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Amplitude and phase-shift keying (APSK) is a digital modulation scheme that conveys data by modulating both the amplitude and the phase of a carrier wave. In other words, it combines both amplitude-shift keying (ASK) and phase-shift keying (PSK).
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]
A constellation diagram is a representation of a signal modulated by a digital modulation scheme such as quadrature amplitude modulation or phase-shift keying. [1] It displays the signal as a two-dimensional xy-plane scatter diagram in the complex plane at symbol sampling instants.
The goal of keying is to transmit a digital signal over an analog channel. The name derives from the Morse code key used for telegraph signaling. Modulation is the general technique of shaping a signal to convey information. When a digital message has to be represented as an analog waveform, the technique and term keying (or digital modulation ...
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. Any digital modulation scheme uses a finite number of distinct signals to represent digital data. PSK uses a finite number of phases, each assigned a unique pattern of binary digits ...
Orthogonal frequency-division multiple access (OFDMA) is a multi-user version of the popular orthogonal frequency-division multiplexing (OFDM) digital modulation scheme. Multiple access is achieved in OFDMA by assigning subsets of subcarriers to individual users. This allows simultaneous low-data-rate transmission from several users.
An example of binary FSK. Frequency-shift keying (FSK) is a frequency modulation scheme in which digital information is encoded on a carrier signal by periodically shifting the frequency of the carrier between several discrete frequencies. [1]
Spectral efficiency of MFSK modulation schemes decreases with increasing of modulation order M: [1] ρ = 2 log 2 M M {\displaystyle \rho ={\frac {2\log _{2}M}{M}}} Like any other form of angle modulation that transmits a single RF tone that varies only in phase or frequency, MFSK produces a constant envelope .