Errored second

In data communication, an errored second is an interval of a second during which any bit error whatsoever has occurred, regardless of whether that error was a single bit error, or a complete loss of communication for that entire second, is not important for the purpose of counting errored seconds.

In communication systems with very low uncorrected bit error rates, such as modern fiber optic systems, errored seconds are often a better measure of effective error rate than simple bit error rate. For many modern communication systems, even a single uncorrected bit error is enough to cause the loss of a data packet by causing its CRC to fail; whether that packet loss was caused by a single bit error or a burst of a hundred-bit-long error burst is irrelevant.