Heterodyne is a technique used in signal processing that involves mixing two different frequencies to produce new frequencies. This process typically generates a sum and a difference frequency, allowing for the extraction of information from a signal. Heterodyne methods are commonly used in radio communications and radar systems to improve signal clarity and range. In a heterodyne system, a local oscillator generates a stable frequency that is combined with the incoming signal. The resulting difference frequency can be easier to analyze and process, making it a valuable tool in technologies like radio receivers and optical communication systems.