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Quadrature Decoder
Quadrature may refer to: Mathematics * Quadrature (geometry), drawing a square with the same area as a given plane figure (''squaring'') or computing that area ** Quadrature of the circle ** ''Quadrature of the Parabola'' ** Quadrature of the hyperbola * Numerical integration is often called "numerical quadrature" or simply "quadrature" ** Gaussian quadrature, a special case of numerical integration * Quadrature (differential equations), expressing a differential equation solution in terms of integrals. * Formerly, a synonym for "integral" ** Integral ** Antiderivative Signal processing * Addition in quadrature, combining the magnitude of uncorrelated signals by taking the square root of the sum of their squares *Quadrature phase, oscillations that are said to be ''in quadrature'' if they are separated in phase by 90° (/2, or /4) *Quadrature component of a composite signal *Quadrature filter, the analytic signal of a real-valued filter *Quadrature amplitude modulation (QAM), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quadrature (geometry)
In mathematics, quadrature is a historic term for the computation of area (mathematics), areas and is thus used for computation of integrals. The word is derived from the Latin ''quadratus'' meaning "square". The reason is that, for Ancient Greek mathematicians, the computation of an area consisted of constructing a square of the same area. In this sense, the modern term is squaring. For example, the quadrature of the circle, (or squaring the circle) is a famous old problem that has been shown, in the 19th century, to be impossible with the methods available to the Ancient Greeks, Integral calculus, introduced in the 17th century, is a general method for computation of areas. ''Quadrature'' came to refer to the computation of any integral; such a computation is presently called more often "integral" or "integration". However, the computation of solutions of differential equations and differential systems is also called ''integration'', and ''quadrature'' remains useful for dist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quadrature Component
A sinusoid with modulation can be decomposed into, or synthesized from, two amplitude-modulated sinusoids that are in quadrature phase, i.e., with a phase offset of one-quarter cycle (90 degrees or /2 radians). All three sinusoids have the same center frequency. The two amplitude-modulated sinusoids are known as the in-phase (I) and quadrature (Q) components, which describes their relationships with the amplitude- and phase-modulated carrier. Or in other words, it is possible to create an arbitrarily phase-shifted sine wave, by mixing together two sine waves that are 90° out of phase in different proportions. The implication is that the modulations in some signal can be treated separately from the carrier wave of the signal. This has extensive use in many radio and signal processing applications. I/Q data is used to represent the modulations of some carrier, independent of that carrier's frequency. Orthogonality In vector analysis, a vector with polar coordinates and Car ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Illusionistic Ceiling Painting
Illusionistic ceiling painting, which includes the techniques of perspective di sotto in sù and quadratura, is the tradition in Renaissance, Baroque and Rococo art in which '' trompe-l'œil'', perspective tools such as foreshortening, and other spatial effects are used to create the illusion of three-dimensional space on an otherwise two-dimensional or mostly flat ceiling surface above the viewer. It is frequently used to create the illusion of an open sky, such as with the oculus in Andrea Mantegna's Camera degli Sposi, or the illusion of an architectural space such as the cupola, one of Andrea Pozzo's frescoes in Sant'Ignazio, Rome. Illusionistic ceiling painting belongs to the general class of illusionism in art, designed to create accurate representations of reality. Di sotto in sù ''Di sotto in sù'' (or ''sotto in su''), which means "seen from below" or "from below, upward" in Italian, developed in late quattrocento Italian Renaissance painting, notably in Andrea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quadrature Encoder
An incremental encoder is a linear or rotary electromechanical device that has two output signals, ''A'' and ''B'', which issue pulses when the device is moved. Together, the ''A'' and ''B'' signals indicate both the occurrence of and direction of movement. Many incremental encoders have an additional output signal, typically designated ''index'' or ''Z'', which indicates the encoder is located at a particular reference position. Also, some encoders provide a status output (typically designated ''alarm'') that indicates internal fault conditions such as a bearing failure or sensor malfunction. Unlike an absolute encoder, an incremental encoder does not indicate absolute position; it only reports changes in position and the corresponding direction of movement for each change. Consequently, to determine absolute position at any particular moment, it is necessary to send the encoder signals to an '' incremental encoder interface'', which in turn will "track" and report the encoder ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quadrature (astronomy)
In spherical astronomy, quadrature is the configuration of a celestial object in which its elongation is a right angle (90 degrees), i.e., the direction of the object as viewed from Earth is perpendicular to the position of the Sun relative to Earth. It is applied especially to the position of a superior planet or the Moon at its first and last quarter phases. This is not to be confused with the Moon at dichotomy (exactly half-lit) as viewed from Earth, which occurs at 89.85 degrees and 270.15 degrees. As shown in the diagram, a planet (or other object) can be at the western quadrature (when it is to the west of the Sun when viewed from the Earth) or at the eastern quadrature (when it is to the east of the Sun when viewed from the Earth). Note that an inferior planet can never be at quadrature to the reference planet. At quadrature, the shadow that a planet casts on its planetary rings or moons appears most offset from the planet (e.g., Saturn's rings); the dark side of a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Phase Space
In quantum optics, an optical phase space is a phase space in which all quantum states of an optical system are described. Each point in the optical phase space corresponds to a unique state of an ''optical system''. For any such system, a plot of the ''quadratures'' against each other, possibly as functions of time, is called a phase diagram. If the quadratures are functions of time then the optical phase diagram can show the evolution of a quantum optical system with time. An optical phase diagram can give insight into the properties and behaviors of the system that might otherwise not be obvious. This can allude to qualities of the system that can be of interest to an individual studying an optical system that would be very hard to deduce otherwise. Another use for an optical phase diagram is that it shows the evolution of the state of an optical system. This can be used to determine the state of the optical system at any point in time. Background information When discussing t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quadrature Phase-shift Keying
Phase-shift keying (PSK) is a digital modulation process which conveys data by changing (modulating) the phase of a constant frequency carrier wave. 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. Usually, each phase encodes an equal number of bits. Each pattern of bits forms the symbol that is represented by the particular phase. The demodulator, which is designed specifically for the symbol-set used by the modulator, determines the phase of the received signal and maps it back to the symbol it represents, thus recovering the original data. This requires the receiver to be able to compare the phase of the received signal to a reference signal such a system is termed coherent (and refer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quadrature Amplitude Modulation
Quadrature amplitude modulation (QAM) is the name of a family of digital modulation methods and a related family of analog modulation methods widely used in modern telecommunications to transmit information. It conveys two analog message signals, or two digital bit streams, by changing (''modulating'') the amplitudes of two carrier waves, using the amplitude-shift keying (ASK) digital modulation scheme or amplitude modulation (AM) analog modulation scheme. The two carrier waves are of the same frequency and are out of phase with each other by 90°, a condition known as orthogonality or Quadrature phase, quadrature. The transmitted signal is created by adding the two carrier waves together. At the receiver, the two waves can be coherently separated (demodulated) because of their orthogonality. Another key property is that the modulations are low-frequency/low-bandwidth waveforms compared to the carrier frequency, which is known as the In-phase and quadrature components#Narrowband ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quadrature Filter
In signal processing, a quadrature filter q(t) is the analytic representation of the impulse response f(t) of a real-valued filter: : q(t) = f_(t) = \left(\delta(t) + j\delta(jt) \right) * f(t) If the quadrature filter q(t) is applied to a signal s(t), the result is : h(t) = (q * s)(t) = \left(\delta(t) + j\delta(jt)\right) * f(t) * s(t) which implies that h(t) is the analytic representation of (f * s)(t). Since q is an analytic signal, it is either zero or complex-valued. In practice, therefore, q is often implemented as two real-valued filters, which correspond to the real and imaginary parts of the filter, respectively. An ideal quadrature filter cannot have a finite support. It has single sided support, but by choosing the (analog) function f(t) carefully, it is possible to design quadrature filters which are localized such that they can be approximated by means of functions of finite support. A digital realization without feedback (FIR) has finite support. Applicati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quadrature Phase
In physics and mathematics, the phase (symbol φ or ϕ) of a wave or other periodic function F of some real variable t (such as time) is an angle-like quantity representing the fraction of the cycle covered up to t. It is expressed in such a scale that it varies by one full turn as the variable t goes through each period (and F(t) goes through each complete cycle). It may be measured in any angular unit such as degrees or radians, thus increasing by 360° or 2\pi as the variable t completes a full period. This convention is especially appropriate for a sinusoidal function, since its value at any argument t then can be expressed as \varphi(t), the sine of the phase, multiplied by some factor (the amplitude of the sinusoid). (The cosine may be used instead of sine, depending on where one considers each period to start.) Usually, whole turns are ignored when expressing the phase; so that \varphi(t) is also a periodic function, with the same period as F, that repeatedly sca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quadrature Of The Circle
Squaring the circle is a problem in geometry first proposed in Greek mathematics. It is the challenge of constructing a square (geometry), square with the area of a circle, area of a given circle by using only a finite number of steps with a compass and straightedge. The difficulty of the problem raised the question of whether specified axioms of Euclidean geometry concerning the existence of Line (geometry), lines and circles implied the existence of such a square. In 1882, the task was proven to be impossible, as a consequence of the Lindemann–Weierstrass theorem, which proves that pi (\pi) is a transcendental number. That is, \pi is not the zero of a function, root of any polynomial with Rational number, rational coefficients. It had been known for decades that the construction would be impossible if \pi were transcendental, but that fact was not proven until 1882. Approximate constructions with any given non-perfect accuracy exist, and many such constructions have been f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Addition In Quadrature
In mathematics, Pythagorean addition is a binary operation on the real numbers that computes the length of the hypotenuse of a right triangle, given its two sides. Like the more familiar addition and multiplication operations of arithmetic, it is both associative and commutative. This operation can be used in the conversion of Cartesian coordinates to polar coordinates, and in the calculation of Euclidean distance. It also provides a simple notation and terminology for the diameter of a cuboid, the energy-momentum relation in physics, and the overall noise from independent sources of noise. In its applications to signal processing and propagation of measurement uncertainty, the same operation is also called addition in quadrature. A scaled version of this operation gives the quadratic mean or ''root mean square''. It is implemented in many programming libraries as the hypot function, in a way designed to avoid errors arising due to limited-precision calculations performed on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
