what is the purpose of slow wave structures used in twt amplifiers
Gyrotron


the output is taken. A gyro-TWT is an amplifier that functions analogously to a travelling wave tube (TWT). It has a slow wave structure similar to a TWT paralleling the beam, with the input microwave signal applied to the upstream end and the amplified output signal taken from the downstream end. A gyro-BWO is an oscillator that functions analogously to a backward wave oscillator (BWO). It generates oscillations traveling in an opposite direction to the electron beam, which are output at the upstream end of the
17411106
Gyrotron


tube. A gyro-twystron is an amplifier that functions analogouly to a twystron, a tube that combines a klystron and a TWT. Like a klystron it has an input cavity at the upstream end followed by buncher cavities to bunch the electrons, which are followed by a TWT type slow-wave structure which develops the amplified output signal. Like a TWT it has a wide bandwidth. The gyrotron was invented in the Soviet Union. Present makers include Communications & Power Industries (USA), Gycom (Russia), Thales
17411107
Crossed-field amplifier


characteristics (such as high peak power and efficiency) and they have similar physical appearances. However, a magnetron is an oscillator and a CFA is an amplifier (although a CFA can be driven to oscillate by application of improper low voltages as can any amplifier); a CFA's RF circuit (or slow-wave structure) is similar to that in a coupled-cavity TWT. The CFA has the useful property that when power is shut off, the input simply passes to the output with very little loss. This
34752
Traveling-wave tube


A traveling-wave tube (TWT, pronounced "twit") or traveling-wave tube amplifier (TWTA, pronounced "tweeta") is a specialized vacuum tube that is used in electronics to amplify radio frequency (RF) signals in the microwave range. The TWT belongs to a category of "linear beam" tubes, such as the klystron, in which the radio wave is amplified by absorbing power from a beam of electrons as it passes down the tube. Although there are various types of TWT, two major
13078915
Traveling-wave tube


the beam. This structure provides a helical waveguide, and hence amplification can occur via velocity modulation. Helical waveguides have very nonlinear dispersion and thus are only narrowband (but wider than klystron). A coupled-cavity TWT can achieve 60 kW output power. Operation is similar to that of a klystron, except that coupled-cavity TWTs are designed with attenuation between the slow-wave structure instead of a drift tube. The slow-wave structure gives the TWT its wide bandwidth. A free electron laser allows higher frequencies.
13078925
Vacuum tube


(usually narrow-band) RF generators and still find use in radar, microwave ovens and industrial heating. Traveling-wave tubes (TWTs) are very good amplifiers and are even used in some communications satellites. High-powered klystron amplifier tubes can provide hundreds of kilowatts in the UHF range. The cathode ray tube (CRT) is a vacuum tube used particularly for display purposes. Although there are still many televisions and computer monitors using cathode ray tubes, they are rapidly being replaced by flat panel displays whose quality has
14117114
AN/TRC-97


typically used the 1 kW klystron while the line-of-sight mode used the 1W Traveling Wave Tube (TWT). The TWT was replaced late in the 97s life by a solid-state 1W amplifier. The receiver of the TRC-97 can pick up very faint radio signals as low as -105 dBm. The modified TRC-97A (with 12 channels of added multiplex) can receive signals as low as -102 dBm. It uses tunnel diodes, which utilize quantum mechanics theory, to amplify those very low signals. The signals from
22081765
Microwave Power Module


A Microwave Power Module (MPM) is a microwave device used to amplify radio frequency signals to high power levels. It is a hybrid combination of solid-state and vacuum tube electronics, which encloses a solid-state driver amplifier (SSPA), traveling wave tube amplifier (TWTA) and electronic power conditioning (EPC) modules into a single unit. Their average output power capability falls between that of solid-state power amplifiers (SSPAs) and dedicated Traveling Wave Tube (TWT) amplifiers. They may be applied wherever
7146018
Traveling-wave tube


back to the cathode. Higher powered helix TWTs usually contain beryllium oxide ceramic as both a helix support rod and in some cases, as an electron collector for the TWT because of its special electrical, mechanical, and thermal properties. There are a number of RF amplifier tubes that operate in a similar fashion to the TWT, known collectively as velocity-modulated tubes. The best known example is the klystron. All of these tubes use the same basic "bunching" of electrons to provide the amplification process, and differ largely
13078921
Traveling-wave tube


categories are: A major advantage of the TWT over some other microwave tubes is its ability to amplify a wide range of frequencies, a wide bandwidth. The bandwidth of the helix TWT can be as high as two octaves, while the cavity versions have bandwidths of 10–20%. Operating frequencies range from 300 MHz to 50 GHz. The power gain of the tube is on the order of 40 to 70 decibels, and output power ranges from a few watts to megawatts. TWTs account for over 50% of the sales volume
13078916
Traveling-wave tube


A TWT integrated with a regulated power supply and protection circuits is referred to as a traveling-wave-tube amplifier (abbreviated TWTA and often pronounced "TWEET-uh"). It is used to produce high-power radio frequency signals. The bandwidth of a broadband TWTA can be as high as one octave, although tuned (narrowband) versions exist; operating frequencies range from 300 MHz to 50 GHz. A TWTA consists of a traveling-wave tube coupled with its protection circuits (as in klystron) and regulated
13078926
Crossed-field amplifier


This forms a thin spinning disk of electrons with a flow pattern like spinning water as it drains from a sink or toilet. A slow-wave structure is located above and below the spinning disk of electrons. Electrons flow much slower than the speed of light, and the slow wave structure reduces the velocity of the input RF enough to match the electron velocity. The RF input is introduced into the slow wave structure. The alternating microwave field causes the electrons to alternately speed up and slow down. These disturbances grow larger as
34754
Backward-wave oscillator


signal on the passing beam causes the same velocity modulation effect, but because of the direction of the RF signal and specifics of the waveguide, this modulation travels backward along the beam, instead of forward. This propagation, the "slow-wave", reaches the next hole in the folded waveguide just as the same phase of the RF signal does. This causes amplification just like the traditional TWT. The difference in the two systems is that in the TWT the speed of propagation in the helix has to be similar to
19749243
Operational amplifier


open-loop level detectors described above will be relatively slow. External overall positive feedback may be applied, but (unlike internal positive feedback that may be applied within the latter stages of a purpose-designed comparator) this markedly affects the accuracy of the zero-crossing detection point. Using a general-purpose op-amp, for example, the frequency of "E" for the sine to square wave converter should probably be below 100 Hz. In a non-inverting amplifier, the output voltage changes in the same
3088342
Traveling-wave tube


of all microwave vacuum tubes. They are widely used as the power amplifiers and oscillators in radar systems, communication satellite and spacecraft transmitters, and electronic warfare systems. The TWT is an elongated vacuum tube with an electron gun (a heated cathode that emits electrons) at one end. A voltage applied across the cathode and anode accelerates the electrons towards the far end of the tube, and an external magnetic field around the tube focuses the electrons into a beam. At the other end of the tube the electrons strike the "
13078917
Traveling-wave tube


RF signals to Earth stations. Syncom 2 was successfully launched into geosynchronous orbit on July 26, 1963 with two 2 W, 1850 MHz Hughes-designed TWT transponders — one active and one spare. TWTAs are commonly used as amplifiers in satellite transponders, where the input signal is very weak and the output needs to be high power. A TWTA whose output drives an antenna is a type of transmitter. TWTA transmitters are used extensively in radar, particularly in airborne fire-control radar systems, and in electronic warfare and self
13078932
Microwave


the electromagnetic waves becomes small in comparison to the size of the structures used to process them, microwave techniques become inadequate, and the methods of optics are used. High-power microwave sources use specialized vacuum tubes to generate microwaves. These devices operate on different principles from low-frequency vacuum tubes, using the ballistic motion of electrons in a vacuum under the influence of controlling electric or magnetic fields, and include the magnetron (used in microwave ovens), klystron, traveling-wave tube (TWT), and gyrotron.
2990
L3 Electron Devices


Electron Devices (formerly Electron Dynamics Division (EDD), was a division of the Industrial Electronics Group of the Hughes Aircraft Company) is a technology company specializing in the manufacture of microwave devices for ground-based, airborne and satellite communications and radar. EDD began operations at their Torrance, California, facility in 1967. They are known for their traveling-wave tubes (TWTs), traveling-wave tube amplifiers (TWTAs), microwave power modules (MPMs) and electronic power conditioners (EPCs) as well as xenon
21730235
Traveling-wave tube


, the drift tube must often be several feet long. In comparison, in the TWT the acceleration is caused by the interactions with the helix along the entire length of the tube. This allows the TWT to have a very low noise output, a major advantage of the design. More usefully, this process is much less sensitive to the physical arrangement of the tube, which allows the TWT to operate over a wider variety of frequencies. TWT's are generally at an advantage when low noise and frequency variability are useful.
13078923
Nike-X


set on the northeast side that was never used. A tall clutter fence surrounded the building, preventing reflections from nearby mountains. Groundbreaking on the MAR-I site started in March 1963 and construction proceeded rapidly. The radar was powered up for the first time in June 1964 and achieved its first successful tracking on 11 September 1964, repeatedly tracking and breaking lock on a balloon target over a 50-minute period. However, the system demonstrated very low reliability in the transmitter's travelling wave tube (TWT) amplifiers, which led to
2594684
Traveling-wave tube


beam down the center of the helix instead of outside of it. These configuration changes resulted in much greater wave amplification than Haeff's design as they relied on the physical principles of velocity modulation and electron bunching. Kompfner developed his TWT in a British Admiralty radar laboratory during World War II. His first sketch of his TWT is dated November 12, 1942, and he built his first TWT in early 1943. The TWT was later refined by Kompfner, John R. Pierce, and Lester M. Field at Bell Labs. Note that
13078930
Traveling-wave tube


this combination is called a linearized TWTA (LTWTA, "EL-tweet-uh"). Broadband TWTAs generally use a helix TWT and achieve less than 2.5 kW output power. TWTAs using a coupled cavity TWT can achieve 15 kW output power, but at the expense of narrower bandwidth. The original design and prototype of the TWT was done by Andrei "Andy" Haeff c. 1931 while he was working as a doctoral student at the Kellogg Radiation Laboratory at Caltech. His original patent, "Device for and Method of
13078928
Traveling-wave tube


Kompfner's US patent, granted in 1953, does cite Haeff's previous work. By the 1950s, after further development at the Electron Tube Laboratory at Hughes Aircraft Company in Culver City, California, TWTs went into production there, and by the 1960s TWTs were also produced by such companies as the English Electric Valve Company, followed by Ferranti in the 1970s. On July 10, 1962, the first communications satellite, Telstar 1, was launched with a 2 W, 4 GHz RCA-designed TWT transponder used for transmitting
13078931
Cavity magnetron


as a klystron or a traveling-wave tube (TWT), the magnetron cannot function as an amplifier in order to increase the intensity of an applied microwave signal; the magnetron serves solely as an oscillator, generating a microwave signal from direct current electricity supplied to the vacuum tube. An early form of magnetron was invented by H. Gerdien in 1910. Another form of magnetron tube, the split-anode magnetron, was invented by Albert Hull of General Electric Research Laboratory in 1920, but it achieved only a frequency of
789641
Terahertz metamaterial


not available. This results in a region that is underutilized, and the lack of novel amplifiers can be directly attributed as one of the causes. Research work has involved investigating, creating, and designing light-weight slow-wave vacuum electronics devices based on traveling wave tube amplifiers. These are designs that involve folded waveguide, slow-wave circuits, in which the terahertz wave meanders through a serpentine path while interacting with a linear electron beam. Designs of folded-waveguide traveling-wave tubes are at frequencies of 670,
12847898
Microwave Power Module


requirements are typically low-voltage DC (28 - 270V DC). A microwave power module consists of a solid state power amplifier, which drives a vacuum power booster, typically a traveling wave tube. The high voltage power supply required by the TWT is provided by an electronic power conditioner. In pulsed-mode MPMs, the power conditioner provides a pulsed high voltage that is triggered by a trigger input. MPMs also include a microcontroller, which is responsible for controlling the operation of the module, such as making sure the
7146021
SAR-Lupe


are planned to be launched on Falcon 9 sometime in 2019 and 2020. • Global observation coverage capability • Use of a parabolic SAR reflector antenna of size: 3.3 m x 2.7 m. The choice of using a single beam offset reflector antenna instead of an active beam-steering antenna represented a major cost saving in the development of the instrument. SAR-Lupe uses a single beam offset reflector antenna and a TWT (Travelling Wave Tube) based transmitter, illuminated by a feed horn on a deployable boom. The highly efficient TWT
17467945
Power dividers and directional couplers


not shown in the diagrams for simplicity. Applying in-phase power to both input ports would not get the desired result: the quadrature sum of the two inputs would appear at both output ports – that is half the total power out of each. This approach allows the use of numerous less expensive and lower-power amplifiers in the circuitry instead of a single high-power TWT. Yet another approach is to have each solid state amplifier (SSA) feed an antenna and let the power be combined in space or be
16157691
Traveling-wave tube


Controlling High Frequency Currents", was filed in 1933 and granted in 1936. The invention of the TWT is often attributed to Rudolf Kompfner in 1942–1943. In addition, Nils Lindenblad, working at RCA (Radio Corporation of America) in the USA also filed a patent for a device in May 1940 that was remarkably similar to Kompfner's TWT. Both of these devices were improvements over Haeff's original design as they both used the then newly invented precision electron gun as the source of the electron beam and they both directed the
13078929
Microchannel plate detector


MCPs, low voltage and instead more sensitive and fast semiconductor amplifiers after the anode. (see: Secondary emission#Special amplifying tubes, With high count rates or slow detectors (MCPs with phosphor screen or discrete photomultipliers) pulses overlap. In this case a high impedance (slow, but less noisy) amplifier and an ADC is used. Since the output signal from the MCP is generally small, the presence of the thermal noise limits the measurement of the time structure of the MCP signal. However, with fast amplification schemes it is
9208446
Korg Wavestation


samples and single-cycle waveforms or a wave sequence to an oscillator. Each oscillator has its own digital filter, amplifier, amp envelope, general purpose envelope, two LFOs, and numerous modulation routings. The mix envelope for vector synthesis is also found at the Patch level. There are 35 Patches per Bank. Wave Sequences are at the bottom tier of the Wavestation's programming structure. The Wavestation treats these as if they are discrete PCM waveforms when assigning them to oscillators in a Patch, although a wave sequence itself is
4662634
Traveling-wave tube


Helix TWTs are limited in peak RF power by the current handling (and therefore thickness) of the helix wire. As power level increases, the wire can overheat and cause the helix geometry to warp. Wire thickness can be increased to improve matters, but if the wire is too thick it becomes impossible to obtain the required helix pitch for proper operation. Typically helix TWTs achieve less than 2.5 kW output power. The coupled-cavity TWT overcomes this limit by replacing the helix with a series of coupled cavities arranged axially along
13078924
Microwave


cells in microwave hyperthermy. The traveling wave tube (TWT) developed in 1943 by Rudolph Kompfner and John Pierce provided a high-power tunable source of microwaves up to 50 GHz, and became the most widely used microwave tube (besides the ubiquitous magnetron used in microwave ovens). The gyrotron tube family developed in Russia could produce megawatts of power up into millimeter wave frequencies, and is used in industrial heating and plasma research, and to power particle accelerators and nuclear fusion reactors. The development of semiconductor electronics in the 1950s
3033
Operational amplifier applications


forced to act as a comparator. The smallest difference between the input voltages will be amplified enormously, causing the output to swing to nearly the supply voltage. However, it is usually better to use a dedicated comparator for this purpose, as its output has a higher slew rate and can reach either power supply rail. Some op-amps have clamping diodes on the input that prevent use as a comparator. The integrator is mostly used in analog computers, analog-to-digital converters and wave-shaping circuits. Integrates
17491654
Cochlear amplifier


D.T. Kemp. This was confirmation that such an active mechanism was present in the ear. These emissions are now termed otoacoustic emissions and are produced by what we call the cochlear amplifier. The first modeling effort to define the cochlear amplifier was a simple augmentation of Georg von Békésy's passive traveling wave with an active component. In such a model, a lop sided pressure about the Organ of Corti is hypothesized which actively adds to the passive traveling wave to form the active traveling wave. Perhaps the most popular example of this model
8412601
Reflection seismology


incidence. This equation reduces to that of normal incidence at formula_11=0. The time it takes for a reflection from a particular boundary to arrive at the geophone is called the "travel time". If the seismic wave velocity in the rock is known, then the travel time may be used to estimate the depth to the reflector. For a simple vertically traveling wave, the travel time formula_13 from the surface to the reflector and back is called the Two-Way Time (TWT) and is given by the formula where formula_15
10521633
AN/FPQ-16 PARCS


maintained the radar and other EPARCS subsystems (an extension was granted in 2012). Deployment of the Solid State Phased Array Radar System (SSPARS) replaced BMEWS and upgraded AN/FPS-115 PAVE PAWS with solid state power amplifiers (e.g., with a 1987 AN/FPS-120 at Thule); but for the EPARCS with "obsolete radar technology" in 1994 and for Cobra Dane in Alaska, L-3 Communications was contracted to supply 2004-9 TWTs. Late in the 2000s decade the USAF began upgrading SSPARS to use Boeing AN/
13620915
Amplifier


of power to achieve very high gain, maintaining a good noise figure at the same time. Video amplifiers are designed to process video signals and have varying bandwidths depending on whether the video signal is for SDTV, EDTV, HDTV 720p or 1080i/p etc.. The specification of the bandwidth itself depends on what kind of filter is used—and at which point ( or for example) the bandwidth is measured. Certain requirements for step response and overshoot are necessary for an acceptable TV image. Traveling wave tube amplifiers (TWTAs
9903510
Dummy load


A dummy load is a device used to simulate an electrical load, usually for testing purposes. In radio a dummy antenna is connected to the output of a radio transmitter and electrically simulates an antenna, to allow the transmitter to be adjusted and tested without radiating radio waves. In audio systems a dummy load is connected to the output of an amplifier to electrically simulate a loudspeaker, allowing the amplifier to be tested without producing sound. Load banks are connected to electrical power supplies to simulate the supply's intended electrical load for testing
14432006
Rayleigh wave


can travel faster than the shorter wavelength (high frequency) waves. Rayleigh waves thus often appear spread out on seismograms recorded at distant earthquake recording stations. It is also possible to observe Rayleigh wave dispersion in thin films or multi-layered structures. Rayleigh waves are widely used for materials characterization, to discover the mechanical and structural properties of the object being tested – like the presence of cracking, and the related shear modulus. This is in common with other types of surface waves. The Rayleigh waves used for this purpose are
17575372
Pioneer 6, 7, 8, and 9


"Voyager 2" on August 13, 2012. It is also believed that contact is still possible with "Pioneer 7" and "8"; only "Pioneer 9" is definitely not working. December 16, 1965 Launched at 07:31:00 UTC from Cape Canaveral to a circular solar orbit with a mean distance of 0.8 AU. December 1995 The prime Traveling-wave tube (TWT) failed some time after December 1995. July 1996 Spacecraft commanded to the backup TWT. October 6, 1997 Tracked with the 70 meter Deep
9199945
Earth Microbiome Project


a metagenomic sample using two main approaches. If the biological question to be resolved is, what types of organisms are present and in what abundance, the preferred approach would be to target and amplify a specific gene that is highly conserved among the species of interest. The 16S ribosomal RNA gene for bacteria and the 18S ribosomal RNA gene for protists are often used as target genes for this purpose. The advantage of targeting a specific gene is that the gene can be amplified and sequenced at a very high coverage. This approach is
7017263
Electroencephalography


frequencies. Unfortunately there is no agreement in standard reference works on what these ranges should be – values for the upper end of alpha and lower end of beta include 12, 13, 14 and 15. If the threshold is taken as 14 Hz, then the slowest beta wave has about the same duration as the longest spike (70 ms), which makes this the most useful value. Others sometimes divide the bands into sub-bands for the purposes of data analysis. "Ultra-slow" or "near-
10038914
Backward-wave oscillator


the beam. This is normally accomplished by drilling a hole through a rectangular waveguide and shooting the beam through the hole. The waveguide then goes through two right angle turns, forming a C-shape and crossing the beam again. This basic pattern is repeated along the length of the tube so the waveguide passes across the beam several times, forming a series of S-shapes. The original RF signal enters from what would be the far end of the TWT, where the energy would be extracted. The effect of the
19749242
1985 Mexico City earthquake


vibrate at the same frequency. This is the same "pitch" as a number of shallow earthquake waves. This resonance amplifies the effects of the shock waves coming from an earthquake far away. However, only certain types of structures are vulnerable to this resonance effect. Taller buildings have their own frequencies of vibration. Those that are six to fifteen stories tall also vibrate at the 2.5-second cycle, making them act like tuning forks in the event of an earthquake. The low-frequency waves of an earthquake are amplified by the
15363443
Tehillim (Reich)


playing small tuned tambourines without jingles, clapping, maracas, marimba, vibraphone and crotales), two electronic organs, two violins, viola, cello and bass. The voices, winds and strings are amplified in performance. There is also a version for orchestra using full strings and winds, with only the voices amplified. The first and longest movement is based on canons, while the second, performed without pause, utilizes a theme and variations structure. The third movement, the only slow movement, features call-and-
5756665
Op amp integrator


The operational amplifier integrator is an electronic integration circuit. Based on the operational amplifier (op-amp), it performs the mathematical operation of integration with respect to time; that is, its output voltage is proportional to the input voltage integrated over time. The integrator circuit is mostly used in analog computers, analog-to-digital converters and wave-shaping circuits. A common wave-shaping use is as a charge amplifier and they are usually constructed using an operational amplifier though they can use high gain discrete transistor configurations
13098591
Leaky wave antenna


Leaky-Wave Antenna (LWA) belong to the more general class of Traveling wave antenna, that use a traveling wave on a guiding structure as the main radiating mechanism. Traveling-wave antenna fall into two general categories, slow-wave antennas and fast-wave antennas, which are usually referred to as leaky-wave antennas. The traveling wave on a Leaky-Wave Antenna is a fast wave, with a phase velocity greater than the speed of light. This type of wave radiates continuously along its length, and
6284025
Leaky wave antenna


, uniform and periodic, depending on the type of guiding structure. A uniform structure has a cross section that is uniform (constant) along the length of the structure, usually in the form of a waveguide that has been partially opened to allow radiation to occur. The guided wave on the uniform structure is a fast wave, and thus radiates as it propagates. A periodic leaky-wave antenna structure is one that consists of a uniform structure that supports a slow (non radiating) wave that has been periodically modulated in
6284027
TRS-80


4, and later systems. The Model I has no built-in speaker. Square wave tones can be produced by outputting data to the cassette port and plugging an amplifier into the cassette "Mic" line. Most games use this ability for sound effects. An adapter was available to use Atari joysticks. User data was originally stored on cassette tape. RadioShack's model CTR-41 cassette recorder was included with the US$599 package. The software-based cassette tape interface is slow and erratic; Green described it as "crummy
12113066
Weberian apparatus


, the os suspensorium and the third rib that interact directly with the anterior chamber of the swim bladder. The Weberian apparatus functions by transmitting auditory signals straight from the gas bladder, through the Weberian ossicles and then straight into the labyrinth structures of the inner ear. The structure essentially acts as an amplifier of sound waves that would otherwise be only slightly perceivable by the inner ear structure alone. With the added function of the swim bladder as a resonating chamber, signals are amplified to noticeable levels. Embryonic analysis of Weberian apparatuses of
15540513
Backward-wave oscillator


A backward wave oscillator (BWO), also called carcinotron (a trade name for tubes manufactured by CSF, now Thales) or backward wave tube, is a vacuum tube that is used to generate microwaves up to the terahertz range. Belonging to the traveling-wave tube family, it is an oscillator with a wide electronic tuning range. An electron gun generates an electron beam that interacts with a slow-wave structure. It sustains the oscillations by propagating a traveling wave backwards against the beam. The generated electromagnetic wave power
19749234
Leaky wave antenna


some fashion. Since a slow wave radiates at discontinuities, the periodic modulations (discontinuities) cause the wave to radiate continuously along the length of the structure. From a more sophisticated point of view, the periodic modulation creates a guided wave that consists of an infinite number of space harmonics (Floquet modes). Although the main ("n" = 0) space harmonic is a slow wave, one of the space harmonics (usually the "n" = −1) is designed to be a fast wave, and this
6284028
Unihemispheric slow-wave sleep


. In other words, the usage of USWS of certain species of birds increases as the risk of predation increases. The evolution of both cetaceans and birds may have involved some mechanisms for the purpose of increasing the likelihood of avoiding predators. Certain species, especially of birds, that acquired the ability to perform unihemispheric slow-wave sleep had an advantage and were more likely to escape their potential predators over other species that lacked the ability. Birds can sleep more efficiently with both hemispheres sleeping simultaneously (bihemispheric slow wave sleep) when
21121815
Personal sound amplification product


ear(s) of the user. The main components are a microphone, amplifier, speaker, volume controller and power source. The microphone captures the sound (pressure) waves and converts them to an electric signal. The amplifier (an electronic circuit) increases the amplitude of the electric signal using a power source (battery). The speaker converts the amplified electric signal back into a sound wave. The volume (gain) control is used to adjust the amount of amplification applied to the electric signal and thus, indirectly, controls
8655865
Constant-voltage speaker system


amplifier: A general-purpose amplifier with typical low-impedance output is used. Its output is connected to the primary of an external step-up transformer. Special-purpose transformers can tailor the system design to the project's target power levels. Multiple amplifiers can be combined together via transformers to yield higher voltage and higher current capacity lines. For instance, three 70-volt amplifiers have been used to make a 210-volt line by connecting them to a special-purpose external output transformer that has three primaries and a single secondary.
18064923
Valve audio amplifier


and other applications) have different purposes from those of hi-fi amplifiers. The purpose is not necessarily to reproduce sound as accurately as possible, but rather to fulfill the musician's concept of what the sound should be. For example, distortion is almost universally considered undesirable in hi-fi amplifiers but may be considered a desirable characteristic in performance. Small signal circuits are often deliberately designed to have very high gain, driving the signal far outside the linear range of the tube circuit, to deliberately generate large amounts of harmonic
2105763
Megaphone


public address system, an electronic device that amplifies the human voice like an acoustic megaphone, using electric power. It consists of a microphone to convert sound waves into an electrical audio signal, an amplifier powered by a battery to increase the power of the audio signal, and a loudspeaker to convert the audio signal to sound waves again. Although slightly heavier than acoustic megaphones, electric megaphones can amplify the voice to a higher level, to over 90 dB. They have replaced acoustic megaphones in most applications, and are generally used to
1412008
Magnetic amplifier


the magnetic amplifiers. They were used for the master stable element systems, for slow moving transmission for controlling guns, directors and rangefinders and train and elevation controls. Magnetic amplifiers were used in aircraft systems (avionics) before the advent of high reliability semiconductors. They were important in implementing early autoland systems and Concorde made use of the technology for the control of its engine air intakes before development of a system using digital electronics. Magnetic amplifiers were used in stabilizer controls of V2 rockets. Magnetic amplifiers were widely studied during the 1950s
9943705
Quantum noise


which is reproduced at the output. In a narrow sense, the optical quantum amplifier reproduces both amplitude and phase of the input wave. Usually, the amplifier amplifies many modes of the optical field; special efforts are required to reduce the number of these modes. In the idealized case, one may consider just one mode of the electromagnetic field, which corresponds to a pulse with definite polarization, definite transversal structure and definite arrival time, duration and frequency, with uncertainties limited by the Heisenberg uncertainty principle. The input mode may
11093528
Photonics


Optical amplifiers used in optical communications are erbium-doped fiber amplifiers, semiconductor optical amplifiers, Raman amplifiers and optical parametric amplifiers. A very advanced research topic on optical amplifiers is the research on quantum dot semiconductor optical amplifiers. Photodetectors detect light. Photodetectors range from very fast photodiodes for communications applications over medium speed charge coupled devices (CCDs) for digital cameras to very slow solar cells that are used for energy harvesting from sunlight. There are also many other photodetectors based on thermal, chemical, quantum, photoelectric and other effects.
14574907
Advanced Extremely High Frequency


be time-shared to cover up to 24 targets. The two high resolution coverage area antennas enable operations in the presence of in-beam jamming; the nulling antennas are part of the electronic defense that helps discriminate true signals from electronic attack. Another change from existing satellites is using solid-state transmitters rather than the traveling wave tubes used in most high-power military SHF/EHF applications. TWTs have a fixed power output; the newer devices allow varying the transmitted power, both for lowering the probability of intercept and
7956668
Optical amplifier


can distinguish between more suitable for energy of average power scaling. Beside their use in fundamental research from gravitational wave detection to high energy physics at NIF they can also be found in many today’s ultra short pulsed lasers. Doped fiber amplifiers (DFAs) are optical amplifiers that use a doped optical fiber as a gain medium to amplify an optical signal. They are related to fiber lasers. The signal to be amplified and a pump laser are multiplexed into the doped fiber, and the signal is amplified through interaction with the doping
19097148
Amplifier


-tube amplifiers (also known as tube amplifiers or valve amplifiers) use a vacuum tube as the active device. While semiconductor amplifiers have largely displaced valve amplifiers for low-power applications, valve amplifiers can be much more cost effective in high power applications such as radar, countermeasures equipment, and communications equipment. Many microwave amplifiers are specially designed valve amplifiers, such as the klystron, gyrotron, traveling wave tube, and crossed-field amplifier, and these microwave valves provide much greater single-device power output at microwave frequencies
9903502
MEASAT Satellite Systems


and testing of equipment for a satellite control station on Langkawi Island, and training of Malaysian spacecraft controllers. MEASAT 1 had five high-power transponders in Ku band for the direct-to-user service, powered by 112-watt traveling-wave tube amplifiers. The regional service to Malaysia was provided on 12 transponders in C band, using 12-watt solid state amplifiers. MEASAT-2 had 11 active transponders in Ku band. Eight of these use 95-watt traveling-wave amplifiers, and three have 62 watts. MEASAT-2 also had six active transponders
16017143
Pressure measurement


one side of the U-tube and has a scale beside the narrower column. The column may be inclined to further amplify the liquid movement. Based on the use and structure, following types of manometers are used A McLeod gauge isolates a sample of gas and compresses it in a modified mercury manometer until the pressure is a few millimetres of mercury. The technique is very slow and unsuited to continual monitoring, but is capable of good accuracy. Unlike other manometer gauges, the McLeod gauge reading is dependent on the composition of
20483572
Multi-purpose reef


Bargara, Queensland participated in an effort to improve the quality of a surfing wave on a natural reef. While not a structure in and of itself, the effort consisted of shifting boulders which caused the wave to break irregularly and at time dangerously over shallow rock. Work was completed using heavy equipment to move the offending rocks during the low tide when the rocks were exposed. The first structure built specifically for the improvement of surfing was the Cable Station Reef constructed in 1999 in Perth, Western Australia. This structure was built from
16309267
Temperature coefficient


electrical resistivity will decrease with increasing temperature. Materials with a negative temperature coefficient have been used in floor heating since 1971. The negative temperature coefficient avoids excessive local heating beneath carpets, bean bag chairs, mattresses, etc., which can damage wooden floors, and may infrequently cause fires. Residual magnetic flux density or Br changes with temperature and it is one of the important characteristics of magnet performance. Some applications, such as inertial gyroscopes and traveling-wave tubes (TWTs), need to have constant field over a wide
10192208
History of radar


long-range Perimeter Acquisition Radar (PAR) and a shorter-range, more precise Missile Site Radar (MSR). The PAR was housed in a -high nuclear-hardened building with one face sloping 25 degrees facing north. This contained 6,888 antenna elements separated in transmitting and receiving phased arrays. The L-Band transmitter used 128 long-life traveling-wave tubes (TWTs), having a combined power in the megawatt range The PAR could detect incoming missiles outside the atmosphere at distances up to . The MSR had
8820026
MIQE


the length of the sequence being amplified, information about the specificity screen used such as BLAST, what splicing variants exist for the sequence, and where the exon or intron for each primer is. There are several desired, but not required information pieces for this section, such as the location of the amplicon, whether any pseudogenes or homologs exist, whether a sequence alignment was done and the data obtained from it, and any data on the secondary structure of the amplified sequence. Creation of the oligonucleotides requires only two pieces of
16723658
Valve RF amplifier


use a single relatively simple tuned network. Thus while solid state high power short wave transmitters are technically possible, economic considerations still favor valves above 3 MHz and 10,000 watts. Amateurs also use valve amplifiers in the 500-1500 watt range mainly for economic reasons. Valve audio amplifiers typically amplify the entire audio range between 20 Hz and 20 kHz or higher. They use an iron core transformer to provide a suitable high impedance load to the valve(s) while driving a speaker, which is typically 8 Ohms. Audio amplifiers normally use
19813317
Goubau line


bend inwards towards the conductor, which keeps the waves entrained. Bends of large radius are tolerated, but too sharp a bend in the single wire will cause the line to radiate and lose energy into space. In theory the dielectric coating is a requirement, it slows the wave and focuses it along the wire. But some users note that in practice the finite conductivity of metals may produce a similar effect, and a bare G-line can entrain a propagating wave. Other structures besides horns have been used to couple radio
16038792
Instrument amplifier


lacquered beige-light brown fabric covering used on these amplifiers. The smallest "combo" amplifiers, which are mainly used for individual practice and warm-up purposes, may have only a single 8" or 10" speaker. Some harmonica players use these small combo amplifiers for concert performances, though, because it is easier to create natural overdrive with these lower-powered amplifiers. Larger combo amplifiers, with one 12 inch speaker or two or four 10 or 12 inch speakers are used for club performances and larger venues.
14303519
Afar Triple Junction


crustal extension and gives a model of pre-rifting crustal connection. Seismic tomography compiles P-wave and S-wave data from movements within the earth to create a 3D velocity model of the Earth's subsurface. The models distinguish between fast velocity, high anomaly, and slow velocity, slow anomaly, time measurements. Multiple tomography models show a slow anomaly structure beneath southern Africa. Grand, S. (1997) models the large anomaly to extend from the base of the mantle to approximately 1000 km depth. This slow anomaly
16185078
Optical parametric amplifier


the capacitance of a varactor diode). The result is that some of the energy of the local oscillator gets transferred to the signal frequency "f", as well as the difference ("idler") frequency "f"-"f". The term "parametric" amplifier is used because the "parameters" of the circuit are varied. The optical case uses the same basic principle--transferring energy from a wave at the pump frequency to waves at the signal and idler frequencies--so it took the same name. 1.
7905375
Crossed-field amplifier


A crossed-field amplifier (CFA) is a specialized vacuum tube, first introduced in the mid-1950s and frequently used as a microwave amplifier in very-high-power transmitters. Raytheon engineer William C. Brown's work to adapt magnetron principles to create a new broadband amplifier is generally recognized as the first CFA, which he called an Amplitron. Other names that are sometimes used by CFA manufacturers include Platinotron or Stabilotron. A CFA has lower gain and bandwidth than other microwave amplifier tubes (such as klystrons or traveling-wave tubes
34750
Shear wave splitting


Hess observed, from previous seismic velocity experiments with olivine crystals, that if the crystals had even a slight statistical orientation this would be extremely evident in the seismic velocities recorded using seismic refraction. This concept was tested using seismic refraction profiles from the Mendocino Fracture Zone. Hess found that the slow shear waves propagated perpendicular to the plane of slip and the higher velocity component was parallel to it. He inferred that the structure of oceanic basins could be recorded quickly and understood better if these techniques were used. Ando (1980) focused
9864517
Active pixel sensor


a simple switch in the pixel to read out the photodiode integrated charge. Pixels were arrayed in a two-dimensional structure, with an access enable wire shared by pixels in the same row, and output wire shared by column. At the end of each column was an amplifier. Passive-pixel sensors suffered from many limitations, such as high noise, slow readout, and lack of scalability. The addition of an amplifier to each pixel addressed these problems, and resulted in the creation of the active-pixel sensor.
21123457
Blast shelter


in civil defense. There are above-ground, below-ground, dedicated, dual-purpose, and potential blast shelters. Dedicated blast shelters are built specifically for the purpose of blast protection (see bunker). Dual-purpose blast shelters are existing structures with blast-protective properties that have been modified to accommodate people seeking protection from blasts. Potential blast shelters are existing structures or geological features exhibiting blast-protective properties that have potential to be used for protection from blasts. Blast shelters deflect the blast wave from nearby
6567858
Narayanan Komerath


the asteroid belts using electromagnetic waves and assemble them into radiation shields and structures where humans could live, among other purposes. The idea came to Komerath by analogy with the technique of "acoustic shaping", where sound waves can accurately position small objects such as beads into larger solid objects within a weightless environment. In space, radio waves would take the place of sound waves. Although huge amounts of energy would be needed, solar power could be used and the approach would avoid the requirement to transport material from Earth. Komerath
10464178
Operational amplifier applications


by the feedback loop in the same way as the non-inverting amplifier, with "B"=1. A summing amplifier sums several (weighted) voltages: Combines very high input impedance, high common-mode rejection, low DC offset, and other properties used in making very accurate, low-noise measurements Produces a very low distortion sine wave. Uses negative temperature compensation in the form of a light bulb or diode. Operational amplifiers can be used in construction of active filters, providing high-pass, low-pass,
17491652
Power amplifier classes


class AB with just the 80 v supplies in place of the 40 v supplies, the T1 and T3 transistors would need to be in conduction throughout the 0v to 80 v signal with the corresponding VI losses all through the vout wave period - not just the brief high energy bursts. To achieve this rail tracking control, T2 and T4 act as current amplifiers, each in series with its low voltage counterpart T1 and T3. The purpose of T2 and T3 is to allow back-biasing diode D2 when vout is at a
5236452
TDRS-1


. Along with Marisat F2, GOES 3 and LES-9, it was one of a number of satellites that were transferred to the US National Science Foundation for communications with the Amundsen-Scott South Pole Station. After Marisat was retired, TDRS-1 became the primary means of communication with the research station. The last functioning traveling-wave tube amplifier aboard TDRS-1 failed in October 2009, rendering the spacecraft unusable for communications purposes. The craft was moved into a decommissioning orbit beginning on or about October 21, 2009. Decommissioning was started on
11667478
Weberian apparatus


system, specifically the inner ear, to the swim bladder. The structure acts as an amplifier of sound waves that would otherwise be only slightly perceivable by the inner ear structure alone. The generalized structure of the Weberian apparatus is akin to a skeletal complex of bones and ossicles that are physically connected to the labyrinth auditory complex anteriorly and the anteriormost region of the swim bladder posteriorly. The entire structure is derived from skeletal elements of the first four vertebrae. The involved elements include: the supraneural bones of the skull; modified neural
15540511
Valve RF amplifier


noise figures substantially lower than tubes at UHF. Thus, the tuners of television sets were among the first parts of consumer electronics were transistors were used. Semiconductor amplifiers have overwhelmingly displaced valve amplifiers for low and medium power applications at all frequencies. Valves continue to be used in some high-power, high-frequency amplifiers used for short wave broadcasting, VHF and UHF TV and (VHF) FM radio, also in existing "radar, countermeasures equipment, or communications equipment" (p. 56, Symons .. a reference now
19813349
Bose–Einstein condensate


slowed a beam of light to about 17 meters per second using a superfluid. Hau and her associates have since made a group of condensate atoms recoil from a light pulse such that they recorded the light's phase and amplitude, recovered by a second nearby condensate, in what they term "slow-light-mediated atomic matter-wave amplification" using Bose–Einstein condensates: details are discussed in "Nature". Another current research interest is the creation of Bose–Einstein condensates in microgravity in order to use its properties
4192591
Direct-field acoustic testing


Direct-field acoustic testing, or DFAT, is a technique used for acoustic testing of aerospace structures by subjecting them to sound waves created by an array of acoustic drivers. The method uses electro-dynamic acoustic speakers, arranged around the test article to provide a uniform, well-controlled, direct sound field at the surface of the unit under test. The system employs high capability acoustic drivers, powerful audio amplifiers, a narrow-band multiple-input-multiple-output (MIMO) controller and precision laboratory microphones to
1583580
Lecher line


tetrode (QQV03-20) 432 MHz amplifier described by G.R Jessop uses a Lecher line anode tank. Quarter-wave Lecher lines are used for the tuned circuits in the RF amplifier and local oscillator portions of modern television sets. The tuning necessary to select different stations is done by varactor diodes across the Lecher line. The separation between the Lecher bars does not affect the position of the standing waves on the line, but it does determine the characteristic impedance, which can be important for matching the line to the source of
5811148
Bulkhead (barrier)


develop bulkheads in an attempt to slow large landslide erosion caused by wave action. Studies over recent decades have resulted in public awareness as to potential negative effects that bulkheads may bring to beaches and the interconnected habitat areas of fish, plants, and birds. Many states have enacted laws to protect beaches to allow for future use of the beaches, as well as protect these natural habitats. While bulkheads may serve their purpose to slow erosion at a bluff or beachfront, they commonly cause a domino effect of change to the beach profile
9322149
Leaky wave antenna


Unlike the slow-wave structure, a very narrow beam can be created at any angle by choosing a sufficiently small value of α. A simple formula for the beam width, measured between half-power points (formula_4), is: formula_5 where L is the length of the leaky-wave antenna, and Δθ is expressed in radians. For 90% of the power radiated it can be assumed: formula_6 Since leakage occurs over the length of the slit in the waveguiding structure, the whole length constitutes the antenna's
6284032
Music technology (electric)


coating on it. Analog sound reproduction is the reverse process, with a bigger loudspeaker diaphragm causing changes to atmospheric pressure to form acoustic sound waves. Electrically generated signals may also be recorded directly from devices such as an electric guitar pickup, without the use of acoustic sounds or amplifiers in the recording process (other than the need for musicians to hear herself playing during recording session). The first device that could record actual sounds as they passed through the air (but could not play them back—the purpose was only visual
17587704
Multi-purpose reef


A multi-purpose reef, also commonly known as an artificial surfing reef or surf reef, is a structure located offshore designed to induce wave breaking in a manner that creates a wave suitable for surfing or body boarding. Artificial surfing reefs can exist in many different configurations and be built from a variety of different materials. To date there have been fewer than ten attempts to build such a structure worldwide. Artificial surfing reefs are a variation of a long existing type of coastal structure known as a submerged breakwater. Submerged breakwaters have
16309264
Valve RF amplifier


, class C amplifiers normally use a high Q output network which removes the harmonics, leaving an undistorted sine wave identical to the input waveform. Class C is suitable only for amplifying signals with a constant amplitude, such as FM, FSK, and some CW (Morse code) signals. Where the amplitude of the input signal to the amplifier varies as with single-sideband modulation, amplitude modulation, video and complex digital signals, the amplifier must operate class A or AB, to preserve the envelope of the driving signal in
19813320
Polarizer


-handed, clockwise circularly polarized light one simply rotates the axis of the quarter-wave plate 90° relative to the linear polarizer. This reverses the fast and slow axes of the wave plate relative to the transmission axis of the linear polarizer reversing which component leads and which component lags. In trying to appreciate how the quarter-wave plate transforms the linearly polarized light, it is important to realize that the two components discussed are not entities in and of themselves but are merely mental constructs one uses to help appreciate what is
16734175
Cochlear amplifier


. Active compression waves were proposed as early as 1980 by P.J. Wilson due to older experimental data. However, they were widely disregarded by the research community until stronger experimental proof confirming these early experiments against the active traveling wave was produced. Thirty years after Kemp's experimental proof of the existence of Gold's cochlear amplifier and sixty years after the proposal of Gold's cochlear amplifier, the active-compression-wave cochlear amplifier was defined by M.R. Flax and W.H. Holmes. In this model the active pressure is equal on both sides
8412603
Plane wave expansion method


This corresponds to eigen modes solutions using iterative techniques, as opposed to diagonalization of the entire matrix. The PWEM is highly efficient for calculating modes in periodic dielectric structures. Being a Fourier space method, it suffers from the Gibbs phenomenon and slow convergence in some configuration when fast Fourier factorization is not used. It is the method of choice for calculating the band structure of photonic crystals. It is not easy to understand at first, but it is easy to implement. Sometimes spurious modes appear. Large problems scaled as "O(n
8390365
Optical amplifier


Both of these bands can be amplified by EDFAs, but it is normal to use two different amplifiers, each optimized for one of the bands. The principal difference between C- and L-band amplifiers is that a longer length of doped fiber is used in L-band amplifiers. The longer length of fiber allows a lower inversion level to be used, thereby giving at longer wavelengths (due to the band-structure of Erbium in silica) while still providing a useful amount of gain. EDFAs have two commonly used pumping
19097167
Slow light


a function of optical frequency, i.e. they modify the temporal component of a propagating wave. This is done by using a nonlinear effect to modify the dipole response of a medium to a signal or "probe" field. Waveguide dispersion mechanisms such as photonic crystals, coupled resonator optical waveguides (CROW), and other micro-resonator structures modify the spatial component (k-vector) of a propagating wave. Slowlight can also be achieved by exploiting the dispersion properties of planar waveguides realized with single negative metamaterials (SNM) or
2474902
Parametric oscillator


Another important example is the optical parametric oscillator, which converts an input laser light wave into two output waves of lower frequency (formula_3). When operated at pump levels below oscillation, the parametric oscillator can amplify a signal, becoming a parametric amplifier (paramp). Varactor parametric amplifiers have been developed as low-noise amplifiers in the radio and microwave frequency range. The advantage of a parametric amplifier is that it has much lower noise than an ordinary amplifier based on a gain device like a transistor or vacuum tube. This
12687513
ALSE


received using the same antennas and the data was recorded on film for analysis on Earth. The primary purpose of this experiment was to "see" into the upper 2 kilometers of the Moon's crust in a manner somewhat analogous to using seismic waves to study the internal structure of the Moon. This was possible because very long radar wavelengths were used and because the Moon is very dry, which allowed the radar waves to penetrate much deeper into the Moon than would have been possible if water were present in lunar rocks. (
18483418