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IQ data has extensive use in many signal processing contexts, including for radio modulation, software-defined radio, audio signal processing and electrical engineering. I/Q data is a two-dimensional stream. Some sources treat I/Q as a complex number; [1] with the I and Q
Digital modulation methods can be considered as digital-to-analog conversion and the corresponding demodulation or detection as analog-to-digital conversion. The changes in the carrier signal are chosen from a finite number of M alternative symbols (the modulation alphabet). Schematic of 4 baud, 8 bit/s data link containing arbitrarily chosen ...
Polar modulation was originally developed by Thomas Edison in his 1874 quadruplex telegraph – this allowed 4 signals to be sent along a pair of lines, 2 in each direction. Sending a signal in each direction had already been accomplished earlier, and Edison found that by combining amplitude and phase modulation (i.e., by polar modulation), he ...
A diagram with four points, for example, represents a modulation scheme that can separately encode all 4 combinations of two bits: 00, 01, 10, and 11, and so can transmit two bits per symbol. Thus in general a modulation with N {\displaystyle N} constellation points transmits log 2 N {\displaystyle \log _{2}N} bits per symbol.
IQ imbalance is a performance-limiting issue in the design of a class of radio receivers known as direct conversion receivers. [ a ] These translate the received radio frequency (RF, or pass-band ) signal directly from the carrier frequency f c {\displaystyle f_{c}} to baseband using a single mixing stage.
This can also be extended to frequency modulation (FM) and frequency-shift keying (FSK), for these can be regarded as a special case of phase modulation [citation needed]. QAM is used extensively as a modulation scheme for digital communications systems, such as in 802.11 Wi-Fi standards.
In digital modulation, minimum-shift keying (MSK) is a type of continuous-phase frequency-shift keying that was developed in the late 1950s by Collins Radio employees Melvin L. Doelz and Earl T. Heald. [1] Similar to OQPSK, MSK is encoded with bits alternating between quadrature components, with the Q component delayed by half the symbol period.
Signal analyzers can perform the operations of both spectrum analyzers and vector signal analyzers.A signal analyzer can be viewed as a measurement platform, with operations such as spectrum analysis (including phase noise, power, and distortion) and vector signal analysis (including demodulation or modulation quality analysis) performed as measurement applications.