4B/5B Encoding Simulation

written by Teresa Carrigan

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This model demonstrates the 4B/5B transmission encoding method. 4B/5B is designed to limit the number of consecutive zeroes, and is used by 100Base-FX networks to achieve a 100Mbps data transmission rate.



A random 16-bit pattern is generated. This is the data that we want to transmit on our 100Mbps network. Starting from the left-most bit, each set of 4 bits is replaced by its 5-bit 4B/5B equivalent. The 4B/5B encoding of the data is then transmitted over the network using NRZI transmission encoding. For each bit sent, both a synchronization clock pulse and the transmission waveform are displayed.


Applets on this website were written by Teresa Carrigan in 2004, for use in computer science courses at Blackburn College, with the exception of the Fireworks applet. The applets made with NetLogo require Java 1.4.1 or higher to run. The applets made with NetBeans require Java 1.4.2 or higher to run. Applets might not run on Windows 95 or Mac OS 8 or 9. You may obtain the latest Java plugin from Sun's Java site.