Decision directed DC offset removal
First Claim
1. A method comprising:
- associating each of a plurality of expected values with a value range;
determining that a corrected signal falls within the value range of a particular expected value of the plurality of expected values;
deriving an error value by subtracting the particular expected value from the corrected signal; and
adding the error value to an accumulated error value;
limiting the accumulated error value to a particular range that is based on a minimum distance between the plurality of expected values;
wherein the corrected signal is derived by subtracting the accumulated error value from a received signal; and
wherein the received signal is derived from a radio signal.
6 Assignments
0 Petitions
Accused Products
Abstract
A method and apparatus for decoding a baseband signal of a radio signal removes, from the baseband signal, low-frequency and long-term noise that increases the possibility of decoding errors. The removal of low-frequency and long-term noise is performed by accumulating differences between the actual signal levels of the baseband signal and the expected signal levels for the baseband signal and subtracting the accumulated difference from the baseband signal before decoding. In one scheme, the baseband signal contains a predetermined training sequence of signal levels, where the differences between the actual signal levels of the baseband signal and the expected signal levels for the predetermined training sequence are accumulated. At the end of the training sequence, the accumulated training sequence difference is used as the accumulated difference and subtracted from the baseband signal, thereby providing stable operation for decoding signal levels that follow the training sequence.
17 Citations
18 Claims
-
1. A method comprising:
-
associating each of a plurality of expected values with a value range; determining that a corrected signal falls within the value range of a particular expected value of the plurality of expected values; deriving an error value by subtracting the particular expected value from the corrected signal; and adding the error value to an accumulated error value; limiting the accumulated error value to a particular range that is based on a minimum distance between the plurality of expected values; wherein the corrected signal is derived by subtracting the accumulated error value from a received signal; and wherein the received signal is derived from a radio signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 15, 16)
-
-
8. An apparatus comprising:
-
a comparator that; associates each of a plurality of expected values with a value range; and determines that a corrected signal falls within the value range of a particular expected value of the plurality of expected values; a first subtractor that subtracts the particular expected value from the corrected signal to derive an error value; an accumulator that adds the error value to an accumulated error value; a limiter which limits the accumulated error value to a particular range that is based on a minimum distance between the plurality of expected values; and a second subtractor that subtracts the accumulated error value from a received signal to derive the corrected signal; wherein the received signal is derived from a radio signal. - View Dependent Claims (9, 10, 11, 12, 13, 14, 17, 18)
-
Specification