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Categorization for signal modulation based on data and carrier types. 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]
The receiver is designed so that either code word of the pair decodes to the same data bits. Examples include alternate mark inversion, Differential Manchester encoding, coded mark inversion and Miller encoding. differential coding each symbol relative to the previous symbol. Examples include MLT-3 encoding and NRZI.
(CF c is 3.01 dB for the sine waves used for BPSK and QPSK modulation). For example, the DVB-T signal in 2K mode is composed of 1705 subcarriers that are each QPSK-modulated, giving a crest factor of 35.32 dB. [29] Many PAPR (or crest factor) reduction techniques have been developed, for instance, based on iterative clipping. [30]
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.
Frequency modulation encoding, or simply FM, is a method of storing data that saw widespread use in early floppy disk drives and hard disk drives. The data is modified using differential Manchester encoding when written to allow clock recovery to address timing effects known as "jitter" seen on disk media.
The binary signal is encoded using rectangular pulse-amplitude modulation with polar NRZ(L), or polar non-return-to-zero-level code. In telecommunications, a non-return-to-zero (NRZ) line code is a binary code in which ones are represented by one significant condition, usually a positive voltage, while zeros are represented by some other significant condition, usually a negative voltage, with ...
Differential encoding prevents inversion of the signal and symbols, respectively, from affecting the data. Assuming that x i {\displaystyle x_{i}} is a bit intended for transmission and y i − 1 {\displaystyle y_{i-1}} was the symbol just transmitted, then the symbol to be transmitted for x i {\displaystyle x_{i}} is
When a digital signal is to be transmitted over an analogue baseband channel, the modulation technique is termed line coding. Several keying techniques exist, including phase-shift keying, frequency-shift keying, and amplitude-shift keying. Bluetooth, for example, uses phase-shift keying to exchange information between devices.