what is baseband

In telecommunications and signal processing, baseband refers to the range of frequencies occupied by a signal that has not been modulated to higher frequencies. A baseband signal may have frequency components going all the way down to the DC bias, or at least it will have a high ratio bandwidth. A modulated baseband signal is called a passband signal, which occupies a higher range of frequencies and has a lower ratio and fractional bandwidth. Baseband communication systems have been in use for many years and are still used in technologies such as Ethernet and wireless communications. Baseband technology is used in various types of networks, including Ethernet and token ring local area networks. A baseband channel or lowpass channel is a communication channel that can transfer frequencies that are very near zero. Examples of baseband signals include the output of an analog microphone and Ethernet transmission.