Key telephone system without common control
US6046995A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 26, 1998 |
| Grant date | Apr 4, 2000 |
| Priority date | — |
| Expiry date | May 26, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M9/002
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A multi-line key telephone system not having a key service unit includes three analog telephone lines to which multiple telephone stations may be connected for enhanced communications between stations. Each station is connected by a modem to a single telephone line and includes a Universal Asynchronous Receiver Transmitter (UART) communicating with the modem, a microprocessor and a digital signal processor for effecting voice and data transfers and communicating time division multiplex protocol control to another telephone station on the same line. The UART includes a synchronizer with a master clock for defining positions of voice and data packets within a TDM frame having a predetermined data bit structure, and a receiver for acquiring a first valid packet header and start bit and issuing a sync pulse to adjust the master clock to conform to the timing of a new communication session. A receive data register in the UART temporarily stores data packets indexed to a first position within a TDM frame, and a receive voice buffer accumulates and temporarily stores voice packets indexed to a second position within the TDM frame. Transmitted data and voice packets are initially accumulat…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.