Patent ID: 6765971
Filing Date: 2004-07-20
Classification: H04B,H04L,H04M

Abstract:
A digital signal detection method, comprising:(a) partitioning a digital signal into a plurality of frames; (b) calculating a number of zero crossings of the digital signal within each frame; (c) determining whether or not an absolute value of a difference of the number of zero crossings in between frames is less than a first predetermined value; (d) determining whether or not a sum of the zero crossings of the frames is greater than or equal to a second predetermined value and less than or equal to a third predetermined value; (e) calculating a maximum amplitude of the digital signal for each of the frames; (f) calculating an average amplitude of the digital signal from all of the frames; (g) determining whether or not an absolute value of a difference between said maximum amplitude for each of the frames and said average amplitude from all of the frames is less than a fourth predetermined value times said average amplitude from all of the frames; and (h) determining that the plurality of frames contain a narrowband digital signal if the determining steps (c), (d), and (g) are met.