As we have seen in the preceding chapter, it is common practice to convey the analog conditioned output of a sensor to an analog-to-digital converter, and then pass that sampled data to a digital computer for further processing, storage and display. In this chapter, we introduce some of the basic digital signal processing (DSP) operations done on sampled data, and describe how they are accomplished. They include, but are not limited to, smoothing or low-pass filtering, integration, differentiation, computation of the RMS value of a data sequence, notch, or band reject filterng (to eliminate coherent interference in the signal bandwidth), computation of the discrete Fourier transform of a data sequence to characterize it in the (discrete) frequency domain, and interpolation and extrapolation of data sequences. Some of the DSP algorithms we have just mentioned exist as options in specialized data acquisition software packages and unless an instrumentation engineer is developing a system from scratch, there is often no need to write custom software for a specific, dedicated DSP task. One simply uses a packaged DSP routine on an input sequence to obtain the conditioned output sequence.