Transceiver for multi-drop local area networks
US4597082A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 6, 1984 |
| Grant date | Jun 24, 1986 |
| Priority date | — |
| Expiry date | Mar 6, 2004 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B2203/5495
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A multi-drop local area network utilizes alternating current power lines as a transmission channel. Identical transceivers are used as a master and as up to 255 slaves. Each transceiver comprises modulator and demodulator units and a microprocessor control unit which may be connected to a host. The modulator and demodulator are connected to the alternating current power line through a high pass filter comprising a split bobbin, iron core transformer having an air gap which also provides impedance matching. The demodulator includes a clipper and analog circuitry providing a band pass filter and generating a square wave corresponding to the received carrier. A state machine acting as a digital filter produces a received carrier signal only when each half cycle of the carrier square wave is of the proper duration and the carrier signal has existed for slightly more than one half of the transmitted bit duration, which is a predetermined number of carrier cycles. The microprocessors are programmed to provide for block ahead acknowledgment, alternate transmissions between master and slaves; each block message comprises an acknowledgment non-acknowledgment bit, a message sequence bit, a p…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.