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Noise Generator
A noise generator is a circuit that produces electrical noise (i.e., a random signal). Noise generators are used to test signals for measuring noise figure, frequency response, and other parameters. Noise generators are also used for generating random numbers. Theory There are several circuits used for noise generation. For example, temperature-controlled resistors, temperature-limited vacuum diodes, zener diodes, and gas discharge tubes. A source that can be switched on and off ("gated") is beneficial for some test methods. Noise generators usually rely on a fundamental noise process such as thermal noise or shot noise. Thermal noise generator Thermal noise can be a fundamental standard. A resistor at a certain temperature has a thermal noise associated with it. A noise generator might have two resistors at different temperatures and switch between the two resistors. The resulting output power is low. (For a 1 kΩ resistor at room temperature and a 10 kHz bandwidth, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zener Diode Noise Source , cards used to conduct experiments for extra-sensory perception
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Zener can refer to: *Zener diode, a type of electronic diode *Zener effect, a type of electrical breakdown which is employed in a Zener diode *Zener pinning, the influence of a dispersion of fine particles on the movement of low- and high angle grain boundaries through a polycrystalline material *Clarence Zener, the American physicist after whom the diode, effect, and pinning are named * Karl Zener, the American psychologist after whom the cards are named **Zener cards Zener cards are cards used to conduct experiments for extrasensory perception (ESP). Perceptual psychologist Karl Zener (1903–1964) designed the cards in the early 1930s for experiments conducted with his colleague, parapsychologist J. B. Rhi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Super High Frequency
Super high frequency (SHF) is the ITU designation for radio frequencies (RF) in the range between 3 and 30 gigahertz (GHz). This band of frequencies is also known as the centimetre band or centimetre wave as the wavelengths range from one to ten centimetres. These frequencies fall within the microwave band, so radio waves with these frequencies are called microwaves. The small wavelength of microwaves allows them to be directed in narrow beams by aperture antennas such as parabolic dishes and horn antennas, so they are used for point-to-point communication and data links This article from the beginning of the microwave era predicted the future value of microwaves for point-to-point communication. and for radar. This frequency range is used for most radar transmitters, wireless LANs, satellite communication, microwave radio relay links, satellite phones (S band), and numerous short range terrestrial data links. They are also used for heating in industrial microwave heatin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electronic Test Equipment
Electronic test equipment is used to create signals and capture responses from electronic devices under test (DUTs). In this way, the proper operation of the DUT can be proven or faults in the device can be traced. Use of electronic test equipment is essential to any serious work on electronics systems. Practical electronics engineering and assembly requires the use of many different kinds of electronic test equipment ranging from the very simple and inexpensive (such as a test light consisting of just a light bulb and a test lead) to extremely complex and sophisticated such as automatic test equipment (ATE). ATE often includes many of these instruments in real and simulated forms. Generally, more advanced test gear is necessary when developing circuits and systems than is needed when doing production testing or when troubleshooting existing production units in the field. Types of test equipment Basic equipment The following items are used for basic measurement of voltages, cu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Noise Source
A radio noise source is a device that emits radio waves at a certain frequency, used to calibrate radio telescopes such that received data may be compared to a known value, as well as to find the focal point of a telescope soon after construction, so that the wave guide A waveguide is a structure that guides waves, such as electromagnetic waves or sound, with minimal loss of energy by restricting the transmission of energy to one direction. Without the physical constraint of a waveguide, wave intensities de ... and front end may be properly located. Noise {{acoustics-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Noise Figure Meter
A noise-figure meter is an instrument for measuring the noise figure of an amplifier, mixer, or similar device. An example instrument is the 1983-era Agilent 8970A8970A Noise Figure Meteris a Keysight product numbers that were formerly part of Agilent. Measurement methods One way to perform the measurement is described on the Y-factor page. A noise-figure meter could automate that procedure as follows: A gated broadband noise source (such as an avalanche diode) drives the device under test. A measurement is made with the noise source on; another measurement with the noise source off. From those measurements and the characteristics of the noise source, the noise figure can be calculated. Noise source Some noise figure meters need a calibrated broadband noise source—a noise generator. Several methods are used to generate broadband noise. Some methods require two sources: a "hot" and "cold" source. For high frequency measurements, the noise source will be embedded in a transmissi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Excess Noise Ratio
In electronics, excess noise ratio is a characteristic of a noise generator such as a "noise diode", that is used to measure the noise performance of amplifiers. The Y-factor method is a common measurement technique for this purpose. By using a noise diode, the output noise of an amplifier is measured using two input noise levels, and by measuring the output noise factor (referred to as ''Y'') the noise figure of the amplifier can be determined without having to measure the amplifier gain. Background Any amplifier generates noise. In a radio receiver the first stage dominates the overall noise of the receiver and in most cases thermal, or Johnson noise, determines the overall noise performance of a receiver. As radio signals decrease in size, the noise at the input of the receiver will determine a lower threshold of what can be received. The level of noise is determined by calculating the noise in a 50 ohm resistor at the input of the receiver as follows: : where: : = Boltzm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Keysight
Keysight Technologies, or Keysight, is an American company that manufactures electronics test and measurement equipment and software. The name is a blend of ''key'' and ''insight''. The company was formed as a spin-off of Agilent Technologies, which inherited and rebranded the test and measurement product lines developed and produced from the late 1960's to the turn of the millenium by Hewlett-Packard's Test & Measurement division. Products Keysight's products include hardware and software for benchtop, modular, and field instruments. Instruments include oscilloscopes, multimeters, logic analyzers, signal generators, spectrum analyzers, vector network analyzers, atomic force microscopes (AFM), automated optical inspection, automated X-ray inspection (5DX), in-circuit testers, power supplies, tunable lasers, optical power meters, wavelength-meters, electro-optic converters, optical modulation analyzers and handheld tools. In addition, it produces electronic design automation (EDA ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bipolar Junction Transistor
A bipolar junction transistor (BJT) is a type of transistor that uses both electrons and electron holes as charge carriers. In contrast, a unipolar transistor, such as a field-effect transistor, uses only one kind of charge carrier. A bipolar transistor allows a small current injected at one of its terminals to control a much larger current flowing between the terminals, making the device capable of amplification or switching. BJTs use two p–n junctions between two semiconductor types, n-type and p-type, which are regions in a single crystal of material. The junctions can be made in several different ways, such as changing the doping of the semiconductor material as it is grown, by depositing metal pellets to form alloy junctions, or by such methods as diffusion of n-type and p-type doping substances into the crystal. The superior predictability and performance of junction transistors quickly displaced the original point-contact transistor. Diffused transistors, along wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Avalanche Breakdown
Avalanche breakdown (or avalanche effect) is a phenomenon that can occur in both insulating and semiconducting materials. It is a form of electric current multiplication that can allow very large currents within materials which are otherwise good insulators. It is a type of electron avalanche. The avalanche process occurs when carriers in the transition region are accelerated by the electric field to energies sufficient to create mobile or free electron-hole pairs via collisions with bound electrons. Explanation Materials conduct electricity if they contain mobile charge carriers. There are two types of charge carriers in a semiconductor: free electrons (mobile electrons) and electron holes (mobile holes which are missing electrons from the normally occupied electron states). A normally bound electron (e.g., in a bond) in a reverse-biased diode may break loose due to a thermal fluctuation or excitation, creating a mobile electron-hole pair. If there is a voltage gradient (el ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zener Effect
In electronics, the Zener effect (employed most notably in the appropriately named Zener diode) is a type of electrical breakdown, discovered by Clarence Melvin Zener. It occurs in a reverse biased p-n diode when the electric field enables tunneling of electrons from the valence to the conduction band of a semiconductor, leading to numerous free minority carriers which suddenly increase the reverse current. Mechanism Under a high reverse-bias voltage, the p-n junction's depletion region widens which leads to a high-strength electric field across the junction."Zener and Avalanche Breakdown/Diodes" School of Engineering and Applied Sciences, Harvard University Sufficiently strong electric fields enable tunneling of electrons across the depletion region of a |
Thyratron
A thyratron is a type of gas-filled tube used as a high-power electrical switch and controlled rectifier. Thyratrons can handle much greater currents than similar hard-vacuum tubes. Electron multiplication occurs when the gas becomes ionized, producing a phenomenon known as Townsend discharge. Gases used include mercury vapor, xenon, neon, and (in special high-voltage applications or applications requiring very short switching times) hydrogen. Unlike a vacuum tube (valve), a thyratron cannot be used to amplify signals linearly. In the 1920s, thyratrons were derived from early vacuum tubes such as the UV-200, which contained a small amount of argon gas to increase its sensitivity as a radio signal detector, and the German LRS relay tube, which also contained argon gas. Gas rectifiers, which predated vacuum tubes, such as the argon-filled General Electric " Tungar bulb" and the Cooper-Hewitt mercury-pool rectifier, also provided an influence. Irving Langmuir and G. S. Meikle of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Delta Distribution
In mathematics, the Dirac delta distribution ( distribution), also known as the unit impulse, is a generalized function or distribution over the real numbers, whose value is zero everywhere except at zero, and whose integral over the entire real line is equal to one. The current understanding of the unit impulse is as a linear functional that maps every continuous function (e.g., f(x)) to its value at zero of its domain (f(0)), or as the weak limit of a sequence of bump functions (e.g., \delta(x) = \lim_ \frace^), which are zero over most of the real line, with a tall spike at the origin. Bump functions are thus sometimes called "approximate" or "nascent" delta distributions. The delta function was introduced by physicist Paul Dirac as a tool for the normalization of state vectors. It also has uses in probability theory and signal processing. Its validity was disputed until Laurent Schwartz developed the theory of distributions where it is defined as a linear form acting on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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