# bit error rate (BER)

The Bit Error Rate (BER) is the ratio of the number of binary

signal elements corrupted during transmission to the total number of binary signal elements sent out. A bit error rate of 1 means that every bit is wrong. An error rate of 6x10exp-6 means that on average 6 bits can be wrong when 1 million bits are transmitted. For different local area networks, the standard prescribes different values for the bit error rate: For Ethernet, the standard requires a BER value of 10exp-8; for Token Ring, 10exp-9; and for FDDI

, 2.5 x 10exp-12. This means that for FDDI, there is one erroneous bit for every 400 billion bits transmitted.

In voice communication, the bit error rate makes itself felt with varying degrees of interference. A bit error rate of 10exp-2 is noticeable as annoying pattering, at 10exp-3 the pattering dissolves into a dense sequence of pops, which at a bit error rate of 10exp-4 changes into individual pops. At 10exp-5, only individual pops are audible and bit error rates of 10exp-6 do not affect voice transmission at all.