Disabling of echo cancelers after call startup

• US 6,212,374 B1
• Filed: 01/27/1998
• Issued: 04/03/2001
• Est. Priority Date: 06/23/1997
• Status: Expired due to Term

• Current Assignee: Intellectual Properties I KFT
• Original Assignee: Paradyne Corporation (Dasan Networks Incorporated)
• Inventors: Scott, Robert E., Lastinger, Jr., E. Robert
• Primary Examiner(s): LE, THANH C
• Application Number:
  US09/013,573
• Time in Patent Office: 1,162 Days
• Field of Search: 455/422, 455/450, 455/507, 455/517, 455/550, 455/570, 455/575, 455/436, 379/389, 379/406, 379/409, 379/410
• US Class Current: 455/422.1
• CPC Class Codes: H04B 3/23 using a replica of transmitted signal in the time domain, e.g. echo cancellers

Abstract

An echo canceler disabling system is associated with a cellular data communications device, such as a modem, which is utilized to communicate digital data over a cellular network for the purpose of enhancing digital data communications over the network. The echo canceler disabling system is configured to disable voice echo cancelers brought on-line during digital data transmission after call startup in order to prevent disruption of digital data communications by the voice echo cancelers. To deactivate the voice echo cancelers, the echo canceler disabling system is configured to transmit a tone at approximately 2100 Hz with 180 degree phase reversals to disable one or more echo cancelers brought on-line after the call startup. In architecture, the echo canceler disabling system includes a mechanism to detect a loss of signal synchronization, a mechanism to send an echo canceler disable tone, and a mechanism to send a retrain signal after the echo canceler disable tone is sent in order to reestablish signal synchronization.

Claims

1. A system comprising:

means for generating a voice echo canceler disable tone; and

means for transmitting said echo canceler disable tone, wherein said transmitted voice echo canceler disable tone disables voice echo cancelers in a cellular network brought on-line after call startup due to a hand off of communication from a first communication channel to a second communication channel.

2. The system of claim 1 further comprising:

circuitry to detect a loss of signal synchronization.

3. The system of claim 2, wherein said circuitry to detect a loss of signal synchronization further comprises a digital signal processor.

4. The system of claim 2, wherein said tone generator is responsive to circuitry that detects said loss of signal synchronization.

5. The system of claim 2, wherein said retrain signal is stored on memory within said modem.

6. The system of claim 2, wherein said echo canceler disable tone has a frequency corresponding to approximately 2100 Hertz.

7. The system of claim 4, wherein said means for generating a voice echo canceler disable tone further includes a tone generator, and wherein said transmitting means is configured to transmit a retrain signal to reestablish the system synchronization.

8. The system of claim 7, wherein said retrain signal is transmitted with said voice echo canceler disable tone.

9. The system of claim 7, wherein said retrain signal is transmitted after said voice echo canceler disable tone.

10. A system for disabling an echo canceler that is brought on-line after an initiation of a call, comprising:

means for detecting a loss of signal synchronization;

means for sending an echo canceler disable tone; and

means for sending a retrain signal with or after said echo canceler disable tone to reestablish signal synchronization.

11. The system of claim 10, wherein the loss of signal synchronization occurs due to a handoff of a transmission signal in a cellular network.

12. A system for disabling an echo canceler that is brought on-line after an initiation of a call, comprising:

modem circuitry capable of data transmission via a cellular network, said data transmission being accomplished by establishing signal synchronization with a second modem;

circuitry to communicate the occurrence of a handoff to said modem circuitry, said handoff causing an introduction of an echo canceler on-line which causes a loss of signal synchronization; and

a retrain sequence with an echo canceler disable tone, said retrain sequence being sent after the handoff to disable the echo canceler brought on-line in the cellular network after the handoff, thereby reestablishing signal synchronization.

13. A method for disabling an echo canceler activated on-line in a cellular network after call startup during digital data transmission, comprising the steps of:

detecting a loss of signal synchronization in a modem;

sending a retrain sequence to reestablish signal synchronization; and

sending an echo canceler disabling tone with said retrain sequence to disable new echo cancelers brought on-line.

14. The method of claim 13, further comprising the step of storing said retrain signal with said echo canceler disabling tone in memory within said modem.

15. The method of claim 13, wherein the echo canceler disabling tone has a frequency of approximately 2100 Hertz.