公开(公告)号：US3823379A

公开(公告)日：1974-07-09

申请号：US36264473

申请日：1973-05-21

Applicant: RCA CORP

Inventor： GEORGE J

IPC: H03G3/30 ,  H04B1/16 ,  H04N5/52

CPC classification number: H03G3/3068

Abstract: A television automatic gain control circuit which transforms the low input impedance of the gain control terminal of a stage such as a grounded base bipolar transistor RF amplifier of a UHF tuner or a PIN diode attenuator utilized for tuner gain reduction to an impedance comparable to that of the impedance of the gain control terminal of an MOS/FET transistor used as an RF amplifier of a VHF tuner. Additionally, the control circuit provides for clamping of the AGC voltage at a selected level to provide AGC delay different from VHF AGC delay. Also, a predetermined voltage offset is provided to translate the AGC voltage applied to the RF amplifier of the VHF tuner before being applied to the gain controlled stage of the UHF tuner.

公开(公告)号：US3766313A

公开(公告)日：1973-10-16

申请号：US3766313D

申请日：1972-08-07

Applicant: RCA CORP

Inventor： CARLSON D ,  GEORGE J

IPC: G06F3/153 ,  G06F15/02 ,  G09G5/00 ,  H04N5/00 ,  H04N5/38 ,  H03C1/14 ,  G06F3/14 ,  H04N5/40

CPC classification number: G06F15/02

Abstract: A desk top calculator or other generator of digitized video signals is coupled to the antenna terminals of a conventional television receiver. A circuit within the generator translates the digitized video signals into a modulated TV R-F picture carrier. The circuit includes a radio-frequency source, and a network of diode switchable attenuators. The latter are operated in response to control signals for switching the radio-frequency signal between three discrete levels. Two of the levels are for the display of black and white, respectively, and the third level is a ''''blacker than black'''' synchronization level.

Abstract translation: 数字化视频信号的桌面计算器或其它发生器耦合到常规电视接收机的天线端子。 发生器内的电路将数字化的视频信号转换成调制的TV R-F图像载体。 该电路包括射频源和二极管可切换衰减器的网络。 后者响应用于在三个离散电平之间切换射频信号的控制信号来操作。 其中两个级别分别用于显示黑白，第三级是“黑色比黑色”同步级别。