On noise in digital recording

A set of rules, equations and relations are given for the effects of coherent and statistical noise on digital recorders. Simple formulas, intended for laboratory use, are given for the change in signal to noise ratio (SNR) caused by the channel. Bit error probability is related to SNR and channel parameters for the zero-crossing detector channels typical of digital computer disk and tape recorders, and many digital instrumentation recorders. Valid and invalid ways to calculate error rate statistics are discussed for situations where bit errors are correlated, i.e. not statistically independent.