Patent ID: 6804073
Filing Date: 2004-10-12
Classification: G11B

Abstract:
An apparatus adapted to be responsive to a signal derived by a transducer, the signal having random fluctuations in amplitude due to anomalies in energy coupled to the transducer, the apparatus comprising:circuitry including: a signal input adapted to be responsive to the signal, a variable gain amplifier connected to be responsive to the signal input, and a signal output connected to be responsive to the variable gain amplifier, first and second circuits connected to be responsive to the signal output of the circuitry for respectively deriving first and second feedback signals for controlling the gain of the amplifier, the first circuit including an analog gain control circuit, the second circuit being arranged for causing the second feedback signal to have a series of constant values, each determined by the signal at the signal output of the circuitry during different successive time intervals, the first and second circuits and the variable gain amplifier being arranged so the first and second feedback signals can simultaneously affect the gain of the amplifier.