Time domain reflectometer for measuring impedance discontinuities on a powered transmission line
US4766386A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 23, 1986 |
| Grant date | Aug 23, 1988 |
| Priority date | — |
| Expiry date | May 23, 2006 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R27/06
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A time domain reflectometer (TDR) for making impedance measurements on a powered transmission line cable system. The TDR is particularly useful for measuring impedance discontinuities on a powered Ethernet system. A negative test pulse is provided to ensure that any positive reflections do not exceed the upper voltage limit of the transceivers. The TDR selectively applies a negative bias to the transmission line cable below the collision detection threshold in order to disable all transceivers and prevent network interference with the TDR measurements. The negative DC bias also provides additional headroom for positive pulse reflections.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.