JPS57113635A - Pilot agc system - Google Patents

Pilot agc system

Info

Publication number
JPS57113635A
JPS57113635A JP18749280A JP18749280A JPS57113635A JP S57113635 A JPS57113635 A JP S57113635A JP 18749280 A JP18749280 A JP 18749280A JP 18749280 A JP18749280 A JP 18749280A JP S57113635 A JPS57113635 A JP S57113635A
Authority
JP
Japan
Prior art keywords
level
pilot
restored
interrupted
gain
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
JP18749280A
Other languages
Japanese (ja)
Inventor
Toshio Ichikawa
Tatsuo Matsumoto
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.)
Fujitsu Ltd
Original Assignee
Fujitsu 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 Fujitsu Ltd filed Critical Fujitsu Ltd
Priority to JP18749280A priority Critical patent/JPS57113635A/en
Publication of JPS57113635A publication Critical patent/JPS57113635A/en
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B3/00—Line transmission systems
    • H04B3/02—Details
    • H04B3/04—Control of transmission; Equalising
    • H04B3/10—Control of transmission; Equalising by pilot signal

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Control Of Amplification And Gain Control (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)

Abstract

PURPOSE:To keep the AGC operation with the same degree as the preceding operation, even when one frequency is interrupted, by transmitting a plurality of pilot frequencies at all times. CONSTITUTION:When one of pilot frequency sources PF1, PF2 is interrupted, an output level of band pass filter BPF is rapidly lowered by 3dB, because the power is halved. This state is detected at a level detector DET and the gain of a DC amplifier AMP2 is controlled to restore it to the orginal state and the level is restored to the preceding value. The entire time constant of the AGC circuit is set longer so that the main signal level of the transmission line is not fluctuated. When a failure of a pilot frequency source is restored, the output of the amplifier AMP1 is increased for a short time. The gain of the amplifier AMP2 is lowered after the detection with a level detector DEC.
JP18749280A 1980-12-30 1980-12-30 Pilot agc system Pending JPS57113635A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP18749280A JPS57113635A (en) 1980-12-30 1980-12-30 Pilot agc system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP18749280A JPS57113635A (en) 1980-12-30 1980-12-30 Pilot agc system

Publications (1)

Publication Number Publication Date
JPS57113635A true JPS57113635A (en) 1982-07-15

Family

ID=16207003

Family Applications (1)

Application Number Title Priority Date Filing Date
JP18749280A Pending JPS57113635A (en) 1980-12-30 1980-12-30 Pilot agc system

Country Status (1)

Country Link
JP (1) JPS57113635A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60145713A (en) * 1984-01-10 1985-08-01 Fujitsu Ltd Automatic gain control system
US20100061569A1 (en) * 2008-09-11 2010-03-11 Seiko Epson Corporation Image display device, projector, control method, and information storage medium

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60145713A (en) * 1984-01-10 1985-08-01 Fujitsu Ltd Automatic gain control system
JPH0325048B2 (en) * 1984-01-10 1991-04-04 Fujitsu Ltd
US20100061569A1 (en) * 2008-09-11 2010-03-11 Seiko Epson Corporation Image display device, projector, control method, and information storage medium
US8520863B2 (en) * 2008-09-11 2013-08-27 Seiko Epson Corporation Image display device, projector, control method, and information storage medium

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