This chapter examines the basic constructs of signal input, processing using digital filters, and output and focuses on fundamental techniques for extracting information from the signals. Bandpass sampling systems are extremely useful to adaptive signal processing systems which use high-frequency sensor data but with a very narrow bandwidth of interest. The design of analog circuits with nearly zero offset voltage is a difficult enough task that one should always assume some nonzero offset in all digitized sensor data. Adaptive signal processing systems can, and should, adaptively adjust input and output gains while maintaining floating-point data calibration. The integer samples from the analog-to-digital converter (ADC) are further converted to floating-point format by the signal processor chip before subsequent processing. Floating-point digital signal processors subsequently convert the integers from the ADC to their internal floating-point format for processing, and then back to the appropriate integer format for digital-to-analog converter conversion.