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Voice Feature Guide 01

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Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
POTS User Loop Line Test

POTS User Loop Line Test

A POTS user loop line test is used to test the electrical indicators of the line from the test device (an access node) to a phone. When users' POTS services are faulty, POTS user loop line tests can be performed to test the performance and electrical indicators of the loop line to diagnose whether the loop line is faulty.

NOTE:

The to-be-tested POTS port must not be faulty.

Networking Application

Figure 1-141 shows the example network of a POTS user loop line test. A POTS user loop line test is used to locate faults on the line from an access node to a phone.
Figure 1-141 Example network of a POTS user loop line test

Test Procedure

Figure 1-142 shows the test procedure of a POTS user loop line test.
Figure 1-142 Test procedure of a POTS user loop line test
  1. (Optional) Maintenance engineers set the parameters for the access node on the NMS or remotely log in to the access node from a management PC to set the parameters.
    NOTE:
    Generally, the default parameter values are used, and maintenance engineers do not need to set them.
    • In test mode, run the pots test-para command to set the physical layer parameters.

      During a loop line test, to avoid affecting the services and functions of the live network, it is necessary to set the physical layer parameters to control the electrical indicators, such as the maximum and minimum voltages supported by the test.

    • In test mode, run the pots loop-line-threshold command to set thresholds of the test.

      The access node uses these thresholds as the criteria to check whether the line is faulty when analyzing the test data.

  2. Maintenance engineers start a loop line test by using the NMS or running the pots loop-line-test command.
    If users (connected to the access node) are making calls during a loop line test, maintenance engineers can cancel, forcibly perform, or delay the test based on actual conditions.
    NOTE:
    If maintenance engineers forcibly perform the test, services on the port are interrupted and users' telephone services are affected. Therefore, exercise caution when performing this operation.
  3. The access node collects the data of the test items. Table 1-19 lists the loop line test items.
    Table 1-19 Loop line test items

    Test Item

    Specific Test Item

    Voltage

    A->G DC voltage

    B->G DC voltage

    A->B DC voltage

    A->G AC voltage

    B->G AC voltage

    A->B AC voltage

    A->G AC frequency

    B->G AC frequency

    A->B AC frequency

    Resistance

    A->ground insulation resistance

    B->ground insulation resistance

    A->B insulation resistance (low)

    B->A insulation resistance (low)

    A->B insulation resistance (high)

    B->A insulation resistance (high)

    Capacitance

    A->ground capacitance

    B->ground capacitance

    A->B capacitance (low)

    A->B capacitance (high)

    Conductance

    A->ground conductance

    B->ground conductance

    A->B conductance (low)

    A->B conductance (high)

    Susceptance

    A->ground susceptance

    B->ground susceptance

    A->B susceptance (low)

    A->B susceptance (high)

    Current

    A->ground DC current

    B->ground DC current

    A->B DC current

    B->A DC current

    A->ground AC current

    B->ground AC current

    A->B AC current

    B->A AC current

  4. The access node analyzes the collected data according to the algorithm, and outputs the test conclusion.
  5. The access node reports the test conclusion, and maintenance engineers diagnose whether the tested line is faulty based on the test conclusion.

Test Conclusion

Table 1-20lists the loop line test conclusions.
Table 1-20 OLT loop line test conclusions

Item

Conclusion

Line state

Normal

A->ground AC voltage is hazardous to persons

B->ground AC voltage is hazardous to persons

AB->ground AC voltage is hazardous to persons

A->ground EMF AC voltage exist

B->ground EMF AC voltage exist

AB->ground EMF AC voltage exist

A->ground abnormal AC voltage exist

B->ground abnormal AC voltage exist

AB->ground abnormal AC voltage exist

A->ground DC voltage is hazardous to persons

B->ground DC voltage is hazardous to persons

AB->ground DC voltage is hazardous to persons

AC voltage between A line and B line is hazardous to persons

DC voltage between A line and B line is hazardous to persons

A->ground EMF DC voltage exist

B->ground EMF DC voltage exist

AB->ground EMF DC voltage exist

A->ground abnormal DC voltage exist

B->ground abnormal DC voltage exist

AB->ground abnormal DC voltage exist

A line grounding

B line grounding

AB line grounding

A->ground resistance fault

B->ground resistance fault

AB->ground resistance fault

A->ground resistance leak

B->ground resistance leak

AB->ground resistance leak

AB->ground poor insulation

AB->ground capacitance leak

A->ground capacitance leak

B->ground capacitance leak

Double line break or no terminal

A line break

B line break

Cut off in MDF (that is, a line cut occurs between the main distribution frame and the device)

Cut off out MDF (that is, a line cut occurs between the main distribution frame and the user side)

Unknown

PPA test result
NOTE:
A passive test termination (PPA) is similar to a test reference point. It is used to detect whether a fault occurs on the loop line between a point and the PPA so that maintenance engineers can locate faults section by section.

PPA not detected

A->B PPA detected

B->A PPA detected

A->B 2 PPA detected

B->A 2 PPA detected

Terminal status

Off hook

ETSI Signature or Elec ring circuit

A-B short

R-C network (on hook or modem exist)

Other terminal

Self mixed in MDF (shorted wires within the same twisted pair, occurring between the main distribution frame and the device)

Self mixed out MDF (shorted wires within the same twisted pair, occurring between the main distribution frame and the user side)

References

Reference standard and protocol: ITU-T G.996.2 Single-ended line testing for digital subscriber lines (DSL)

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Updated: 2019-02-22

Document ID: EDOC1100067358

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