System and method for cancelling echo in a communications line

1. An echo canceller system, comprising:

a first echo canceller having a first voltage divider and an adaptable second voltage divider that is configured to generate a first replica of an echo;

a second echo canceller that is configured to generate a second replica of an echo, the second echo canceller having tap values that are generated in response to an error signal; and

a controller coupled to the first and second echo cancellers, wherein said controller includes a selection algorithm selects a voltage divider value for the adaptable second voltage divider based on the tap values of the second echo canceller.

2. The echo canceller system according to claim 1 , wherein said first echo canceller comprises a first amplifier that receives a downstream analog signal and a second amplifier that receives a portion of an output from the first amplifier and a portion of a return echo signal from remote equipment.

3. The echo canceller system according to claim 2 , wherein said controller is configured to select a balance impedance that reduces an amount of echo upstream through the second amplifier.

4. The echo canceller system according to claim 1 , wherein said second echo canceller comprises a digital echo canceller.

5. The echo canceller system according to claim 1 , wherein said first echo canceller comprises an analog echo canceller.

6. The echo canceller system according to claim 1 , wherein said selection algorithm is based on a cancellation relation among transfer functions.

7. An echo canceller system comprising:

a first echo canceller having a first voltage divider and an adaptable second voltage divider that is configured to generate a first replica of an echo;

a second echo canceller that is configured to generate a second replica of an echo, the second echo canceller having tap values that are generated in response to an error signal; and

a controller coupled to the first and second echo cancellers, wherein

said controller includes a selection algorithm selects a voltage divider value for the adaptable second voltage; and

said selection algorithm is based on a cancellation relation of H1-H2 N -H3, and H1 represents a transfer function of the first voltage divider, H2 N represents a transfer function of an Nth second voltage divider and H3 represents a transfer function of the second echo canceller as a digital echo canceller after the taps have converged.

8. A method of cancelling an echo, which comprises:

capturing digital echo canceller tap values of a digital echo canceller; and

selecting a voltage divider value for an analog echo canceller based on the tap values of the digital echo canceller.

9. The method according to claim 8 , which further comprises receiving a downstream analog signal at a first amplifier and receiving a portion of an output from the first amplifier and a portion of a return echo signal from remote equipment at a second amplifier.

10. The method according to claim 9 , which further comprises selecting a balance impedance that reduces an amount of echo upstream through the second amplifier.

11. The method according to claim 8 , which further comprises selecting a cancellation relation among transfer functions for adjusting a new second voltage divider value.

12. A method of cancelling an echo, comprising:

establishing a telephone connection in a communications line that includes an analog echo canceller having a first voltage divider and a second voltage divider;

capturing digital echo canceller tap values;

selecting a new second voltage divider value based on the tap values of the digital echo canceller; and

selecting a cancellation relation among transfer functions for adjusting a new second voltage divider value, wherein said cancellation relation comprises H1-H2 N -H3, and H1 represents the transfer function of the first voltage divider, H2 N represents the transfer function of an nth second voltage divider and H3 represents the transfer function of a second echo canceller as a digital echo canceller after the taps have converged.

13. A device comprising:

a controller input that is configured to connect to a digital echo canceller and receive tap values of the digital echo canceller;

a controller output that is configured to connect to an adaptive echo canceller; and

logic configured to select a voltage divider value for the adaptive echo canceller based on the tap values received through the controller input and output the selected voltage divider output on the controller output.