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 is not important.

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.