Applied Underwater Acoustics

11.2. Characterizing the Signal and Noise

11.2.1. Sampling and Quantizing Analog Signals

As noted in Section 11.1.1, signals of interest in underwater acoustics are measured using a transducer converting a physical quantity (e.g., sound pressure) into an analog voltage. Although some high-frequency systems perform limited processing on analog measurements, most signal processing is accomplished using digital processors. Digital processors require the analog measurement to be sampled in time and quantized to a finite set of discrete levels.

Sampling in time first requires analog low-pass filtering the measurement to restrict the spectral content to be below the Nyquist [12] frequency f_s/2, which is half the sampling frequency f_s {unit: Hz}. Any spectral ...