Overview

Signal processing is the discipline concerned with analyzing, transforming and interpreting signals — time-varying or spatially varying physical quantities that carry information. Typical examples include audio and speech, images and video, radar returns, and biological traces such as electrocardiograms. Practical tasks range from cleaning and compressing measurements to extracting features used by higher-level systems or humans. For a general introduction see introductory resources.

Core concepts

At its foundation signal processing distinguishes between the time (or space) domain and the frequency domain. Tools such as the Fourier transform reveal spectral content while filtering and convolution modify how components combine. Important ideas include sampling and reconstruction (the sampling theorem), quantization, noise reduction, and parameter estimation. For examples of domains and media, consult linked materials on audio and speech and image processing.

Common techniques and tools

  • Transforms: Fourier, short-time Fourier, Laplace and wavelet transforms for analysis and compression.
  • Filtering: FIR and IIR filters, adaptive filters, and spectral shaping to separate signals from interference.
  • Sampling and reconstruction: strategies to digitize analog signals while preserving information.
  • Estimation and detection: statistical methods for identifying patterns, e.g., radar target identification or biomedical event detection.

Applied toolkits and standards often appear in textbooks and online guides; see further reading at radar and remote sensing and data storage and reconstruction.

Applications and examples

Signal processing underpins many everyday systems: noise reduction and equalization in audio, compression algorithms for images and video, channel coding and modulation in communications, and feature extraction in medical monitoring. Examples include aircraft identification by radar, image compression used for photography and web imagery, and ECG analysis in clinical settings. Practical demonstrations and case studies are available via noise and separation techniques and compression examples.

History and distinctions

The field grew from electrical engineering and applied mathematics as analog circuits gave way to digital implementations in the mid-20th century. Modern signal processing overlaps with statistics, machine learning and control theory but remains distinct in its emphasis on transforms, filtering, and real-time implementation. Key distinctions include analog versus digital processing, continuous versus discrete signals, and deterministic versus stochastic models.

Understanding signal processing provides tools to design, evaluate and improve systems that sense, communicate and interpret real-world phenomena. Further reading in textbooks and online courses can guide deeper study of specific methods and applications.