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US 5,636,202 AGranted
Test system for detecting ISDN NT1-U interfaces
AssigneeLucent Technologies Inc.
InventorDavid J. Garney
Life of this patent
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Abstract
The invention is a test method for testing ISDN interfaces from a remote location. The test method of the invention applies predetermined energy signals to the tip and ring leads of the customer subscriber line in a prescribed sequence, delays 10 to 100 ms, and then makes measurements of the voltage across the tip and ring leads. The voltage measurements are compared to limit values identified from the NT1-U dc characteristic curve to determine pass/fail of the tested interface.
Claims19
A method for testing for an ISDN NT1-U interface connected to a telecommunications network by a subscriber line, comprising the steps of:
- a) applying a first energy to the interface over said subscriber line and determining if a first voltage across the interface is within a first predetermined range, said first predetermined range being within a first characteristic range of voltages defining an off state for said interface;
- b) if the first voltage is within the first predetermined range, applying a second energy to the interface over said subscriber line and determining a second voltage across the interface, said second energy being within said first characteristic range;
- c) applying a third energy to the interface over the subscriber line, said third energy being sufficient to turn the interface on;
- d) applying a fourth energy to the interface over said subscriber line, and determining if a third voltage across the interface is within a second predetermined range, said second predetermined range being within a second characteristic range of voltages defining an on state for said interface;
- e) if the voltage is within the second predetermined range, applying a fifth energy to the interface over said subscriber line, said fifth energy being substantially equal to said second energy, and determining a fourth voltage across the interface, said fourth voltage being within said second characteristic range of voltages;
- and
- f) determining the difference between the second voltage and the fourth voltage, and determining if the difference is within a third predetermined range whereby the interface can be identified as an ISDN standard interface.
4 more elements
A method for testing for an ISDN NT1-U interface, comprising the steps of:
- a) applying a first energy to the interface and determining if a first voltage across the interface is within a first predetermined range;
- b) if the first voltage is not within the first predetermined range, reporting a failure condition;
- c) if the first voltage is within the first predetermined range, applying a second energy to the interface and measuring a second voltage across the interface;
- d) applying a third energy sufficient to turn the interface on;
- e) applying a fourth energy to the interface and determining if a third voltage across the interface is within a second predetermined range;
- f) if the third voltage is not within the second predetermined range, reporting a failure condition;
- g) if the third voltage is within the second predetermined range, applying a fifth energy to the interface, and determining a fourth voltage across the interface;
- h) determining the difference between the second voltage and the fourth voltage, and determining if the difference is within a third predetermined range;
- i) removing all energy from the interface and determining if a fifth voltage across the interface is within a fourth predetermined range;
- and
- j) if the fifth voltage is within the fourth predetermined range, reporting a pass condition.
8 more elements
A method for testing for an ISDN NT1-U interface connected to a telecommunications network by a subscriber line, comprising the steps of:
- a) applying a first energy to the interface over said subscriber line and determining a first voltage across the interface, said first energy being within a first characteristic range of voltages defining an off state for the interface;
- b) applying a second energy to the interface over the subscriber line, said second energy being sufficient to turn the interface on;
- c) applying a third energy to the interface over said subscriber line, said third energy being substantially equal to said first energy, and determining a second voltage across the interface, said second voltage being within a second characteristic range of voltages defining an on state for said interface;
- and
- d) determining the difference between the first voltage and the second voltage, and determining if the difference is within a third predetermined range whereby the interface can be identified as an ISDN standard interface.
2 more elements
Dependencies are inferred from the claim text.