Baseband

In telecommunications and signal processing, baseband is an adjective that describes signals and systems whose range of frequencies is measured from close to 0 hertz to a cut-off frequency, a maximum bandwidth or highest signal frequency; it is sometimes used as a noun for a band of frequencies starting close to zero. Baseband can often be considered a synonym to lowpass or non-modulated, and antonym to passband, bandpass, carrier-modulated or radio frequency (RF). The term is often used in contrast to passband, which refers to a signal which has been translated to a higher frequency, often for transmission by frequency division multiplexing.