Method and system for dynamic aliasing suppression

A method for aliasing suppression in a sub-bands audio system, the method comprising the steps of:

• a. providing near-end analog audio input interface;
• b. providing a far-end;
• c. transmitting near-end audio signal from said near-end to said far-end and receiving far-end audio from said far-end by said near-end;
• d. applying a dynamic anti aliasing suppression (DAAS) with varying aggressiveness on the near-end audio signal, for suppressing an existing non linear aliasing component, wherein said varying aggressiveness is responsive to the activity of said far-end and the activity of said near-end, and wherein said varying aggressiveness is defined at a predefined maximal level when only far-end is active, approximately zero when far-end is inactive and at a predefined intermediate levels of aggressiveness when both far-end and near-end are simultaneously active.

A speaker phone system that performs dynamic anti aliasing suppression on sub-bands digital audio signals, the system comprises:

• a. N≧2 sub-bands decoders that decode encoded digital audio data that is transmitted by a far-end audio source;
• b. a combining device for receiving and merging decoded audio data that is transmitted by said N≧2 sub-band decoders;
• c. a digital to analog converter that transforms the output from said combining device into an analog audio signal and provides the analog audio signal to analog audio output interface;
• d. a near-end analog audio input interface that provides analog audio signal that is converted into digital audio signal by A2D unit and split into N≧2 sub-bands of digital audio signal;
• e. N dynamic anti aliasing suppressors (DAAS) where each of said N≧2 DAAS suppresses one of said N sub-bands of digital audio signal applying a varying level of aggressiveness to suppress an existing non linear aliasing component, wherein said varying aggressiveness is defined at a predefined maximal level when only far-end is active, approximately zero when far-end is inactive and at a predefined intermediate levels of aggressiveness when both far-end and near-end are simultaneously active;
• f. N subtraction units, each subtraction unit receives a suppressed sub-bands of digital audio data after being suppressed by said DASS and subtract an echo cancelling signal that is provided by an echo cancelling unit;
• and
• g. N encoders, where each of the encoders receives and encodes the output of one subtracting unit.