Detecting a DC nonlinearity terminating a network
US4501935A · kind A · utility
1Cited by
3References
8Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Jul 20, 1983 |
| Grant date | Feb 26, 1985 |
| Priority date | — |
| Expiry date | Jul 20, 2003 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M3/14
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A methodology for identifying a telephone receiver-off-hook (ROH) condition within the class of resistive faults occurring on a subscriber line is disclosed. The method utilizes the nonlinear DC characteristic exhibited by an off-hook handset. First and second DC resistances are measured in response to first and second DC sources applied at a test point associated with the line. A resistance differential between the two resistances is compared to a resistance range. A ROH condition is indicated if the differential falls within the range.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.