06345100 is referenced by 137 patents.

Watermark data is encoded in a digitized signal by forming a noise threshold spectrum which represents a maximum amount of imperceptible noise, spread-spectrum chipping the noise threshold spectrum with a relatively endless stream of pseudo-random bits to form a basis signal, dividing the basis signal into segments, and filtering the segments to smooth segment boundaries. The data encoded in the watermark signal is precoded to make the watermark data inversion robust and is convolutional encoded to further increase the likelihood that the watermark data will subsequently be retrievable notwithstanding lossy processing of the watermarked signal.

Title
Robust watermark method and apparatus for digital signals
Application Number
9/172935
Publication Number
6345100 (B1)
Application Date
October 14, 1998
Publication Date
February 5, 2002
Inventor
Earl Levine
Palo Alto
CA, US
Agent
James D Ivey
US
Assignee
Liquid Audio
CA, US
IPC
H04K 1/02
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