Browse Prior Art Database

DC-Drift Compensation in Digital Signal Processing Systems

IP.com Disclosure Number: IPCOM000100467D
Original Publication Date: 1990-Apr-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 2 page(s) / 74K

Publishing Venue

IBM

Related People

Christopher, RJ: AUTHOR [+3]

Abstract

Disclosed is a method to compensate for time-varying DC-offsets in DC-coupled analog signals. The method is applicable in any digital signal-processing system that operates on signals which are bounded in time. Digital compensation of DC drifts can eliminate a need for potentially complex analog feedback circuitry that might otherwise be required. Such feedback circuitry is typically required to cancel DC shifts resulting from thermal fluctuations, component aging, and other long- and short-term drifts.

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DC-Drift Compensation in Digital Signal Processing Systems

       Disclosed is a method to compensate for time-varying
DC-offsets in DC-coupled analog signals.  The method is applicable in
any digital signal-processing system that operates on signals which
are bounded in time.  Digital compensation of DC drifts can eliminate
a need for potentially complex analog feedback circuitry that might
otherwise be required.  Such feedback circuitry is typically required
to cancel DC shifts resulting from thermal fluctuations, component
aging, and other long- and short-term drifts.

      This technique assumes an input signal with intermittent
information content.  Certain transducer-based systems would be an
example.  In such a system, there are time intervals during which the
input signal conveys little information (e.g., a transducer in a
quiescent state). During these intervals of "null" signal, the system
tracks the DC-offset level of the input signal.  When the null signal
is replaced by an information-bearing, "active" signal, the system
processes the incoming data points to extract the information of
interest.  The signal processing that occurs must differentiate
between active and null signals, and must extract the information of
interest from the active signal.

      The flow of control and data is illustrated in the figure.  The
sampled data is filtered as passed to a decision maker to determine
whether or not an active signal is present.  The decision maker uses
filtered data and the output of the baseline tracker to make this
decision. Depending on the shape of a valid active sig...