Automatic gain control video amplifier

Claim 2

An electronic automatic gain control device, comprising: input means for receiving an input signal; channel separation means for diverting said signal into first and second channels; gain varying means in said first channel for varying the gain of said signal in said first channel; means for recombining the signal on each of said channels so that a portion of the combined signal is from each of said channels; output means for receiving said combined signal; and feedback means connected between said output means and said gain varying means for automatically controlling the gain of that portion of said combined signal derived from said first channel.

Claim 3

The device of claim 1 wherein said means for recombining the signal on each of said channels is a switch that permits passage of only predetermined portions of the signal on each channel.

Claim 4

The device of claim 1 wherein said feedback means includes peak-white to peak-black detection means for producing a DC control voltage that is coupled back to said gain varying means to control the gain thereof.

Claim 5

An electronic gain control device, comprising: input means for receiving an input signal; channel separation means for diverting said signal into first and second channels; means for establishing substantially unity gain in said first channel; gain varying means for varying the gain of said signal in said second channel; means for recombining the signal on each of said channels so that a portion of the combined signal is from each of said channels; output means for receiving said combined signal; and feedback means connected between said output means and said gain varying means for controlling the gain of that portion of said combined signal from said second channel without affecting the substantially unity gain of that portion of said combined signal from said first channel.

Claim 6

An electronic gain control device, comprising: input means for receiving an input signal; channel separation means for diverting said signal into first and second channels; means for establishing substantially unity gain in said first channel; gain varying means for varying the gain of said signal in said second channel; means for recombining the signal on each of said channels so that a portion of the combined signal is from each of said channels; output means for receiving said combined signal; and feedback means connected between said output means and said gain varying means for controlling the gain of that portion of said combined signal from said second channel without affecting the substantially unity gain of that portion of said combined signal from said first channel.

Claim 7

The device of claim 4 wherein said signal is a television video signal and wherein the blanking interval of said signal is coupled through said first channel and the active video of said signal is coupled through said second channel.

Claim 8

The device of claim 5 wherein sync pulses and color burst are coupled through said first channel to thereby hold the same at substantially unity gain.

Claim 9

An electronic automatic gain control device, comprising: input means for receiving an input signal; channel separation means for diverting said signal into first and second channels; gain varying means in said first channel for varying the gain of said signal in said first channel; means for recombining the signal on each of said channels so that a portion of the combined signal is from each of said channels; output means for receiving said combined signal; feedback means connected between said output means and said gain varying means for automatically controlliNg the gain of that portion of said combined signal derived from said first channel; sensing means for sensing absence of an input signal of predetermined minimum magnitude; and means connected with said sensing means for disrupting gain controlling feedback from said output means to said gain varying means when said input signal is less than said predetermined magnitude.

Claim 10

An electronic automatic gain control device, comprising: input means for receiving an input signal; channel separation means for diverting said signal into first and second channels; gain varying means in said first channel for varying the gain of said signal in said first channel; means for recombining the signal on each of said channels so that a portion of the combined signal is from each of said channels; output means for receiving said combined signal; feedback means connected between said output means and said gain varying means for automatically controlliNg the gain of that portion of said combined signal derived from said first channel; sensing means for sensing absence of an input signal of predetermined minimum magnitude; and means connected with said sensing means for disrupting gain controlling feedback from said output means to said gain varying means when said input signal is less than said predetermined magnitude.

Claim 11

The device of claim 7 further characterized by preset unity gain means, and wherein said last named means connects said gain varying means with said preset unity gain means whenever feedback to said gain varying means from said output means is disrupted.

Claim 12

The device of claim 7 wherein said sensing means includes a fade detector the output of which energized switch actuating relay means, said relay controlled switch being connected in said feedback path.

Claim 13

An electric signal control device, comprising: input means for receiving an input signal; DC restoration means for receiving said input signals; output means for receiving said signal from said DC restoration means; feedback means connected between said output means and said DC restoration means for automatically controlling the setup level of said signal; channel separation means for dividing said signal into two channels one of which includes said DC restoration means; and means for recombining the signal on each said channel and coupling said combined signal to said output means, said combined signal including a portion of the signal on each said channel.

Claim 14

An electric signal control device, comprising: input means for receiving an input signal; DC restoration means for receiving said input signals; output means for receiving said signal from said DC restoration means; feedback means connected between said output means and said DC restoration means for automatically controlling the setup level of said signal; channel separation means for dividing said signal into two channels one of which includes said DC restoration means; and means for recombining the signal on each said channel and coupling said combined signal to said output means, said combined signal including a portion of the signal on each said channel.

Claim 15

The device of claim 10, wherein said other channel also includes DC restoration means, and wherein said feedback is coupled to both of said DC restoration means.

Claim 16

An electronic signal control device, comprising: input means for receiving an input signal; gain varying means for varying the gain of said signal; DC restoration means; first feedback means connected to said gain varying means for automatically controlling the gain of said signal; and second feedback means connected to said DC restoration means for controlling the setup level of said signal.

Claim 17

An electronic signal control device, comprising: input means for receiving an input signal; gain varying means for varying the gain of said signal; DC restoration means; first feedback means connected to said gain varying means for automatically controlling the gain of said signal; and second feedback means connected to said DC restoration means for controlling the setup level of said signal.

Claim 18

The device of claim 12 wherein said first feedback means includes a peak-white to peak-black detector and wherein said second feedback includes a setup detector.

Claim 19

The device of claim 12 wherein said DC restoration means includes means for sensing the DC level of said signal and varying the same in response to said signal from said second feedback means.

Claim 20

The device of claim 12 wherein said second feedback means includes means for causing a push-pull DC control voltage to be coupled to said DC restoration means.

Claim 21

An electronic signal control device, comprising: input means for receiving an input signal; channel separation means for diverting said signal into first and second channels; gain varying means for varying the gain of said signal on said first channel; DC restoration means in each of said channels; means for recombining the signal on each of said channels so that a portion of the combined signal is from each of said channels; output means for receiving said combined signal; first feedback means connected to said gain varying means for automatically controlling the gain of that portion of said combined signal derived from said first channel; and second feedback means connected to said DC restoration means for controlling the setup level of said combined signal.

Claim 22

An electronic signal control device, comprising: input means for receiving an input signal; channel separation means for diverting said signal into first and second channels; gain varying means for varying the gain of said signal on said first channel; DC restoration means in each of said channels; means for recombining the signal on each of said channels so that a portion of the combined signal is from each of said channels; output means for receiving said combined signal; first feedback means connected to said gain varying means for automatically controlling the gain of that portion of said combined signal derived from said first channel; and second feedback means connected to said DC restoration means for controlling the setup level of said combined signal.

Claim 23

The device of claim 16 wherein the signal in said second channel is held to substantially unity gain and wherein said means for recombining the signal on each of said channels includes switching means for passing only a predetermined portion of the signal on each of said channels.

Claim 24

An electronic signal control device, comprising: input means for receiving an input signal; channel separation means for diverting said signal into first and second channels; means for establishing subStantially unity gain in said first channel; gain varying means for varying the gain of said signal in said second channel; unity gain means; control means for detecting absence of an input signal of predetermined minimum magnitude; DC restoration means in each of said channels; switching means for recombining the signal on each of said channels so that a portion of the combined signal is from each of said channels; output means for receiving said combined signal; first feedback means connected between said output means and said gain varying means for automatically controlling the gain of that portion of the combined signal derived from said second channel, said feedback means including switch means controlled by said control means for disrupting feedback from said output means and connecting said gain varying means to said unity gain means when the input signal falls below said predetermined minimum magnitude; and second feedback means connected between said output means and said DC restoration means for controlling the setup of said combined signal.

Claim 25

An electronic signal control device, comprising: input means for receiving an input signal; channel separation means for diverting said signal into first and second channels; means for establishing subStantially unity gain in said first channel; gain varying means for varying the gain of said signal in said second channel; unity gain means; control means for detecting absence of an input signal of predetermined minimum magnitude; DC restoration means in each of said channels; switching means for recombining the signal on each of said channels so that a portion of the combined signal is from each of said channels; output means for receiving said combined signal; first feedback means connected between said output means and said gain varying means for automatically controlling the gain of that portion of the combined signal derived from said second channel, said feedback means including switch means controlled by said control means for disrupting feedback from said output means and connecting said gain varying means to said unity gain means when the input signal falls below said predetermined minimum magnitude; and second feedback means connected between said output means and said DC restoration means for controlling the setup of said combined signal.

Claim 26

The device of claim 18 further characterized by timing means connected to said switching means and said first and second feedback means for controlling selection of the combined signal from said first and second channels and selection of the portion of the combined signal sampled for feedback purposes.

Claim 27

The device of claim 19 further characterized by clamp means controlled by said timing means and establishing a DC level on said DC restoration means.

Claim 28

The device of claim 19 wherein said timing means produces control signals whereby the feedback to said first and second feedback means is sampled at different times.

Claim 29

An electronic video signal control device, comprising: input means for receiving a video input signal having a blanking interval and an active scan interval; means for separating said incoming signal into first and second channels; isolation amplifying means in said first channel, said signal in said first channel being held to substantially unity gain; attenuation means in said second channel; first DC restoration means in said first channel; second DC restoration means in said second channel; switching means connected to said first and second DC restoration means; output means connected to said switching means; switching control means for determining switching of said switching means between said first and second channels whereby the combined output signal includes the blanking interval from said first channel and the active video from said second channel; first feedback means connected between said output means and said attenuation means for automatically controlling the gain of the video signal in said second channel, said first feedback means including a switch; unity gain means; signal fade control means connected to receive said input signal and cause said switch in said first feedback means to disrupt said first feedback path and connect said attenuation means to said unity gain means whenever the level of said input video signal falls below a predetermined minimum value; second feedback means connected between said output means and said first and second DC restoration means for controlling the setup of said combined signal; and timing means for controlling said switching means and said first and second feedback means.

Claim 30

An electronic video signal control device, comprising: input means for receiving a video input signal having a blanking interval and an active scan interval; means for separating said incoming signal into first and second channels; isolation amplifying means in said first channel, said signal in said first channel being held to substantially unity gain; attenuation means in said second channel; first DC restoration means in said first channel; second DC restoration means in said second channel; switching means connected to said first and second DC restoration means; output means connected to said switching means; switching control means for determining switching of said switching means between said first and second channels whereby the combined output signal includes the blanking interval from said first channel and the active video from said second channel; first feedback means connected between said output means and said attenuation means for automatically controlling the gain of the video signal in said second channel, said first feedback means including a switch; unity gain means; signal fade control means connected to receive said input signal and cause said switch in said first feedback means to disrupt said first feedback path and connect said attenuation means to said unity gain means whenever the level of said input video signal falls below a predetermined minimum value; second feedback means connected between said output means and said first and second DC restoration means for controlling the setup of said combined signal; and timing means for controlling said switching means and said first and second feedback means.

Claim 31

The device of claim 22 wherein said first channel includes delay means to assure proper phasing of said signal s when combined by said switch means, and wherein said second channel includes compensation means for providing uniform signal delay regardless of attenuation of said attenuation means.

Claim 32

An electronic video signal control device, comprising: input means to receive a video broadcast signal having a blanking interval and an active scan interval; means for separating said incoming signal into first and second channels; isolation amplifying means in said first channel to establish substantially unity gain therein; attenuation means in said second channel for varying the gain of said signal therein; first DC restoration means in said first channel; second DC restoration means in said second channel; gating means for receiving said signals from said first and second channels and passing the blanking interval of the signal on said first channel and the active video of the signal on the second channel so that a combined output signal is produced; output means for receiving said combined output signal; a first detector connected with said output means for producing a DC signal corresponding to the active video peak-white DC level; a second detector connected with said output means for producing a DC signal corresponding to the active video peak-black DC level; a third detector connected with said output means for producing a DC signal corresponding to the video blanking DC level; means for receiving said DC signals from said first and second detectors and producing a DC signal that is coupled to said attenuation means to automatically control the gain of the signal in said second channel; means for receiving the output from said second detector and said third detector and producing DC signals that are coupled to said first and second DC restoration means, respectively, to automatically control setup of said combined output signal; timing means; and means connected between said timing means and said first, second and third detectors for causing sampling of said output signal at predetermined different times.

Claim 33

An electronic video signal control device, comprising: input means to receive a video broadcast signal having a blanking interval and an active scan interval; means for separating said incoming signal into first and second channels; isolation amplifying means in said first channel to establish substantially unity gain therein; attenuation means in said second channel for varying the gain of said signal therein; first DC restoration means in said first channel; second DC restoration means in said second channel; gating means for receiving said signals from said first and second channels and passing the blanking interval of the signal on said first channel and the active video of the signal on the second channel so that a combined output signal is produced; output means for receiving said combined output signal; a first detector connected with said output means for producing a DC signal corresponding to the active video peak-white DC level; a second detector connected with said output means for producing a DC signal corresponding to the active video peak-black DC level; a third detector connected with said output means for producing a DC signal corresponding to the video blanking DC level; means for receiving said DC signals from said first and second detectors and producing a DC signal that is coupled to said attenuation means to automatically control the gain of the signal in said second channel; means for receiving the output from said second detector and said third detector and producing DC signals that are coupled to said first and second DC restoration means, respectively, to automatically control setup of said combined output signal; timing means; and means connected between said timing means and said first, second and third detectors for causing sampling of said output signal at predetermined different times.