CDMA subtractive demodulation

A system for decoding a composite signal having overlapping, coded signals, comprising:

• means for iteratively performing orthogonal transformations on said composite signal with a series of codeword and generating for each transformation a plurality of transformation components, each transformation component being associated with a codeword and an index;
• means for iteratively extracting the coded signal corresponding to a greatest component from said composite signal;
• means for periodically performing at least one orthogonal transformation on a remaining portion of said composite signal with said codewords;
• and
• means for eliminating any transformation component corresponding to said associated index of at least one previous codeword.

A method for decoding a composite signal having overlapping, coded signals, comprising:

• (a) iteratively performing orthogonal transformations on said composite signal with a plurality of codeword and generating for each transformation a plurality of transformation components, each transformation component having an associated codeword and index;
• (b) iteratively extracting a coded signal corresponding to a greatest transformation component from said composite signal;
• (c) periodically performing at least one orthogonal transformation on a remaining portion of said composite signal using said codewords;
• and
• (d) eliminating any transformation component corresponding to said associated index of at least one previously extracted coded signal.

A method for decoding a composite signal having overlapped, coded signals and time-delayed echoes of at least some of said coded signals, comprising:

• (a) correlating a series of codewords with a plurality of time-shifted versions of said composite signal and generating a set of correlations for each time-shifted composite signal;
• (b) combining all of said sets of correlations for said time-shifted composite signals to produce a combined set of correlations;
• (c) determining a codeword corresponding to a greatest correlation in said combined set;
• and
• (d) subtracting said determined codeword from at least one of said time-shifted composite signals.