Qualifying telephone line for digital transmission service
US5978449A · kind A · utility
23Cited by
10References
32Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Dec 21, 1998 |
| Grant date | Nov 2, 1999 |
| Priority date | — |
| Expiry date | Dec 21, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M3/305
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A telephone wire pair is qualified for digital signal transmission by central office testing. The tip-to-ring capacitance of the wire pair is measured while applying to the wire pair an AC test signal at 600 Hz. The test signal at this frequency minimizes errors due to line inductance and/or a ringing device connected to the wire pair. Reliable measurement of the length of the wire pair is achieved. Flaws in cable sheathing can also be detected based on measurement of tip-to-ground capacitance and/or ring-to-ground capacitance.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.