Multipoint data communication system with collision detection
Communications network repeater
Port logic for a communication bus system
Optically coupled serial communication bus
Demand driven access mechanism
Apparatus and method for collision avoidance
Threshold-less collision detection and bit arbitration in a CFSK data system Patent #: 4409593
ApplicationNo. 06/499796 filed on 05/31/1983
US Classes:370/480, Combining or distributing information via frequency channels370/489, Bus (distributed stations)455/527Break-in or priority override
ExaminersPrimary: Olms, Douglas W.
Assistant: Greer, Timothy K.
Attorney, Agent or Firm
International ClassH04L 12/28 (20060101)
AbstractA transceiver provides data collision detection and avoidance in a contention-formatted, FDM communications network using FSK modulation. Locally-generated baseband data is compared to recovered baseband data received from the system bus. A failure to compare indicates that there has been a data collision. The wide disparities in amplitude between locally-generated FDM signals and signals received from the bus are accommodated by a signal splitter which provides greater attenuation of the local signal than the generally weaker bus signal, and by the use of logarithmic amplifiers which generate relatively constant output levels for a wide range of input signal amplitudes. Collision avoidance is provided by monitoring the bus signal demodulators for data activity, and by inhibiting the local transmitter when such activity is detected, subject to an override during transmission by the local station.