Gating network for a sampling circuit
AssigneeZenith Radio Corporation
InventorGopal K. Srivastava
Life of this patent
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Abstract
A gating network is described for enabling and disabling a conventional sampling circuit. The gating network includes a pulse generator which develops an enabling pulse in time synchronism with the signal to be sampled by the sampling circuit. The enabling pulse and the signal to be sampled are applied to an AND gate which develops a control signal whose duration is no longer than the signal to be sampled. The control signal is applied to the sampling circuit to enable its detection of the signal to be sampled.
Claims9
A gating network for selectively activating and deactivating a sampling circuit which receives an input signal having a sampling component to be sensed, comprising:
- a pulse generator for generating an enabling pulse which is in time synchronism with the sampling component;
- biasing means;
- an AND gate responsive to the enabling pulse and the signal containing the sampling component, the AND gate being biased by said biasing means such that it is responsive only to a sampling component of a selected amplitude so as to generate a control signal whose duration is shorter than both the sampling component and the enabling pulse;
- and
- means for coupling the control signal to the sampling circuit to enable the latter circuit in synchronism with the sampling component.
In a television receiver which develops a demodulated signal having a VIR color burst on line nineteen and standard color bursts on other lines, and which includes a sampling circuit to detect the amplitude of the demodulated VIR color burst, a gating network for activating the sampling circuit, comprising:
- a pulse generator for developing an enabling pulse in time synchronism with the VIR color burst and for developing additional enabling pulses in time synchronism with standard color bursts on selected lines preceding the VIR color burst;
- an AND gate responsive to the enabling pulses and the demodulated signal for developing control pulses whose durations are no longer than the durations of the color bursts;
- and
- means for coupling the control pulses to the sampling circuit to enable the latter circuit in synchronism with the color burst and the standard color bursts occurring during said selected lines.
Dependencies are inferred from the claim text.