AT&T Intellectual Property I, LP

At+t Corp.

Wallace F Smith

David Beaumont Ramsden

James Herbert James

Bing Chen

A system and method for recording analog signals exchanged between a telephone device and a VoIP device, capturing packets exchanged between the VoIP device and an IP network, determining analog time values corresponding to analog characteristics of the analog signals, determining digital time values corresponding to digital characteristics of the packets, determining a common reference time for the analog time values and digital time values and determining a processing delay based on the analog time values and the digital time values.

Method for measuring processing delays of voice-over IP devices

The performance of an echo canceller is assessed using a) a test signal launched from originating test equipment and b) a simulated echo of the test signal launched from terminating test equipment. The launch of the simulated echo signal is timed in such a way that it arrives at the tandem echo canceller(s) at a particular point in time relative to the arrival of the test signal, at the tandem echo canceller(s), when the tandem echo canceller(s) is (are) not able to cancel the simulated echo signal. The latter thus arrives uncanceled at the target echo canceller. The launch of the simulated echo signal is further timed in such a way that it arrives at the target echo canceller at a point in time relative to the arrival of the test signal, at the target echo canceller, when the target echo canceller is able to cancel the simulated echo signal. As a result, any residual echo received at the originating test equipment is a measure of the performance of the target echo canceller exclusive of the performance of the tandem echo canceller(s).

Method for testing echo cancellers

A method and apparatus for providing echo cancellation are disclosed. For example, the method receives via an echo canceller a first audio signal directed towards an endpoint device, and adds an inserted signal to the first audio signal directed towards the endpoint device. The method determines if a second audio signal being received from the endpoint device comprises the inserted signal, and cancels at least a portion of the second audio signal that is associated with the first audio signal, if the inserted signal is detected.

Method and apparatus for providing echo cancellation in a network

A system that incorporates teachings of the present disclosure may include, for example, an echo measurement device having a controller to transmit a test signal in a communication path which is looped back at an end point identified as having an echo problem. The test signal can be transmitted at a remote location from the end point. The test signal can be represented by a limited burst signal of one or more frequencies operating outside a range of an operating frequency of an echo canceller deactivation signal transmitted in the communication path. Additional embodiments are disclosed.

Method and apparatus for identifying a fault in a communication path

A method and apparatus enabling the measurement of one way delay in each of the two directions of transmission from a single location are disclosed. The method measures a first roundtrip delay at a first location between a first endpoint and a second endpoint over a first communication network, and measures a second roundtrip delay between a third endpoint and a fourth endpoint over a second communication network with symmetric delay characteristics. The method performs synchronous recordings of a test signal that is sent simultaneously from the second endpoint to the first endpoint and from the fourth endpoint to the third endpoint, to measure an arrival time (t) of the test signal over the first communication network, and, an arrival time (t) of the test signal over the second communication network t, where the arrival times (t) and (t) are used to calculate an one way transmission delay in the first communication network.

Method and apparatus for measuring one way transmission delay

Techniques for measuring a one way delay between two handsets over an Internet protocol (IP) network utilize a delay measurement subsystem connected to both handsets and a procedure to couple a test signal to both handsets and measure the response to the test signal. The delay measurement subsystem is connected to a call originating handset to play an acoustic test signal to the transmitter of the originating handset. The delay measurement subsystem is connected to a call terminating handset to play the acoustic test signal to the transmitter of the call terminating handset and to record acoustic signals received on the call terminating handset. Signals recorded at the call terminating handset include a sidetone signal and a signal received from the call originating handset. The difference between the sidetone signal and the signal received from the call originating handset represents the delay through the handsets and the IP network.

Techniques and apparatus for one way transmission delay measurement for IP phone connections

A method and apparatus for identifying echo sources in a communication path. A system that incorporates teachings of the present disclosure may include, for example, an echo measurement device (EMD) having a transmit module to transmit an echo canceller deactivation signal in a communication path of the communication system, wherein the echo canceller deactivation signal deactivates one or more echo cancellers in said communication path. The transmit module can also transmit a test signal in the communication path which is looped back at an end point identified as having an echo problem, wherein the test signal is transmitted at a remote location from the end point. The EMD can further include a detection module to detect one or more echo signals associated with the test signal. Additional embodiments are disclosed.

Method and apparatus for identifying echo sources in a communication path

A method of measuring echo path delay in a circuit having echo cancellers after enabling an echo signal to pass through the echo cancellers. The known time for a given echo canceller to disable is subtracted from the overall test signal duration. This quantity can be subtracted from the overall echo duration to compute the echo path delay.

Method for remote measurement of echo path delay

A method and system for measuring the signal transmission time through a network link bounded by at least one echo canceller. The method generally includes the steps of determining a signal transmission time (tA) along a network path including the network link bounded by the echo canceller between a first endpoint and a second endpoint, transmitting a test signal from the first endpoint to the second endpoint through the network path, transmitting an echo signal which simulates the test signal from the second endpoint to the first endpoint through the network path, measuring a minimum time delay between transmission of the test signal and transmission of the echo signal which causes the echo canceller to cancel the echo signal and calculating the signal transmission time through the network link bounded by the echo canceller based on the measured minimum time delay and the determined network path signal transmission time (tA). Where the network link is bounded by two echo cancellers, the method further includes the steps of transmitting a second test signal from the second endpoint to the first endpoint through the network path, transmitting a second echo signal which simulates the second test signal from the first endpoint to the second endpoint through the network path, measuring a second minimum time delay between transmission of the second test signal and transmission of the second echo signal which causes the second echo canceller to cancel the second echo signal and calculating the delay through the network link bounded between the first and second echo cancellers based on both measured minimum time delays and the determined network path signal transmission time (tA).

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Sea Girt, NJ, United States of America

Wallace F Smith