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Pulsed Radar
Pulse compression is a signal processing technique commonly used by radar, sonar and echography to either increase the range resolution when pulse length is constrained or increase the signal to noise ratio when the peak power and the bandwidth (or equivalently range resolution) of the transmitted signal are constrained. This is achieved by modulating the transmitted pulse and then correlating the received signal with the transmitted pulse. Simple pulse Signal description The ideal model for the simplest, and historically first type of signals a pulse radar or sonar can transmit is a truncated sinusoidal pulse (also called a CW --carrier wave-- pulse), of amplitude A and carrier frequency, f_0, truncated by a rectangular function of width, T. The pulse is transmitted periodically, but that is not the main topic of this article; we will consider only a single pulse, s. If we assume the pulse to start at time t=0, the signal can be written the following way, using the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Signal Processing
Signal processing is an electrical engineering subfield that focuses on analyzing, modifying and synthesizing ''signals'', such as audio signal processing, sound, image processing, images, Scalar potential, potential fields, Seismic tomography, seismic signals, Altimeter, altimetry processing, and scientific measurements. Signal processing techniques are used to optimize transmissions, Data storage, digital storage efficiency, correcting distorted signals, improve subjective video quality, and to detect or pinpoint components of interest in a measured signal. History According to Alan V. Oppenheim and Ronald W. Schafer, the principles of signal processing can be found in the classical numerical analysis techniques of the 17th century. They further state that the digital refinement of these techniques can be found in the digital control systems of the 1940s and 1950s. In 1948, Claude Shannon wrote the influential paper "A Mathematical Theory of Communication" which was publis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Cross-correlation
In signal processing, cross-correlation is a measure of similarity of two series as a function of the displacement of one relative to the other. This is also known as a ''sliding dot product'' or ''sliding inner-product''. It is commonly used for searching a long signal for a shorter, known feature. It has applications in pattern recognition, single particle analysis, electron tomography, averaging, cryptanalysis, and neurophysiology. The cross-correlation is similar in nature to the convolution of two functions. In an autocorrelation, which is the cross-correlation of a signal with itself, there will always be a peak at a lag of zero, and its size will be the signal energy. In probability and statistics, the term ''cross-correlations'' refers to the correlations between the entries of two random vectors \mathbf and \mathbf, while the ''correlations'' of a random vector \mathbf are the correlations between the entries of \mathbf itself, those forming the correlation mat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
After Matched Filter No Noise
After may refer to: Literature * ''After'' (Elgar), an 1895 poem by Philip Bourke Marston set to music by Edward Elgar * ''After'' (Prose novel), a 2003 novel by Francine Prose * ''After'' (Chalifour book), a 2005 book by Canadian writer Francis Chalifour * ''After'' (Todd novel), a 2013 novel by Anna Todd *'' After: A Doctor Explores What Near-Death Experiences Reveal about Life and Beyond'', a 2021 book by Bruce Greyson Music * ''After'' (Elgar), a poem by P. B. Marston set to music by Edward Elgar, 1895 * ''After'' (Ihsahn album), 2010 * ''After'' (Lady Lamb album), 2015 * ''After'' (Mount Eerie album), 2018 *''After'', a 1995 album by Sammi Cheng *"After", a 2011 song by Moby from Destroyed *"After", a 2023 song by Pabllo Vittar from Noitada *"After", a 2014 song by Amy Lee featuring Dave Eggar from the album ''Aftermath'' TV and film * After (2009 film), a Spanish drama film * ''After'' (2012 film), a sci-fi thriller film written and directed by Ryan Smith * ''After'', ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Hann Function
The Hann function is named after the Austrian meteorologist Julius von Hann. It is a window function used to perform Hann smoothing or hanning. The function, with length L and amplitude 1/L, is given by: : w_0(x) \triangleq \left\. For digital signal processing, the function is sampled symmetrically (with spacing L/N and amplitude 1): : \left . \begin w[n] = L\cdot w_0\left(\tfrac (n-N/2)\right) &= \tfrac \left[1 - \cos \left ( \tfrac \right) \right]\\ &= \sin^2 \left ( \tfrac \right) \end \right \},\quad 0 \leq n \leq N, which is a sequence of N+1 samples, and N can be even or odd. It is also known as the raised cosine window, Hann filter, von Hann window, Hanning window, etc. Fourier transform The Fourier transform of w_0(x) is given by: :W_0(f) = \frac\frac = \frac Discrete transforms The Discrete-time Fourier transform (DTFT) of the N+1 length, time-shifted sequence is defined by a Fourier series, which also has a 3-term equivalent that is der ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Hamming Window
In signal processing and statistics, a window function (also known as an apodization function or tapering function) is a function (mathematics), mathematical function that is zero-valued outside of some chosen interval (mathematics), interval. Typically, window functions are symmetric around the middle of the interval, approach a maximum in the middle, and taper away from the middle. Mathematically, when another function or waveform/data-sequence is "multiplied" by a window function, the product is also zero-valued outside the interval: all that is left is the part where they overlap, the "view through the window". Equivalently, and in actual practice, the segment of data within the window is first isolated, and then only that data is multiplied by the window function values. Thus, tapering, not segmentation, is the main purpose of window functions. The reasons for examining segments of a longer function include detection of transient events and time-averaging of frequency spec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Sidelobe
In antenna engineering, sidelobes are the lobes (local maxima) of the far field radiation pattern of an antenna or other radiation source, that are not the ''main lobe''. The radiation pattern of most antennas shows a pattern of "''lobes''" at various angles, directions where the radiated signal strength reaches a maximum, separated by "''nulls''", angles at which the radiated signal strength falls to zero. This can be viewed as the diffraction pattern of the antenna. In a directional antenna in which the objective is to emit the radio waves in one direction, the lobe in that direction is designed to have a larger field strength than the others; this is the "''main lobe''". The other lobes are called "''sidelobes''", and usually represent unwanted radiation in undesired directions. The sidelobe directly behind the main lobe is called the back lobe. The longer the antenna relative to the radio wavelength, the more lobes its radiation pattern has. In transmitting antennas, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Sinc
In mathematics, physics and engineering, the sinc function ( ), denoted by , has two forms, normalized and unnormalized.. In mathematics, the historical unnormalized sinc function is defined for by \operatorname(x) = \frac. Alternatively, the unnormalized sinc function is often called the sampling function, indicated as Sa(''x''). In digital signal processing and information theory, the normalized sinc function is commonly defined for by \operatorname(x) = \frac. In either case, the value at is defined to be the limiting value \operatorname(0) := \lim_\frac = 1 for all real (the limit can be proven using the squeeze theorem). The normalization causes the definite integral of the function over the real numbers to equal 1 (whereas the same integral of the unnormalized sinc function has a value of ). As a further useful property, the zeros of the normalized sinc function are the nonzero integer values of . The normalized sinc function is the Fourier transform of the r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Rectangle Function
The rectangular function (also known as the rectangle function, rect function, Pi function, Heaviside Pi function, gate function, unit pulse, or the normalized boxcar function) is defined as \operatorname\left(\frac\right) = \Pi\left(\frac\right) = \left\{\begin{array}{rl} 0, & \text{if } , t, > \frac{a}{2} \\ \frac{1}{2}, & \text{if } , t, = \frac{a}{2} \\ 1, & \text{if } , t, \frac{1}{2} \\ \frac{1}{2} & \mbox{if } , t, = \frac{1}{2} \\ 1 & \mbox{if } , t, < \frac{1}{2}. \\ \end{cases} Dirac delta function The rectangle function can be used to represent the . Specifically,For a function , its average over the wi ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Chirp
A chirp is a signal in which the frequency increases (''up-chirp'') or decreases (''down-chirp'') with time. In some sources, the term ''chirp'' is used interchangeably with sweep signal. It is commonly applied to sonar, radar, and laser systems, and to other applications, such as in spread-spectrum communications (see chirp spread spectrum). This signal type is biologically inspired and occurs as a phenomenon due to dispersion (a non-linear dependence between frequency and the propagation speed of the wave components). It is usually compensated for by using a matched filter, which can be part of the propagation channel. Depending on the specific performance measure, however, there are better techniques both for radar and communication. Since it was used in radar and space, it has been adopted also for communication standards. For automotive radar applications, it is usually called linear frequency modulated waveform (LFMW). In spread-spectrum usage, surface acoustic wave (S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Merged Signal After Matched Filter
Mergers and acquisitions (M&A) are business transactions in which the ownership of a company, business organization, or one of their operating units is transferred to or consolidated with another entity. They may happen through direct absorption, a merger, a tender offer or a hostile takeover. As an aspect of strategic management, M&A can allow enterprises to grow or downsize, and change the nature of their business or competitive position. Technically, a is the legal consolidation of two business entities into one, whereas an occurs when one entity takes ownership of another entity's share capital, equity interests or assets. From a legal and financial point of view, both mergers and acquisitions generally result in the consolidation of assets and liabilities under one entity, and the distinction between the two is not always clear. Most countries require mergers and acquisitions to comply with antitrust or competition law. In the United States, for example, the Clayton ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
CW Signals Close In Time Before Matched Filtering
CW may stand for: Science and technology * centiwatt (cW), one hundredth of a watt * Cω, a programming language * CW complex, a type of topological space * Carrier wave, in radio communications * CodeWarrior, an integrated development environment by Metrowerks * Constructed wetland, a man-made wetland to treat wastewater * Continuous wave, a method of radio transmission (telegraphy) that carries Morse code, and a microwave theory * ClarisWorks, an office suite now known as AppleWorks * Drag coefficient, a measure of air resistance commonly denoted \mathbf c_\mathrm w\, * Contention Window, a network traffic technique * chemical formula of tungsten carbide Arts and media Gaming * ''Castle Wolfenstein'', a 1981 video game * ''Cube World'', a video game Publications * ''Computerworld'', an information technology magazine * ''The Crimson White'', a student-run newspaper of the University of Alabama Other media * The CW, an American television network/programming service **The CW ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
