Half-duplex or full-duplex automode operation for use in data communications equipment
US5349635A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 19, 1992 |
| Grant date | Sep 20, 1994 |
| Priority date | — |
| Expiry date | Nov 19, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L5/14
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A V.32 compatible modem provides a full-duplex mode of operation, while a 208B compatible modem provides a half-duplex mode of operation. The connect sequence of a V.32 compatible modem is modified so that it will automatically determine if the other modem, whether the originating modem or the answering modem, is a 208B type of modem or a V.32 type of modem. In one embodiment of the invention, the connect sequence of an originating V.32 modem is modified to detect either a 2100 Hz answer tone, which represents that the answering modem is a V.32 type of modem, or a 2021 Hz answer tone, which represents that the answering modem is a 208B type of modem. In another embodiment of the invention, the connect sequence of an answering V.32 modem is modified to transmit first a 2100 Hz answer tone and then, if no 1800 Hz V.32 signal "AA" is received from the originating modem, to transmit a 2021 Hz answer tone, thereby simulating a 208B modem has answered the data call. In either case, once the identity of the other modem is determined, this modified modem will then switch to either a half-duplex mode or a full-duplex mode of operation as appropriate.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.