Line interface circuit
US5179586A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 13, 1991 |
| Grant date | Jan 12, 1993 |
| Priority date | — |
| Expiry date | Mar 13, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L9/40
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
An interface unit for interconnecting a telephone central switch to a personal computer. The interface unit receives power and data from the switch over a two wire twisted pair. The data is in a half duplex T.C.M. format and is transformed into standard digital data with the logic "1" and "0" being represented by +5V and 0V respectively. The standard digital data is then arranged into 8 bit words and encoded in either an asynchronous or synchronous manner depending on the type of computer. The interface unit has a line interface circuit which provides the physical interface between the interface unit and the computer. The interface unit has a transmitter circuit which converts the +5V and 0V digital signals to -5V and +5V, respectively. These values are recognized by the computer as logic "1" and "0". The interface unit also has a receive circuit which takes the computer output signals (between -5 and -12V for logic "1" and between +5 and +12V for logic "0") and converts them back into standard digital format.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.