Half-duplex echo canceler training using a pilot signal

• US 5,828,657 A
• Filed: 09/29/1995
• Issued: 10/27/1998
• Est. Priority Date: 09/29/1995
• Status: Expired due to Term

• Current Assignee: Brandywine Communications Technologies LLC (Acacia Research Corporation)
• Original Assignee: Paradyne Corporation (Dasan Networks Incorporated)
• Inventors: Betts, William Lewis, Hazen, Ramon B., Scott, Robert Earl
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): HOM, SHICK C
• Application Number:
  US08/536,916
• Time in Patent Office: 1,124 Days
• Field of Search: 370/286, 370/289, 370/290, 370/291, 370/292, 370/296, 370/269, 375/296, 375/222, 375/340, 375/348, 375/349, 375/350, 379/388, 379/410, 379/411, 455/43
• US Class Current: 370/289
• CPC Class Codes: H04B 3/238 using initial training sequence

Abstract

A far-end modem transmits a "pilot tone" during the time that a near-end modem is training its echo canceler. Correspondingly, the near-end modem is modified to notch, or filter, out this pilot tone from the received signal. The filtered received signal is then used by the near-end modem to train its echo canceler.

Claims

1. Data communications equipment apparatus comprising:

an echo canceler that is trained during an echo-canceler training phase of a half duplex training sequence with a far-end data communications equipment while the communication channel is operating in a linear mode; and

a filter that filters a received signal during the echo-canceler training phase to remove a pilot signal transmitted by the far-end data communications equipment before application of the received signal to the echo canceler to train the echo canceler on an echo signal component thereof.

2. The apparatus of claim 1 comprising transmitter circuitry that transmits a training signal during the half-duplex training phase to act as a source for the echo signal.

3. A method for training an echo canceler during a training sequence of a data connection, the method comprising the steps of:

transmitting a training signal to far-end data communications equipment;

receiving, during a half-duplex training sequence, a signal that comprises an echo signal of the training signal and a pilot signal transmitted by the far-end communications equipment;

filtering the received signal to remove the pilot signal to provide a filtered signal; and

training the echo canceler on the filtered signal while the communications channel is operating in a linear mode.

4. The method of claim 3 wherein the pilot signal is a tone.

5. A method for training an echo canceler during a training sequence of a data connection, the method comprising the steps of:

performing a half-duplex training sequence with an opposite data communications equipment that includes the step of transmitting a pilot signal during that portion of said half-duplex training sequence in which the opposite data communications equipment trains its echo canceler while the communication channel is operating in a linear mode; and

communicating data in a data phase of the data connection subsequent to said half-duplex training sequence.

6. The method of claim 5 wherein the pilot signal is a tone.