Image communication system, and image communication apparatus and modem used in the system
US5351134A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 21, 1992 |
| Grant date | Sep 27, 1994 |
| Priority date | — |
| Expiry date | Dec 21, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N2201/33371
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In an image communication system capable of performing communication at a plurality of transmission speeds, a transmission-side apparatus transmits a line condition check signal (a TCF signal of the CCITT facsimile recommendation T30, or the like) for determining a transmission speed prior to communication of image data. A reception-side apparatus determines an optimal transmission speed on the basis of a reception state of the line condition check signal (a square error accumulation value, an error count result, or the like in an equalizer of a reception-side modem), and informs the determined transmission speed or a fall-up or fall-down instruction of a transmission speed to a necessary step to the transmission-side apparatus. The optimal transmission speed according to a line condition can be set within a very short period of time.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.