the video detector does not receive TV signals on which AGC control signals can be based.
  • US-A-5, 144,439 discloses a mono FM radio in a television receiver which includes a single tuner for tuning both television signals and broadcast FM stations.
  • the tuner is operated at a fixed gain setting in FM reception mode.
  • an object of the invention to provide an automatic gain control for both TV reception and FM radio reception.
  • the invention provides an automatic gain control as defined in the independent claims.
  • Advantageous embodiments are defined in the dependent claims.
  • the TV and FM radio signals are controUably amplified to obtain amplifier output signals, the amplifier output signals are tuner processed to obtain tuner output signals, the tuner output signals are applied as control signals to the controllable amplifier, a bandwidth of a thus formed AGC loop being wide enough for a TV channel, and the tuner output signals are narrow-band filtered to obtain narrow-band filtered signals having a bandwidth substantially corresponding to a bandwidth of an FM radio channel.
  • FIG. 1 an embodiment of a receiver in accordance with the present invention
  • FIG. 2 a second embodiment of a receiver in accordance with the present invention.
  • antenna signals from an antenna A are applied to an AGC amplifier AGC-AMP, the output of which is applied to a cascade connection of an IF filter F, a mixer MIX and an IF amplifier IF-AMP.
  • An output of the IF amplifier IF -AMP is applied to a ceramic filter CF having an output connected to an FM sound demodulator IC FM Snd Dem.
  • a sound processor Snd Proc processes output signals of the FM sound demodulator IC FM Snd Dem to furnish (stereo) load-speaker signals to load-speakers L.
  • the output of the IF amplifier IF-AMP is also applied to a surface acoustic wave filter SAW having an output that is connected to a TV IF IC.
  • a TV processor TV Proc processes output signals of the TV IF IC to furnish (color) image signals to a TV display TVD.
  • the output of the IF amplifier IF-AMP is fed back to the AGC amplifier AGC as a tuner-internal AGC signal T-AGC.
  • a conventional AGC signal TV -AGC from the TV IF IC is also applied as a control signal to the AGC amplifier AGC.
  • an FM AGC signal from the FM sound processor IC FM Snd Proc is also applied as a control signal to the AGC amplifier AGC.
  • FM radio reception protection of the mixer MIX and IF amplifier IF- AMP is needed is needed because of the varying strength and proximity of adjacent FM channels.
  • Adjacent FM channels are 200 kHz apart as compared to 6, 7 or 8 MHz for TV. Since the RF bandwidth during FM reception is in the order of a few MHz, a wide-band predetermined AGC or software-selectable AGC is provided. The bandwidth of this wideband AGC is wide enough to cope with TV signals (intended for the TV IF IC). This wide- band AGC peeks at the IF before the ceramic filter CF that has a typical bandwidth of 200 kHz and based on a predetermined level decides to act or not. This prevents the tuner stages from overloading.
  • FIG. 2 shows a second embodiment of a receiver REC2 in accordance with the present invention.
  • the same elements as in figure 1 are denoted with corresponding reference numerals.
  • Antenna signals from an antenna A2 are applied to an AGC amplifier AGC- AMP2, the output of which is applied to a tuner unit TUNIT2.
  • the tuner unit TUNIT2 comprises for example the IF filter, mixer and IF amplifier as shown in figure 1.
  • the output of the tuner unit TUNIT2 is coupled to the output of the tuner TUN2 for supplying to both the sound demodulation and processing unit SDPU2 and the TV demodulation and processing unit TVDPU2 the output signals.
  • These two units are only given block schematic and can for example comprise the same elements as the corresponding parts in figure 1.
  • the output of the sound demodulation and processing unit SDPU2 is coupled to loudspeakers L2 and the output of the TV demodulation and processing unit TVDPU2 is coupled to a TV display TVD2.
  • the TV demodulation and processing unit TVDPU2 comprises further a control output for supplying a control signal TV AGC2 corresponding to the control signal as described in relation to figure 1.
  • This control signal is supplied to the tuner TUN2 to be a control signal for the AGC amplifier AGC-AMP2.
  • the AGC amplifier further receives an internal control signal TAGC2 which is the same or corresponding as in figure 1.
  • the difference with the tuner of this figure and the tuner TUN of figure 1 is that the control signal from the TV demodulation and processing unit TVDPU2 is now supplied to the AGC amplifier AGC-AMP2 via switching means ST2.
  • This switching means are controlled in such a way that during reception of FM radio signals the switch is open and during receiving TV signals switch is closed. In this way the undefinable output signal of the TV demodulation and processing unit TVDPU2 during reception of FM radio signals have no influence on the AGC amplifier AGC-AMP2. In this way the operation of the tuner and that of the receiver is further improved.

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Circuits Of Receivers In General (AREA)
  • Control Of Amplification And Gain Control (AREA)

Abstract

In a method of automatic gain control for both TV and FM radio signals, the TV and FM radio signals are controllably amplified (AGC-AMP) to obtain amplifier output signals, the amplifier output signals are tuner processed (F, MIX, IF-AMP) to obtain tuner output signals, the tuner output signals are applied as control signals (T-AGC) to the controllable amplifier (AGC-AMP), a bandwidth of a thus formed AGC loop being wide enough for a TV channel, and the tuner output signals are narrow-band filtered (CF) to obtain narrow-band filtered signals having a bandwidth substantially corresponding to a bandwidth of an FM radio channel.

Description

Automatic gain control.
The invention relates to a method and device for automatic gain control in receivers for both TV and FM radio.
WOA-94/06244 discloses a variable gain amplifier. Front-end portions of television receivers or video tape recorders are described, each of which uses separate intermediate-frequency (IF) amplifiers for the FM sound carrier and vestigial AM picture carrier. In each front end, the two IF amplifiers comprise matched cascade connections of the variable gain amplifiers with tracking automatic gain control (AGC). The AGC signals are generated by an AGC detector supplied composite video signal from a video detector, which video detector responds to amplified IF signal supplied by the IF amplifier for the vestigial AM picture carrier. This apparatus is not suitable for a receiver for both TV and FM radio, as in FM radio receipt mode the video detector does not receive TV signals on which AGC control signals can be based.
US-A-5, 144,439 discloses a mono FM radio in a television receiver which includes a single tuner for tuning both television signals and broadcast FM stations. The tuner is operated at a fixed gain setting in FM reception mode.
It is, inter alia, an object of the invention to provide an automatic gain control for both TV reception and FM radio reception. To this end, the invention provides an automatic gain control as defined in the independent claims. Advantageous embodiments are defined in the dependent claims.
In a method of automatic gain control for both TV and FM radio signals, the TV and FM radio signals are controUably amplified to obtain amplifier output signals, the amplifier output signals are tuner processed to obtain tuner output signals, the tuner output signals are applied as control signals to the controllable amplifier, a bandwidth of a thus formed AGC loop being wide enough for a TV channel, and the tuner output signals are narrow-band filtered to obtain narrow-band filtered signals having a bandwidth substantially corresponding to a bandwidth of an FM radio channel. These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. Herein shows:
Figure 1 an embodiment of a receiver in accordance with the present invention, and
Figure 2 a second embodiment of a receiver in accordance with the present invention.
In the drawing, antenna signals from an antenna A are applied to an AGC amplifier AGC-AMP, the output of which is applied to a cascade connection of an IF filter F, a mixer MIX and an IF amplifier IF-AMP. An output of the IF amplifier IF -AMP is applied to a ceramic filter CF having an output connected to an FM sound demodulator IC FM Snd Dem. A sound processor Snd Proc processes output signals of the FM sound demodulator IC FM Snd Dem to furnish (stereo) load-speaker signals to load-speakers L. The output of the IF amplifier IF-AMP is also applied to a surface acoustic wave filter SAW having an output that is connected to a TV IF IC. A TV processor TV Proc processes output signals of the TV IF IC to furnish (color) image signals to a TV display TVD.
The output of the IF amplifier IF-AMP is fed back to the AGC amplifier AGC as a tuner-internal AGC signal T-AGC. Optionally, a conventional AGC signal TV -AGC from the TV IF IC is also applied as a control signal to the AGC amplifier AGC. Optionally, an FM AGC signal from the FM sound processor IC FM Snd Proc is also applied as a control signal to the AGC amplifier AGC.
During FM radio reception, protection of the mixer MIX and IF amplifier IF- AMP is needed is needed because of the varying strength and proximity of adjacent FM channels. Adjacent FM channels are 200 kHz apart as compared to 6, 7 or 8 MHz for TV. Since the RF bandwidth during FM reception is in the order of a few MHz, a wide-band predetermined AGC or software-selectable AGC is provided. The bandwidth of this wideband AGC is wide enough to cope with TV signals (intended for the TV IF IC). This wide- band AGC peeks at the IF before the ceramic filter CF that has a typical bandwidth of 200 kHz and based on a predetermined level decides to act or not. This prevents the tuner stages from overloading.
The proposed tuner-internal wide-band AGC can be used together with the conventional TV AGC or instead of the conventional TV AGC. Figure 2 shows a second embodiment of a receiver REC2 in accordance with the present invention. The same elements as in figure 1 are denoted with corresponding reference numerals.
Antenna signals from an antenna A2 are applied to an AGC amplifier AGC- AMP2, the output of which is applied to a tuner unit TUNIT2. The tuner unit TUNIT2 comprises for example the IF filter, mixer and IF amplifier as shown in figure 1. The output of the tuner unit TUNIT2 is coupled to the output of the tuner TUN2 for supplying to both the sound demodulation and processing unit SDPU2 and the TV demodulation and processing unit TVDPU2 the output signals. These two units are only given block schematic and can for example comprise the same elements as the corresponding parts in figure 1. The output of the sound demodulation and processing unit SDPU2 is coupled to loudspeakers L2 and the output of the TV demodulation and processing unit TVDPU2 is coupled to a TV display TVD2.
The TV demodulation and processing unit TVDPU2 comprises further a control output for supplying a control signal TV AGC2 corresponding to the control signal as described in relation to figure 1. This control signal is supplied to the tuner TUN2 to be a control signal for the AGC amplifier AGC-AMP2. The AGC amplifier further receives an internal control signal TAGC2 which is the same or corresponding as in figure 1.
The difference with the tuner of this figure and the tuner TUN of figure 1 is that the control signal from the TV demodulation and processing unit TVDPU2 is now supplied to the AGC amplifier AGC-AMP2 via switching means ST2. This switching means are controlled in such a way that during reception of FM radio signals the switch is open and during receiving TV signals switch is closed. In this way the undefinable output signal of the TV demodulation and processing unit TVDPU2 during reception of FM radio signals have no influence on the AGC amplifier AGC-AMP2. In this way the operation of the tuner and that of the receiver is further improved.
It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps other than those listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention can be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the device claim enumerating several means, several of these means can be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

CLAIMS:
1. A method of automatic gain control for both TV and FM radio signals, the method comprising the steps of: controUably amplifying (AGC-AMP) the TV and FM radio signals to obtain amplifier output signals; tuner processing (F, MIX, IF-AMP) the amplifier output signals to obtain tuner output signals; and applying the tuner output signals as control signals (T-AGC) to the controUably amplifying step (AGC-AMP), a bandwidth of a thus formed AGC loop being wide enough for a TV channel.
2. A method as claimed in claim 1, further comprising the step of:
IF processing (SAW; TV IF) the tuner output signals to obtain further control signals (TV-AGC) for the controUably amplifying step (AGC-AMP).
3. A method according to claim 2, further comprising the step of coupling respectively decoupling the further control signals for the controUably amplifying step.
4. A method as claimed in claim 1, further comprising the steps of: narrow-band filtering (CF) the tuner output signals to obtain narrow-band filtered signals having a bandwidth substantially corresponding to a bandwidth of an FM radio channel, and
FM demodulating (FM Snd Dem) the tuner output signals to obtain further control signals (FM-AGC) for the controUably amplifying step (AGC-AMP).
5. A device for automatic gain control for both TV and FM radio signals, the device comprising: a controllable amplifier (AGC-AMP) for the TV and FM radio signals to obtain amplifier output signals; a tuner (F, MIX, IF-AMP) for processing the amplifier output signals to obtain tuner output signals; and means (T-AGC) for applying the tuner output signals as control signals to the controllable amplifier (AGC-AMP), a bandwidth of a thus formed AGC loop being wide enough for a TV channel.
6. A receiving apparatus for both TV and FM radio signals, the apparatus comprising: a device as claimed in claim 5; and IF processing means for processing the tuner output signals for obtaining further control signals for the controllable amplifier.
7. A receiving apparatus as claimed in claim 6 further comprising: a narrow-band filter (CF) for the tuner output signals to obtain narrow-band filtered signals having a bandwidth substantially corresponding to a bandwidth of an FM radio channel,
FM sound processing circuitry (FM Snd Dem, Snd Proc) to obtain load-speaker signals from the obtain narrow-band filtered signals; and image signal processing circuitry (SAW, TV IF, TV Proc) to obtain display signals from the tuner output signals.
8. A receiving apparatus as claimed in claim 6 further comprising: switching means for coupling respectively decoupling the further control signals to the controllable amplifier.
9. A display apparatus comprising: a receiving apparatus as claimed in claim 6; and an image display (TVD for displaying the display signals.
PCT/EP2001/001277 2000-02-08 2001-02-07 Automatic gain control WO2001060056A2 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
EP01907503A EP1190568B1 (en) 2000-02-08 2001-02-07 Automatic gain control
JP2001557776A JP2004508741A (en) 2000-03-27 2001-02-07 Automatic gain control
US09/958,130 US7002638B2 (en) 2000-02-08 2001-02-07 Automatic gain control
AT01907503T ATE552650T1 (en) 2000-02-08 2001-02-07 AUTOMATIC GAIN CONTROL

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
SGPCT/SG00/00018 2000-02-08
SG0000018 2000-02-08
SG2000017483 2000-03-27
SG200001748-3 2000-03-27

Publications (2)

Publication Number Publication Date
WO2001060056A2 true WO2001060056A2 (en) 2001-08-16
WO2001060056A3 WO2001060056A3 (en) 2002-01-31

Family

ID=58408791

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2001/001277 WO2001060056A2 (en) 2000-02-08 2001-02-07 Automatic gain control

Country Status (1)

Country Link
WO (1) WO2001060056A2 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1331811A1 (en) * 2002-01-24 2003-07-30 Koninklijke Philips Electronics N.V. Television receiver circuit

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0470504A2 (en) * 1990-08-06 1992-02-12 Thomson Consumer Electronics, Inc. Fixed RF AGC of a television tuner for FM reception in a television receiver
EP0472119A2 (en) * 1990-08-23 1992-02-26 Thomson Consumer Electronics, Inc. Interrupting the video IF signal path during FM radio mode in a television receiver
EP0512374A1 (en) * 1991-05-06 1992-11-11 THOMSON multimedia Audio level equalization of television sound, broadcast FM and national weather service FM radio signals

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0470504A2 (en) * 1990-08-06 1992-02-12 Thomson Consumer Electronics, Inc. Fixed RF AGC of a television tuner for FM reception in a television receiver
EP0472119A2 (en) * 1990-08-23 1992-02-26 Thomson Consumer Electronics, Inc. Interrupting the video IF signal path during FM radio mode in a television receiver
EP0512374A1 (en) * 1991-05-06 1992-11-11 THOMSON multimedia Audio level equalization of television sound, broadcast FM and national weather service FM radio signals

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1331811A1 (en) * 2002-01-24 2003-07-30 Koninklijke Philips Electronics N.V. Television receiver circuit
WO2003063473A1 (en) * 2002-01-24 2003-07-31 Koninklijke Philips Electronics N.V. Television receiver circuit

Also Published As

Publication number Publication date
WO2001060056A3 (en) 2002-01-31

Similar Documents

Publication Publication Date Title
EP0512374B1 (en) Audio level equalization of television sound, broadcast FM and national weather service FM radio signals
JPH08154061A (en) Broadcasting signal receiver
EP0417913B1 (en) Television receiver with circuits for recovering two audio signals
US7002638B2 (en) Automatic gain control
JP3175093B2 (en) Receiving machine
JPH05252468A (en) Television receiver
CA2034453C (en) Quasi-parallel if with shared saw filter
JP2005513903A (en) Automatic gain control for tuners
EP1190568B1 (en) Automatic gain control
EP1171998B1 (en) If signal processing apparatus
WO2001060056A2 (en) Automatic gain control
US7202910B1 (en) Signal processing apparatus
EP2055098A1 (en) Receiving apparatus
KR100286275B1 (en) Method of signal-processing on abnormal sound mode
JP3463359B2 (en) Antenna control device
JP2000224497A (en) Television receiver
JPH09312813A (en) Tv receiver for traveling object
JPH0564104A (en) Television receiver
JP3058377B2 (en) C / N detector
JP3118308B2 (en) Noise detection circuit
JP2983840B2 (en) Receiver
JP3837303B2 (en) Television receiver
JP3081196U (en) Broadcast receiver
JPH05304640A (en) Television receiver
KR20070040858A (en) Tuner auto-detecting channel selectively

Legal Events

Date Code Title Description
WWE Wipo information: entry into national phase

Ref document number: 01800171.8

Country of ref document: CN

AK Designated states

Kind code of ref document: A2

Designated state(s): CN JP KR US

AL Designated countries for regional patents

Kind code of ref document: A2

Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE TR

WWE Wipo information: entry into national phase

Ref document number: 2001907503

Country of ref document: EP

WWE Wipo information: entry into national phase

Ref document number: 09958130

Country of ref document: US

ENP Entry into the national phase in:

Ref document number: 2001 557776

Country of ref document: JP

Kind code of ref document: A

WWE Wipo information: entry into national phase

Ref document number: 1020017012719

Country of ref document: KR

121 Ep: the epo has been informed by wipo that ep was designated in this application
AK Designated states

Kind code of ref document: A3

Designated state(s): CN JP KR US

AL Designated countries for regional patents

Kind code of ref document: A3

Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE TR

WWP Wipo information: published in national office

Ref document number: 2001907503

Country of ref document: EP