Patent Publication Number: US-7899639-B2

Title: Method and apparatus for identifying a fault in a communication path

Description:
PRIOR APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 11/426,226 filed Jun. 23, 2006 by Smith et al., entitled “Method and Apparatus for Identifying Echo Sources in a Communication Path.” All sections of the aforementioned application are incorporated herein by reference. 
    
    
     FIELD OF THE DISCLOSURE 
     The present disclosure relates generally to diagnostic devices, and more specifically to a method and apparatus for identifying a fault in a communication path. 
     BACKGROUND 
     When a subscriber of a communication system reports a voice echo at a service node of said system, a service provider generally deploys a field engineer with test equipment to diagnose the reported problem at its source. It can take some time before the field engineer arrives at the subscriber&#39;s location. Moreover, such testing can be costly to the service provider. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts an exemplary embodiment of a communication system; 
         FIG. 2  depicts an exemplary method operating in an echo measurement device coupled to the communication system; and 
         FIG. 3  depicts an exemplary block diagram illustrating the method of  FIG. 2  for measuring echo sources in a communication path of the communication system; and 
         FIG. 4  depicts an exemplary diagrammatic representation of a machine in the form of a computer system within which a set of instructions, when executed, may cause the machine to perform any one or more of the methodologies disclosed herein. 
     
    
    
     DETAILED DESCRIPTION 
     An embodiment of the present disclosure can entail 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. 
     Another embodiment of the present disclosure can entail a computer-readable storage medium having computer instructions to detect one or more echo signals associated with a test signal transmitted in a communication path and looped back at an end point identified as having an echo problem, the test signal represented by a 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. 
     An embodiment of the present disclosure can entail identifying a fault in a communication path from timing characteristics of one or more echo signal sources from a burst signal transmitted in the communication path, the burst signal operates outside a range of an operating frequency of an echo canceller deactivation signal. 
     Another embodiment of the present disclosure can entail, a loopback apparatus having a loopback circuit applied to an end point of a communication path for identifying a fault in the communication path. The fault can be determined from a test signal transmitted in the communication path and looped back at the loopback circuit. The test signal can be represented by a signal operating outside a range of an operating frequency of an echo canceller deactivation signal. 
       FIG. 1  depicts an exemplary embodiment of a communication system  100 . The communication system  100  comprises a communications network  101  coupled to a building  102  that houses residential or commercial enterprise communication elements, a number of fixed and roaming end users  104  utilizing services of the communications network  101 , and a centralized office  106 . 
     The communications network  101  can utilize packet and/or circuit-switched communications technology such as IP routers and time division multiplexed (TDM) circuit-switched network switches. The communications network  101  can also utilize a combination of wireless and wired interconnections. For example, the communications network  101  can include WiFi access points in residences or commercial enterprises, and WiMax or cellular cell sites dispersed in a wide geographic region. The cellular sites can utilize any number of common frequency-reuse protocols such as GSM, CDMA, UMTS, TDMA, and so on. As a hybrid communication system, the communications network  101  can support Voice over IP (VoIP) and Plain Old Telephone Services (POTS) communications. 
     In a commercial setting, the building  102  can include a PBX (Private Branch Exchange) coupled to a number of terminals  110  supporting VoIP or POTS communications. In a residential setting, VoIP or POTS terminals can be coupled by way of standard wired interfaces to a Service Area Interface (SAI) serving a number of residences by way of a remote central office housing common TDM switching and routing equipment. 
     The centralized office  106  can serve the function of diagnosing issues with the network  101 . The centralized office  106  can be an integral part of a central office housing TDM and IP networking equipment. Thus the centralized office  106  can serve the function of testing and providing communication services to fixed or roaming end users  104 . The fixed end users  104  can receive communication services by way of public phone booths, residences or commercial enterprises, while roaming end users  104  can represent subscribers of WiMax and/or cellular services provided by the network  101 . 
       FIG. 2  depicts an exemplary method  200  operating in an echo measurement device housed by the centralized office  106  (or at any location in the network) for diagnosing echoes in the aforementioned hybrid communications network  101 . Method  200  begins with step  202  in which personnel of the communications network  101  establish by common means a communication path from the centralized office  106  to a trouble point identified by a subscriber of the network  101 .  FIG. 3  depicts an exemplary block diagram of the communication path established in step  202 . 
     An echo measurement device (EMD)  306  of the centralized office  106  can be represented by an Agilent VQT, a GL Communications T1/E1 analyzer, or a proprietary diagnostic system with digital processing capabilities. The location of the EMD  306  is illustrated as a first end point (A) coupled to a second end point (B) by way of the communication path. End point A can be remotely located from end point B by tens or thousands of miles. End point B represents where the trouble was reported. To enable testing, a loopback apparatus  302  is used to loopback signals transmitted by the EMD  306 . The loopback apparatus  302  can include a loopback circuit coupled to a common telephonic interface such as an RJ11 jack. The loopback circuit establishes a signal loop at end point B by interconnecting transmit and receive signals in the communication path (e.g., connecting pins  1  &amp;  3  together, and pins  2  &amp;  4  together). 
     In step  204 , the EMD  306  transmits an echo canceller deactivation signal which deactivates the echo cancellers located in the communication path. The deactivation signal can represent a signal having an operating frequency of 2100 Hz with 180 degree phase reversals occurring every 450 ms. Once the echo cancellers have been deactivated, the EMD  306  proceeds to step  206  where it transmits a test signal in the communication path. The test signal can represent a limited burst signal on the order of for example 25 ms. The burst signal can be short so that multiple echoes, if present, can be detected during the analysis of the communication path. The burst signal can operate on a single or multiple frequencies that are outside a range of the operating frequency of the echo canceller deactivation signal. 
     Once the burst signal is transmitted, the EMD  306  records in step  208  loopback signals. From the recorded signal bursts of energy can indicate whether there are echoes and how many corresponding echo sources may be present. If no echoes are detected in step  209 , the EMD  106  can be programmed to cease operation. Otherwise, the EMD  306  proceeds to step  210  where it calculates a loopback delay (Delay  1 ) for the test signal. As depicted in  FIG. 3  Delay  1  is calculated as a travel time of the test signal to an echo source (t 1 ) plus a travel time of the test signal from the echo source to end point B (t 2 ) plus a travel time from end point B to the echo source (t 3 ) plus a travel time from the echo source to end point A (t 4 ). Hence, Delay  1  is equal to t 1 +t 2 +t 3 +t 4 . 
     In step  212  the EMD  306  calculates a loopback delay (Delay  2 ) for each of the echo sources.  FIG. 3  illustrates this calculation for a single echo source. Delay  2  is equal to a travel time of the test signal to the echo source (t 1 ) plus a travel time of the test signal from the echo source to end point B (t 2 ) plus at travel time from end point B to the echo source (t 3 ) plus a delay for the echo source to loopback the test signal (echo source delay) plus a travel time of the test signal from the echo source to end point B (t 2 ) plus at travel time from end point B to the echo source (t 3 ) plus a travel time from the echo source to end point A (t 4 ). Hence, Delay  2  is equal to t 1 +t 2 +echo source delay+t 2 +t 3 +t 4 . 
     To calculate a roundtrip delay from end point B to the echo source, the EMD  306  in step  214  subtracts Delay  1  from Delay  2 . The echo delay to end point B is t 3 +echo source delay+t 2 . From this delay, the EMD  106  can calculate an approximate location of the echo source in the communication path in step  216 . With this information a field engineer can be called to correct a malfunctioning echo canceller or add an echo canceller in the approximate location it is needed to correct the echo. 
     Although method  200  is demonstrated for a single echo source, a similar procedure can be applied to multiple echo sources. Additionally, the foregoing embodiments of method  200  can save substantial cost incurred by a service provider of the communications system  100 . Operational expenses are reduced by remotely diagnosing echo problems without deploying a field engineer to locations with reported issues. Equally as important, the foregoing method provides a means for rapid testing since all testing can take place at a centralized office  106  or at other locations in the communication system  100 . The EMD  306  can be programmed for example to test a communication path as directed by a customer service agent of the service provider even though the agent may not have familiarity or experience with the testing procedure. If for example the EMD  306  detects an echo confirming the subscriber&#39;s reported problem, the customer service agent can establish a trouble ticket which can then be analyzed by a test engineer that can determine whether field repairs are necessary or an additional echo canceller is required. 
     It would be evident to an artisan with ordinary skill in the art that the aforementioned embodiments of method  200  can be modified, reduced, or enhanced without departing from the scope and spirit of the claims described below. For example the EMD  306  can be programmed to transmit a variety of burst signals to validate the presence of echoes at multiple frequencies rather than at a single frequency. The EMD  306  can be programmed to generate trouble tickets with a suggested remedy for the echoes detected. Additionally, the EMD  306  can be programmed to measure an echo path loss (EPL) from a power measurement of a loopback of the test signal (P 1 ), a power measurement for each of the one or more echo signals (e.g., P 2 ), and an expected power loss at the end point (L) where the communication path is looped back (e.g., EPL=P 2 −P 1 −L). 
     These are but a few examples of modifications that can be applied to the present disclosure. Accordingly, the reader is directed to the claims below for a fuller understanding of the breadth and scope of the present disclosure. 
       FIG. 4  depicts an exemplary diagrammatic representation of a machine in the form of a computer system  400  within which a set of instructions, when executed, may cause the machine to perform any one or more of the methodologies discussed above. In some embodiments, the machine operates as a standalone device. In some embodiments, the machine may be connected (e.g., using a network) to other machines. In a networked deployment, the machine may operate in the capacity of a server or a client user machine in server-client user network environment, or as a peer machine in a peer-to-peer (or distributed) network environment. 
     The machine may comprise a server computer, a client user computer, a personal computer (PC), a tablet PC, a laptop computer, a desktop computer, a control system, a network router, switch or bridge, or any machine capable of executing a set of instructions (sequential or otherwise) that specify actions to be taken by that machine. It will be understood that a device of the present disclosure includes broadly any electronic device that provides voice, video or data communication. Further, while a single machine is illustrated, the term “machine” shall also be taken to include any collection of machines that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein. 
     The computer system  400  may include a processor  402  (e.g., a central processing unit (CPU), a graphics processing unit (GPU, or both), a main memory  404  and a static memory  406 , which communicate with each other via a bus  408 . The computer system  400  may further include a video display unit  410  (e.g., a liquid crystal display (LCD), a flat panel, a solid state display, or a cathode ray tube (CRT)). The computer system  400  may include an input device  412  (e.g., a keyboard), a cursor control device  414  (e.g., a mouse), a disk drive unit  416 , a signal generation device  418  (e.g., a speaker or remote control) and a network interface device  420 . 
     The disk drive unit  416  may include a machine-readable medium  422  on which is stored one or more sets of instructions (e.g., software  424 ) embodying any one or more of the methodologies or functions described herein, including those methods illustrated above. The instructions  424  may also reside, completely or at least partially, within the main memory  404 , the static memory  406 , and/or within the processor  402  during execution thereof by the computer system  400 . The main memory  404  and the processor  402  also may constitute machine-readable media. 
     Dedicated hardware implementations including, but not limited to, application specific integrated circuits, programmable logic arrays and other hardware devices can likewise be constructed to implement the methods described herein. Applications that may include the apparatus and systems of various embodiments broadly include a variety of electronic and computer systems. Some embodiments implement functions in two or more specific interconnected hardware modules or devices with related control and data signals communicated between and through the modules, or as portions of an application-specific integrated circuit. Thus, the example system is applicable to software, firmware, and hardware implementations. 
     In accordance with various embodiments of the present disclosure, the methods described herein are intended for operation as software programs running on a computer processor. Furthermore, software implementations can include, but not limited to, distributed processing or component/object distributed processing, parallel processing, or virtual machine processing can also be constructed to implement the methods described herein. 
     The present disclosure contemplates a machine readable medium containing instructions  424 , or that which receives and executes instructions  424  from a propagated signal so that a device connected to a network environment  426  can send or receive voice, video or data, and to communicate over the network  426  using the instructions  424 . The instructions  424  may further be transmitted or received over a network  426  via the network interface device  420 . 
     While the machine-readable medium  422  is shown in an example embodiment to be a single medium, the term “machine-readable medium” should be taken to include a single medium or multiple media (e.g., a centralized or distributed database, and/or associated caches and servers) that store the one or more sets of instructions. The term “machine-readable medium” shall also be taken to include any medium that is capable of storing, encoding or carrying a set of instructions for execution by the machine and that cause the machine to perform any one or more of the methodologies of the present disclosure. 
     The term “machine-readable medium” shall accordingly be taken to include, but not be limited to: solid-state memories such as a memory card or other package that houses one or more read-only (non-volatile) memories, random access memories, or other re-writable (volatile) memories; magneto-optical or optical medium such as a disk or tape; and carrier wave signals such as a signal embodying computer instructions in a transmission medium; and/or a digital file attachment to e-mail or other self-contained information archive or set of archives is considered a distribution medium equivalent to a tangible storage medium. Accordingly, the disclosure is considered to include any one or more of a machine-readable medium or a distribution medium, as listed herein and including art-recognized equivalents and successor media, in which the software implementations herein are stored. 
     Although the present specification describes components and functions implemented in the embodiments with reference to particular standards and protocols, the disclosure is not limited to such standards and protocols. Each of the standards for Internet and other packet switched network transmission (e.g., TCP/IP, UDP/IP, HTML, HTTP) represent examples of the state of the art. Such standards are periodically superseded by faster or more efficient equivalents having essentially the same functions. Accordingly, replacement standards and protocols having the same functions are considered equivalents. 
     The illustrations of embodiments described herein are intended to provide a general understanding of the structure of various embodiments, and they are not intended to serve as a complete description of all the elements and features of apparatus and systems that might make use of the structures described herein. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. Other embodiments may be utilized and derived therefrom, such that structural and logical substitutions and changes may be made without departing from the scope of this disclosure. Figures are also merely representational and may not be drawn to scale. Certain proportions thereof may be exaggerated, while others may be minimized. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense. 
     Such embodiments of the inventive subject matter may be referred to herein, individually and/or collectively, by the term “invention” merely for convenience and without intending to voluntarily limit the scope of this application to any single invention or inventive concept if more than one is in fact disclosed. Thus, although specific embodiments have been illustrated and described herein, it should be appreciated that any arrangement calculated to achieve the same purpose may be substituted for the specific embodiments shown. This disclosure is intended to cover any and all adaptations or variations of various embodiments. Combinations of the above embodiments, and other embodiments not specifically described herein, will be apparent to those of skill in the art upon reviewing the above description. 
     The Abstract of the Disclosure is provided to comply with 37 C.F.R. §1.72(b), requiring an abstract that will allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separately claimed subject matter.