Analog-to-Digital Conversion-A Problem or "Decibels to Digits"

The problem of specifying the capacity of a digitizer, in terms of sampling rate and available bits, is related to the dynamic range of the analog signal to be converted, the noise in the analog system and the use to be made of the digital values. When a transient analog signal is to be converted and subsequently recovered, as required in many geophysical interpretations, a sampling rate as high as eight or ten times per cycle of the highest frequency may be desirable, though costly. On the other hand, a quantizing interval smaller than twice the rms noise provides little additional information in most cases, where the noise frequencies are in the same general range as the signal passband.