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Title:
AUTOMATIC GAIN CONTROL CIRCUIT AND CATV SIGNAL DISTRIBUTING AMPLIFIER
Document Type and Number:
Japanese Patent JP2928055
Kind Code:
B2
Abstract:

PURPOSE: To set a large sum total of electric power of all transmitted signals without causing any trouble of distortion and to ensure a satisfactory carrier/ noise ratio by controlling the gain of an amplifier in accordance with the detecting level of the preceding sum total of electric power.
CONSTITUTION: The sum total of electric power of all signals is detected by a total power detecting circuit 32 among some of output signals of a down variable amplifier 31, and this detecting value is sent to a comparing part 33. Thus the detecting value is compared at the part 33 with the standard value of total power set in an all-channel transmitting state. Based on the result of this comparison, a gain control part 34 outputs a gain control signal to the amplifier 31 in order to control the power at a device standard level. Receiving the gain control signal, the amplifier 31 controls its gain to ensure a satisfactory carrier/noise while keeping the distortion degree set by the total power under the standard level and then sets a high transmission level.


Inventors:
Yagishita, Yukio
Application Number:
JP1993000156659
Publication Date:
July 28, 1999
Filing Date:
June 28, 1993
Export Citation:
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Assignee:
NEC CORP
International Classes:
H03G3/20; H04B1/04; H04N5/00; H04N7/10; H04N21/61; H04N21/647; (IPC1-7): H04N7/10; H03G3/20; H04B1/04; H04H1/02; H04N5/00
Domestic Patent References:
JP5040262A
JP42294A
JP3174887A
JP2107012A
JP57152239A
JP50159652A
JP359771U
Attorney, Agent or Firm:
京本 直樹 (外2名)