Local modulated carrier data network with a collision avoidance protocol
US4608559A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 19, 1982 |
| Grant date | Aug 26, 1986 |
| Priority date | — |
| Expiry date | Aug 19, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L12/2801
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A modem for a single frequency, modulated RF carrier local data network for a distributed data processing system and a method for line acquisition and contention resolution. The protocol established for line acquisition and contention resolution is implemented by a modem controller. The controller causes the receiver section to listen for foreign carriers to determine when the line is busy. When the client device of the modem desires to send a data packet to another unit, the modem controller causes the receiver to listen for a certain pre-burst period and then causes the transmitter to send a burst of RF carrier out on the line and simultaneously causes the receiver to listen to the line for interference beating, i.e. changes in amplitude on the line which indicates another unit is requesting the line. To insure beat patterns, the frequency of the burst carrier is swept over a range during the burst. If a contention is found, a resolution thereof is made utilizing a random delay and retry protocol. After the burst, the controller causes the receiver to listen to the line for other carriers. If none are found, the controller causes the transmitter to transmit a data packet preceded…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.