Tech Dictionary
Found 45 records.
A digital modulation scheme that conveys data by changing (modulating) the amplitude of two carrier waves, using 16 distinct symbols in the constellation diagram
A more dense digital modulation scheme than 16-QAM, using 64 distinct symbols to transmit more data per symbol period
Amplitude Modulation (AM)
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A modulation technique used in electronic communication, most commonly for transmitting messages with a radio wave, where the amplitude of the carrier wave is varied
Amplitude Shift Keying (ASK)
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A form of amplitude modulation that represents digital data as variations in the amplitude of a carrier wave
Analog Modulation
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The process of transferring an analog signal (like audio or video) over an analog carrier wave
Bandwidth Efficiency
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The information rate that can be transmitted over a given bandwidth in a specific communication system
Binary Phase Shift Keying (BPSK)
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A digital modulation scheme that conveys data by changing the phase of a carrier wave using two distinct phases separated by 180 degrees
Carrier Wave
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A waveform (usually sinusoidal) that is modulated (modified) with an input signal for the purpose of conveying information
Code Division Multiple Access (CDMA)
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A channel access method used by various radio communication technologies where several transmitters can send information simultaneously over a single communication channel
Constellation Diagram
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A representation of a signal modulated by a digital modulation scheme such as QAM or PSK, displaying the signal as a two-dimensional scatter diagram in the complex plane
Continuous Phase Modulation (CPM)
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A method of modulation of data that is commonly used in wireless modems, where the phase of the carrier signal is modulated in a continuous manner
Demodulation
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The process of extracting the original information-bearing signal from a carrier wave
Digital Modulation
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The process of transferring a digital bit stream over an analog channel
Direct Sequence Spread Spectrum (DSSS)
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A spread spectrum modulation technique used for digital signal transmission over airwaves, where the original data signal is multiplied by a pseudo-random noise spreading code
Frequency Division Multiplexing (FDM)
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A technique by which the total bandwidth available in a communication medium is divided into a series of non-overlapping frequency bands, each of which is used to carry a separate signal
Frequency Hopping Spread Spectrum (FHSS)
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A method of transmitting radio signals by rapidly changing the carrier frequency among many distinct frequencies occupying a large spectral band
Frequency Modulation (FM)
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A method of impressing data onto an alternating-current wave by varying the instantaneous frequency of the wave
Frequency Shift Keying (FSK)
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A frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier signal
Gaussian Minimum Shift Keying (GMSK)
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A form of continuous-phase frequency-shift keying having no phase discontinuities, used notably in GSM
In-phase/Quadrature (I/Q)
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The decomposition of a signal into two components: an in-phase component and a quadrature component (90 degrees out of phase)
Minimum Shift Keying (MSK)
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A type of continuous-phase frequency-shift keying that is encoded with bits alternating between quadrature components, with the Q component delayed by half the symbol period
Modulation
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The process of varying one or more properties of a periodic waveform, called the carrier signal, with a modulating signal that contains information to be transmitted
Modulation Index
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A measure of the extent of modulation done to a carrier signal
Multiplexing
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A method by which multiple analog or digital signals are combined into one signal over a shared medium
Noise
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Unwanted disturbances superimposed on a useful signal that tend to obscure its information content