Patent ID: 6430238
Filing Date: 2002-08-06
Classification: G11B,H04L

Abstract:
Digital servo apparatus comprising:a programmable gain amplifier having a first input for receiving an analog input signal and having a second input for receiving a gain control signal to produce an amplified analog signal indicative of the analog input signal and the gain control signal; a converter coupled to receive the amplified analog signal for producing a digital representation thereof; a differentiating filter coupled to receive the digital representation of the amplified analog signal for producing therefrom a differentiated filtered signal; an interpolator coupled to receive the differentiated filtered signal for producing therefrom a plurality of outputs, each representative of the differentiated filtered signal at a different sampling time; a summing circuit coupled to receive the plurality of outputs for producing therefrom an output signal indicative of the absolute values of the plurality of outputs; and a control circuit coupled to receive the output signal produced by the summing circuit for supplying a representative gain control signal to the second input of the programmable gain amplifier to alter the gain thereof.