Videotelephone apparatus for transmitting high and low resolution video signals over telephone exchange lines
US4888795A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 28, 1988 |
| Grant date | Dec 19, 1989 |
| Priority date | — |
| Expiry date | Jun 28, 2008 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S379/916
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In an audiovisual communication, a first high fram rate video signal is derived from a motion image and converted to a low fram rate low resolution multiframe signal. A second high frame rate video signal is derived from an still image and converted to a single frame high resolution signal. Because of the low frame rates, the frequencies of the low and high resolution signals are within the range of frequencies of a telephone exchange line. A switching matrix is provided to sequentially couple both the low and high resolution signals to a transmission line in response to a mode select signal. The single frame high resolution signal is stored into a memory at the receiving end and repeatedly retrieved out of the memory into a display through the switching matrix.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.