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Demodulation is the process of 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, and there are many types of ...
A lock in amplifier uses a multiplier and a low pass filter to compare a reference signal against a noisy signal. A lock-in amplifier is a type of amplifier that can extract a signal with a known carrier wave from an extremely noisy environment. Depending on the dynamic reserve of the instrument, signals up to a million times smaller than noise ...
Delta-sigma (ΔΣ; or sigma-delta, ΣΔ) modulation is an oversampling method for encoding signals into low bit depth digital signals at a very high sample-frequency as part of the process of delta-sigma analog-to-digital converters (ADCs) and digital-to-analog converters (DACs).
The demodulator's bandwidth depends on the Q factor of the resonant circuit; the phase response of the secondary (and therefore, the voltage response of the circuit) to is an S-curve. Foster–Seeley discriminators are sensitive to both frequency and amplitude variations, unlike some detectors.
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 to baseband using a single mixing stage.
In communication circuits, a very common task is to separate out, or extract, signals or components of a signal that are close together in frequency. This is called filtering . Some examples are: picking up a radio station among several that are close in frequency, or extracting the chrominance subcarrier from a TV signal.
When it is applied to a typical (linear time-invariant) circuit or device, it causes a current that is also sinusoidal. In general there is a constant phase difference φ between any two sinusoids. The input sinusoidal voltage is usually defined to have zero phase, meaning that it is arbitrarily chosen as a convenient time reference.
The group delay and phase delay properties of a linear time-invariant (LTI) system are functions of frequency, giving the time from when a frequency component of a time varying physical quantity—for example a voltage signal—appears at the LTI system input, to the time when a copy of that same frequency component—perhaps of a different physical phenomenon—appears at the LTI system output.