Automatic gain control utilizing controlled sampling

Claim 2

In an automatic control system, which includes a circuit having a controllable gain characteristic, a circuit for developing a gain control voltage which comprises, a trigger circuit having an input and an output, said trigger circuit having a predetermined trigger threshold level and being responsive to an applied signal for generating a pulsating signal having a substantially constant amplitude and a duty cycle proportional to the amplitude of said applied signal, means in circuit relationship with the output of said trigger circuit for developing a control voltage having an amplitude proportional to the duty cycle of said pulsating signal, and switching means in circuit relationship with said control voltage developing means and the output of said trigger circuit for selectively supplying a discharge paTh to said control voltage means for a predetermined interval only after the termination of each pulse of said pulsating signal to adjust the amplitude of said control voltage.

Claim 3

A circuit as defined in claim 1 wherein said control voltage developing means includes a capacitor having a predetermined capacitance value and a serial connection of a unidirectional conduction element and resistor means having a predetermined resistance value, said serial connection being in circuit with the output of said trigger circuit and said capacitor, and wherein said discharge path has a predetermined time constant.

Claim 4

A circuit as defined in claim 2 wherein said switching means includes a monostable multivibrator responsive to the trailing edge of each pulse of said pulsating signal.

Claim 5

A pulse burst signal automatic gain control circuit which comprises, an amplifier having a controllable gain characteristic for stabilizing the amplitude of an applied burst signal, a trigger circuit having an input and an output, the input of said trigger circuit being in circuit relationship with said amplifier, said trigger circuit having a predetermined threshold level and being responsive to said burst signal for generating a pulsating signal having a substantially constant amplitude and a duty cycle proportional to the amplitude of said burst signal, means in circuit relationship with the output of said trigger circuit for developing a control voltage having an amplitude proportional to the duty cycle of said pulsating signal, means for supplying said control voltage to said amplifier for controlling the gain of said amplifier, and controllable switching means in circuit relationship with said control voltage developing means and responsive to said pulsating signal for selectively supplying a discharge path to said control voltage developing means for a predetermined interval in accordance with a predetermined criterion related to individual pulses of said pulsating signal to adjust the amplitude of said control voltage.

Claim 6

A pulse burst signal automatic gain control circuit which comprises, an amplifier having a controllable gain characteristic for stabilizing the amplitude of an applied burst signal, a trigger circuit having an input and an output, the input of said trigger circuit being in circuit relationship with said amplifier, said trigger circuit having a predetermined threshold level and being responsive to said burst signal for generating a pulsating signal having a substantially constant amplitude and a duty cycle proportional to the amplitude of said burst signal, means in circuit relationship with the output of said trigger circuit for developing a control voltage having an amplitude proportional to the duty cycle of said pulsating signal, means for supplying said control voltage to said amplifier for controlling the gain of said amplifier, and controllable switching means in circuit relationship with said control voltage developing means and responsive to said pulsating signal for selectively supplying a discharge path to said control voltage developing means for a predetermined interval in accordance with a predetermined criterion related to individual pulses of said pulsating signal to adjust the amplitude of said control voltage.

Claim 7

A circuit as defined in claim 4 wherein said control voltage developing means includes a capacitor.

Claim 8

A circuit as defined in claim 5 wherein said controllable switching means includes a monostable multivibrator responsive to said pulsating signal to supply a discharge path for said capacitor in accordance with said predetermined criterion.

Claim 9

A circuit as defined in claim 6 wherein said multivibrator includes a normally ON transistor and a normally OFF transistor, each having collector, emitter and base terminals, said collector terminal of said normally OFF transistor being connected in circuit relationship with said capacitor means for supplying a discharge circuit path to said capacitor for a preestablished interval.

Claim 10

A circuit as defined in claim 7 further including means for triggering said monostable multivibrator only at the trailing edge of each pulse of said pulsating signal.

Claim 11

A circuit as defined in claim 8 wherein said control voltage developing means further includes unidirectional conduction means and resistor means forming a unidirectional charging path for said capacitor having a predetermined time-constant and wherein said discharge path includes resistor means to establish a predetermined discharge time-constant.