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Squegging
Squegging is a radio engineering term. It is a contraction of self-quenching. A squegging or ''self-blocking'' oscillator produces an intermittent or changing output signal. Wildlife tags for birds and little mammals use squegging oscillators. The Armstrong super-regenerative radio receiver uses a self-blocking oscillator, too. The receiver sensitivity rises while the oscillation builds up. The oscillation stops when the operation point no longer fulfills the Barkhausen stability criterion. The blocking oscillator recovers to the initial state and the cycle starts again. The receive frequency of the Armstrong Super-Regenerative receiver was some hundred kilohertz. The self-quenching frequency was ten kilohertz, just above the highest audio frequency the headphone could reproduce. Squegging is an oscillation that builds up and dies down with a much longer time constant than the fundamental frequency The fundamental frequency, often referred to simply as the ''fundamental'', is de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Regenerative Circuit
A regenerative circuit is an amplifier circuit that employs positive feedback (also known as regeneration or reaction). Some of the output of the amplifying device is applied back to its input so as to add to the input signal, increasing the amplification. One example is the Schmitt trigger (which is also known as a regenerative comparator), but the most common use of the term is in RF amplifiers, and especially regenerative receivers, to greatly increase the gain of a single amplifier stage. The regenerative receiver was invented in 1912 and patented in 1914US Patent 1113149A, Edwin H. Armstrong, Wireless receiving system', filed October 29, 1913, granted October 6, 1914 by American electrical engineer Edwin Armstrong when he was an undergraduate at Columbia University. It was widely used between 1915 and World War II. Advantages of regenerative receivers include increased sensitivity with modest hardware requirements, and increased selectivity because the Q of the tuned ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oscillation
Oscillation is the repetitive or periodic variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states. Familiar examples of oscillation include a swinging pendulum and alternating current. Oscillations can be used in physics to approximate complex interactions, such as those between atoms. Oscillations occur not only in mechanical systems but also in dynamic systems in virtually every area of science: for example the beating of the human heart (for circulation), business cycles in economics, predator–prey population cycles in ecology, geothermal geysers in geology, vibration of strings in guitar and other string instruments, periodic firing of nerve cells in the brain, and the periodic swelling of Cepheid variable stars in astronomy. The term ''vibration'' is precisely used to describe a mechanical oscillation. Oscillation, especially rapid oscillation, may be an undesirable phenomenon in proc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barkhausen Stability Criterion
In electronics, the Barkhausen stability criterion is a mathematical condition to determine when a linear electronic circuit will oscillate. It was put forth in 1921 by German physicist Heinrich Georg Barkhausen (1881–1956). It is widely used in the design of electronic oscillators, and also in the design of general negative feedback circuits such as op amps, to prevent them from oscillating. Limitations Barkhausen's criterion applies to linear circuits with a feedback loop. It cannot be applied directly to active elements with negative resistance like tunnel diode oscillators. The kernel of the criterion is that a complex pole pair must be placed on the imaginary axis of the complex frequency plane if steady state oscillations should take place. In the real world, it is impossible to balance on the imaginary axis, so in practice a steady-state oscillator is a non-linear circuit: * It needs to have positive feedback. * The loop gain is at unity (, \beta A, = 1\,). Cr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Time Constant
In physics and engineering, the time constant, usually denoted by the Greek letter (tau), is the parameter characterizing the response to a step input of a first-order, linear time-invariant (LTI) system.Concretely, a first-order LTI system is a system that can be modeled by a single first order differential equation in time. Examples include the simplest single-stage electrical RC circuits and RL circuits. The time constant is the main characteristic unit of a first-order LTI system. In the time domain, the usual choice to explore the time response is through the step response to a step input, or the impulse response to a Dirac delta function input. In the frequency domain (for example, looking at the Fourier transform of the step response, or using an input that is a simple sinusoidal function of time) the time constant also determines the bandwidth of a first-order time-invariant system, that is, the frequency at which the output signal power drops to half the value it has at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fundamental Frequency
The fundamental frequency, often referred to simply as the ''fundamental'', is defined as the lowest frequency of a periodic waveform. In music, the fundamental is the musical pitch of a note that is perceived as the lowest partial present. In terms of a superposition of sinusoids, the fundamental frequency is the lowest frequency sinusoidal in the sum of harmonically related frequencies, or the frequency of the difference between adjacent frequencies. In some contexts, the fundamental is usually abbreviated as 0, indicating the lowest frequency counting from zero. In other contexts, it is more common to abbreviate it as 1, the first harmonic. (The second harmonic is then 2 = 2⋅1, etc. In this context, the zeroth harmonic would be 0 Hz.) According to Benward's and Saker's ''Music: In Theory and Practice'': Explanation All sinusoidal and many non-sinusoidal waveforms repeat exactly over time – they are periodic. The period of a waveform is the smallest value of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Motorboating (electronics)
In electronics, motorboating is a type of low frequency parasitic oscillation (unwanted cyclic variation of the output voltage) that sometimes occurs in audio and radio equipment and often manifests itself as a sound similar to an idling motorboat engine, a "put-put-put", in audio output from speakers or earphones. It is a problem encountered particularly in radio transceivers and older vacuum tube audio systems, guitar amplifiers, PA systems and is caused by some type of unwanted feedback in the circuit. The amplifying devices in audio and radio equipment are vulnerable to a variety of feedback problems, which can cause distinctive noise in the output. The term motorboating is applied to oscillations whose frequency is below the range of hearing, from 1 to 10 hertz, so the individual oscillations are heard as pulses. Sometimes the oscillations can even be seen visually as the woofer cones in speakers slowly moving in and out. Besides sounding annoying, motorboating can cause cl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AI Mk
AI is artificial intelligence, intellectual ability in machines and robots. Ai, AI or A.I. may also refer to: Animals * Ai (chimpanzee), an individual experimental subject in Japan * Ai (sloth) or the pale-throated sloth, northern Amazonian mammal species Arts, entertainment and media Works * ''Ai'' (album), a 2004 release by Seraphim * ''A.I. Artificial Intelligence'', a 2001 American film * '' A.I. Rising'', a 2018 Serbian film * '' AI: The Somnium Files'', a 2019 video game * ''American Idol'', televised singing contest * ''The American Interest'', a bimonthly magazine (2005–2020) * ''I'' (2015 film), an Indian Tamil film (initial title: ''Ai'') Other uses in arts and media * A.i. (band), a Californian rock–electroclash group * All in (poker), wagering one's entire stake * Appreciation Index, a British measure of broadcast programme approval * The Art Institutes, a chain of American art schools * Non-player character, in gaming (colloquially, ''an AI'') Business * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
