Method and apparatus having echo cancellation and tone detection for a voice/tone composite signal

A system, comprising:

• an adaptive filter having an input and an output;
• a combiner having a first input, a second input coupled to the output of the adaptive filter, and an output;
• a non-linear processor having an input coupled to the output of the combiner and an output;
• and
• in compliance with a standard called ITU-T Recommendation G.168 for digital network echo cancellers, a send input Sin coupled to the input of the combiner, a send output Sout coupled to the output of the nonlinear processor, and a receive input coupled to the input of the adaptive filter;
• wherein the output of the combiner is user accessible whereby tone detection can be performed on the output of the combiner.

A method of implementing an echo canceller, the echo canceller comprising an adaptive filter, a combiner, and a nonlinear processor;

• the method comprising:
• coupling a first signal to the combiner, wherein the first signal includes echo information, first voice information, and first tone information;
• adaptively filtering a second signal to produce a third signal, wherein the second signal includes second voice information and second tone information;
• providing the third signal to the combiner;
• subtracting, using the combiner, the third signal from the first signal to provide a fourth signal;
• performing tone detection, using the tone detector, on the fourth signal to obtain the second tone;
• and
• performing processing, using the nonlinear processor, on the fourth signal to produce a fifth signal, wherein the processing comprises nonlinear processing.