Log-exponential AGC circuit
AssigneeThe United States of America as represented by the Secretary of the Navy
InventorDennis W. Ricker
Life of this patent
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Abstract
An AGC circuit designed to have a response-time independent of the absolute ackground input level comprising a variable-gain amplifier, an envelope detector receiving an input from the variable-gain amplifier, a logarithmic amplifier to convert the envelope value to its logarithm, a summer to subtract this envelope from a reference and thus generate an error signal, an integrator to integrate the error signal, and an exponential converter to convert this signal to an exponential and apply it as a control signal to the variable-gain amplifier. Thus, a uniform echo pulse may be presented to a display regardless of the background level.
Claims4
A non-linear, automatic-gain-control circuit comprising:
- variable-gain amplifier means to which an input signal is applied;
- envelope-detecting means for detecting the envelope of the output from said variable-gain amplifier means;
- means for converting the envelope value to its logarithmic value;
- means for generating an integrated error signal from said logarithmic envelope;
- means for converting this error signal to its exponential value and applying this signal to said variable-gain amplifier for controlling the gain of said amplifier.
Dependencies are inferred from the claim text.