Integrated data voice multiplexer supporting handshake and loop-back protocols
US4908819A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 23, 1988 |
| Grant date | Mar 13, 1990 |
| Priority date | — |
| Expiry date | Dec 23, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M11/062
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
An integrated data voice multiplexer (IDVM) capable of simultaneously supporting loop-back and communication handshake protocols with no performance degradation. This allows the IDVM to be used in both point-to-point and packet switch networks. The IDVM is of the type using frequency shift keyed FSK modulation of two or more carriers to send a data signal. The presence or absence of carrier signals indicates loop-back state. Narrowband modulation is selectively added to at least one carrier to support handshake protocol. The preferred narrowband modulation is biphase at a rate lower than the FSK modulation rate. Encoder, decoder, data hold and detect circuits for supporting standard RS232 protocol are disclosed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.