Mehtod and apparatus for recovering digital data from baseband analog signal
AssigneeMetricom, Inc.
InventorDavid L. Paulsen
Life of this patent
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Abstract
A data filter consists of an electronic circuit with a delay and offset in a feedback loop to a reference input of a comparator to provide low frequency tracking of a binary-level data signal so digital information can be extracted at the output of the comparator by causing the reference input to track a relatively slowly-varying baseband neutral signal level. The delay is preferably implemented by a low-pass filter, providing additional noise immunity.
Claims13
An apparatus for filtering an input data signal of nominally binary levels for use in extracting binary-valued digital data from said input binary level data signal, said apparatus comprising:
- a comparator having an inverting data input, a non-inverting reference input and a data output, said inverting data input for receiving said input binary level data signal;
- a summer adapted to receive at a first input said input binary level data signal and coupled to receive at a second input a feedback signal, for summing said input binary level data signal and said feedback signal;
- a level offsetting circuit coupled to receive said data output signal for producing said feedback signal, said feedback signal being representative of said data output signal at a level offset which results in a nominal signal excursion about a neutral-valued midpoint;
- and
- a signal delay means coupled to receive output from said summer, said signal delay means being coupled to said non-inverting reference input of said comparator, wherein said reference signal tracks low frequency deviations in said input binary level data signal.
A method for filtering an input data signal of nominally binary levels for use in extracting binary-valued digital data from said input binary level data signal, said method comprising the steps of:
- providing said input binary level data signal to an inverting input of a comparator and to a first summing input of a summer;
- tracking a center reference of said input binary level data signal and generating thereby a reference level signal;
- offsetting level of a feedback signal from output of said comparator for controlling said tracking;
- and
- providing said reference level signal at a non-inverting input of said comparator.
Dependencies are inferred from the claim text.