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A modulator-demodulator, commonly referred to as a modem, is a computer hardwaredevice that converts data from a digital formatinto a format suitable for an analog transmission mediumsuch as telephone or radio. A modem transmits data by modulatingone or more carrier wavesignals to encode digital information, while the receiver demodulatesthe ...
Passband modulation. In electronics and telecommunications, modulation is the process of varying one or more properties of a periodic waveform, called the carrier signal, with a separate signal called the modulation signal that typically contains information to be transmitted. [1] For example, the modulation signal might be an audio signal ...
Demodulation is extracting the original information-bearing signal from a carrier wave. A demodulator is an electronic circuit (or computer program in a software-defined radio) that is used to recover the information content from the modulated carrier wave. [1] There are many types of modulation so there are many types of demodulators.
Software-defined radio (SDR) is a radio communication system where components that conventionally have been implemented in analog hardware (e.g. mixers, filters, amplifiers, modulators / demodulators, detectors, etc.) are instead implemented by means of software on a computer or embedded system. [1] While the concept of SDR is not new, the ...
FDM. Multiplexing. v. t. e. Phase-shift keying (PSK) is a digital modulation process which conveys data by changing (modulating) the phase of a constant frequency carrier wave. The modulation is accomplished by varying the sine and cosine inputs at a precise time. It is widely used for wireless LANs, RFID and Bluetooth communication.
Contents. Orthogonal frequency-division multiplexing. In telecommunications, orthogonal frequency-division multiplexing (OFDM) is a type of digital transmission used in digital modulation for encoding digital (binary) data on multiple carrier frequencies. OFDM has developed into a popular scheme for wideband digital communication, used in ...
Passband modulation. In radio communications, single-sideband modulation (SSB) or single-sideband suppressed-carrier modulation (SSB-SC) is a type of modulation used to transmit information, such as an audio signal, by radio waves. A refinement of amplitude modulation, it uses transmitter power and bandwidth more efficiently.
At the receiver, a demodulation process is performed to recover the data. The properties of this class of codes allow many users (with different codes) to use the same radio channel at the same time. To the receiver, the signals of other users will appear to the demodulator only as a low-level noise. [citation needed]