Effective input noise temperature - Effective input noise temperature In telecommunication, effective input noise temperature is the source noise temperature in a two-port network or amplifier that will result in the same output noise power, when connected to a noise-free network or amplifier, as that of the actual network or amplifier connected to a noise-free source. Note: If F is the noise figure numeric and 290 K the standard noise temperature, then the effective noise temperature is given by T n = 290(F-1). Source: from Federal Standard 1037C and from MIL-STD-188.
Glossary of telecommunications transmission terms - see the Federal Standard article for copyright-related issues, as not all parts of the source document are in the public domain. Noise ambient noise level -- antenna noise temperature -- atmospheric noise -- background noise -- blue noise -- carrier noise level -- carrier-to-noise ratio (CNR) -- carrier-to-receiver noise density (C/kT) -- channel noise level -- circuit noise level -- closed-loop noise bandwidth -- C-message weighting -- cosmic noise -- effective input noise temperature -- equipment intermodulation noise -- equivalent noise resistance -- equivalent noise temperature -- equivalent pulse code modulation noise (PCM) -- equivalent satellite link noise temperature -- feeder echo noise -- flat weighting -- FM improvement factor -- FM improvement threshold -- front-end noise temperature -- HA1-receiver weighting -- idle-channel noise -- impulse noise -- in-band noise power.
Electronic amplifier - power of a signal. It does this by taking power from a power supply and shaping the output to match the input signal. This process invariably introduces some noise and distortion into the signal, and the process cannot be 100% efficient - amplifiers will always produce some waste heat. An idealised amplifer can be said to be "a piece of wire with gain", the output is an exact replica of the input, only larger. Different designs of amplifier are used for different types of applications and signals. We can broadly divide amplifiers into three categories - small signal amplifiers, low frequency power amplifiers and RF power amplifiers. Each of these calls for a slightly different design approach, mainly because of the physical limitations of the components used to implement the amplifier,.
Electrical efficiency - is the power it delivers in the form whose production is the purpose of the entity. (Efficiency should not be confused with effectiveness; a system that wastes power in producing exactly what it is meant to, is both effective and inefficient.) Specifically, calculating such an an entity's efficiency requires knowing the (input) power going into it, and the (output) power it delivers. The output power divided by the input power is the efficiency, usually expressed as a percentage. For example, an electronic amplifier that delivers 10 Watts RMS to its load, while drawing 15 Watts of DC power from a power source is 67% efficient. (10/15 x 100% = 67%) Efficiency is an obvious consideration when we wish to design systems that can operate from batteries. For more subtle reasons, the.
List of electronics topics - 32VSB 4000 series 4VSB 555 741 7400 series 8VSB A Absolute gain Access control Acceptance pattern Access time Acoustic coupler Acquisition ADSL Adaptive communications Adder Adjacent-channel interference Alarm sensor Aliasing Alternate party Alternating current AM radio Amateur radio Ambient noise level American Radio Relay League (ARRL) AMI Ammeter Ampere Amplitude distortion Amplitude modulation Amplifier Analog Analog computer Analog decoding Analogue switch Analog to digital converter Angular misalignment loss Antenna Antenna blind cone Antenna effective area Antenna gain Antenna height above average terrain Antenna noise temperature Antenna theory aperiodic antenna aperture aperture illumination Aperture-to-medium coupling loss Apollo Guidance Computer Arithmetic and logical unit Armstrong oscillator ARRL Articulation score Astable Asynchronous communications system Asynchronous operation Asynchronous start-stop Atmospheric duct Atmospheric waveguide Attenuation Audible ringing tone Audio system measurements Automatic call distributor Automatic data.
Antenna noise temperature - Antenna noise temperature In telecommunication, antenna noise temperature is the temperature of a hypothetical resistor at the input of an ideal noise-free receiver that would generate the same output noise power per unit bandwidth as that at the antenna output at a specified frequency. Note 1: The antenna noise temperature depends on antenna coupling to all noise sources in its environment as well as on noise generated within the antenna. Note 2: The antenna noise temperature is a measure of noise whose value is equal to the actual temperature of a passive device. Source: from Federal Standard 1037C and from MIL-STD-188.
Noise figure - Noise figure In telecommunication, noise figure (NF) is the ratio of the output noise power of a device to the portion thereof attributable to thermal noise in the input termination at standard noise temperature (usually 290 K). The noise figure is thus the ratio of actual output noise to that which would remain if the device itself did not introduce noise. In heterodyne systems, output noise power includes spurious contributions from image-frequency transformation, but the portion attributable to thermal noise in the input termination at standard noise temperature includes only that which appears in the output via the principal frequency transformation of the system, and excludes that which appears via the image frequency transformation. Source: from [[Federal Standard 1037C] and from MIL-STD-188..
Renewable energy - 'powerplants' for the next 4 billion years. Some renewable sources do not emit any additional carbon dioxide and do not introduce any new risks - like nuclear waste. Since they are harnessing relatively low-intensity energy this new kind of power plant needs to be distributed over a large area. To put the phrases 'low-intensity' and 'large area' easier to understand one should image that in order to produce 1000 kWh of electricity - a typical per-month-per-capita consumption of electricity in Western countries - a house owner in cloudy Europe needs to cover 10 square meters of roof with solar panels. The disadvantage of renewables is their impact on local environments and their visibility to everybody. Some people dislike the aesthetics of wind turbines or bring up nature conservation issues when it.
Jet engine - compressed by being "crushed" up against the side. This leads to a very large cross section for the engine, as well as having the air flowing the wrong way after compression - it has to be collected up and "bent" to flow to the rear of the engine where the turbine is located. Anselm Franz of Junkers' engine division (Jumo for Junkers Motoren) addressed this problem with the introduction of the axial-flow compressor. Essentially this is a turbine in reverse. Air coming in the front of the engine is blown to the rear of the engine by a fan, where it is crushed against a set of non-rotating blades called stators. The process is nowhere near as powerful as the centrifugal compressor, so a number of these pairs of fans and.
Fuzzy control system - preferable, such as dynamic logic. But still, fuzzy logic is actually very straightforward. Antilock brakes As a first example, consider an anti-lock braking system, directed by a microcontroller chip. The microcontroller has to make decisions based on brake temperature, speed, and other variables in the system. The variable "temperature" in this system can be subdivided into a range of "states": "cold", "cool", "moderate", "warm", "hot", "very hot". The transition from one state to the next is hard to define. An arbitrary static threshold might be set to divide "warm" from "hot". Like at exactly 90 degrees, warm ends and hot begins. But this would result in a discontinuous change when the input value passed over that threshold. The transition wouldn't be smooth, as would be required in braking situations. The way.
Electronics - had been used for some time to transmit data over telegraphs and telephones, the development of electronics truly began in earnest with the advent of radio. Today, electronic devices perform a much wider variety of tasks. One way of looking at an electronic system is to divide it into the following parts: Inputs - Electrical or mechanical sensors (or transducers), which take signals (in the form of temperature, pressure, etc.) from the physical world and convert them into current/voltage signals. Signal processing circuits - These consist of electronic components connected together to manipulate, interpret and transform the signals. Outputs - Actuators or other devices (also transducers) that transform current/voltage signals back into useful physical form. Take as an example a television. Its input is a broadcast signal received by an antenna.
Bel - dB is unsafe and 150 dB causes physical damage to the human body. Windows break at about 163 dB. Jet airplanes are about 133 dBA at 33 m, or 100 dBA at 170m. Eardrums pop at 190 to 198 dB. Shock waves and sonic booms are about 200 dB at 330 m. Sounds around 200 dB can cause death to humans and are generated near bomb explosions (e.g. 23 kg of TNT detonated 3 m away). The space shuttle is around 215 dB (or about 175 dBA at 17m). Nuclear bombs are 240 dB to 258 dB (distance unknown). Even louder are earthquakes, tornados, hurricanes and volcanoes. Electronics The decibel is used rather than arithmetic ratios or percentages because when certain types of circuits, such as amplifiers and attenuators, are connected.
Thermocouple - In electronics, thermocouples are a widely used kind of temperature sensor. They are cheap, interchangeable, have standard connectors and can measure a wide range of temperatures. The main limitation is accuracy, system errors of less than 1°C can be difficult to achieve. How they work In 1822, an Estonian physician named Thomas Seebeck discovered (accidentally) that the junction between two metals generates a voltage which is a function of temperature. Thermocouples rely on this discovery, the so-called Seebeck effect. Although almost any two types of metal can be used to make a thermocouple, a number of standard types are used because they possess predictable output voltages and large temperature gradients. The diagram below shows a K-type thermocouple, which is the most popular: Standard tables show the voltage produced by thermocouples at.
Scott Base - will not be unduly brief. Its usefulness was measurably increased during the 1962-63 season by extending some huts and erecting a new garage and a second seismic hut. By the end of the 1960-61 season, HMZS Endeavour was considered unfit for further Antarctic service. Her successor is a small tanker loaned by the United States to the New Zealand Navy, also named Endeavour. She currently resupplies Scott Base, transports fuel for the United States “Deep Freeze” operations and carries out oceanography and associated studies. Planning and Operation. The Ross Dependency Research Committee formulates the New Zealand Antarctic Research Programme. The committee comprises representatives of divisions of the Departments of Scientific and Industrial Research, the Lands and Survey, the Dominion Museum, the Royal Society of New Zealand, New Zealand Universities, the Chiefs.
Software radio - changes the frequency of the signal. The phase information becoems more difficult to detect in it. Many digital encoding systems depend on phase encoding. The classic solution is to mix and digitize two channels, using a reference oscillator that produces two signals that are the same frequency. However, one of the frequency outputs lags the other by 90 degrees of a cycle. This, the two sets of samples provide the needed phase information. Another related problem is that the information about the bit-timing is lost when the frequency changes. The phase information helps recover that as well. The sampling works best if it is at a simple multiple of the protocol's symbol rate. Since the distant transmitter and the receiver are linked only by the radio, this means that the sampling.
Maser - Theodore H. Maiman . Masers are used as high precision frequency references, for example as an atomic clock. They are also used as electronic amplifiers in radio telescopes. For more information about frequency reference masers, see atomic clock. Telescopic masers use arrays of chromium atoms in an insulating aluminum oxide crystal as amplifiers, pumping the energy in at a different radio frequency. That is, they use polished strips of synthetic ruby. As the input signal comes in, a gold comb (gold is used because it cannot corrode and change shape) distributes it along the strip of polished ruby. As the radio wave moves through the crystal, it knocks electrons into different orbits. As the electrons wiggle into their new, lower orbits, closer to their atoms' nuclei, they add to the wave.
Modern Naval tactics - missile so AAW rate of fire is important. The more defensive firepower in the air the more enemy threats will be destroyed. For ASW the inner screen needs good active sonar. The threat is too serious for passive sonar as immediate targeting is needed. Checking the area around and under HVUs for submarines is called 'delousing'. If possible at least one ASW helicopter is airborne all the time, to target detected contacts as quickly as possible. Detection In modern naval combat there is the potential of a deadly strike being launched from up to 600 nm away. This is a huge area to scout. The double-edged answer to this is electronic warfare. Electronic warfare (EW) consists of three elements -- Electronic Support Measures (ESM), Electronic Counter-Measures (ECM) and Electronic Counter-Counter-Measures (ECCM)..
Johnson-Nyquist noise - Johnson-Nyquist noise Johnson-Nyquist noise (sometimes only "Nyquist noise") is the equilibrium fluctuations of the electric current inside an electrical conductor, which happen without any applied voltage, due to the random thermal motion of the charge carriers (the electrons). It is to be distinguished from Shot noise, which describes the additional current fluctuations that occur when a voltage is applied and a macroscopic current starts to flow. The strength of Nyquist noise is related to the temperature and the resistance of the conductor. See: Harry Nyquist, J. Johnson J. Johnson, "Thermal Agitation of Electricity in Conductors", Phys. Rev. 32, 97 (1928) -- the experiment H. Nyquist, "Thermal Agitation of Electric Charge in Conductors", Phys. Rev. 32, 110 (1928) -- the theory.
Effective height - Effective height In telecommunication, the term effective height has the following meanings: 1. The height of the center of radiation of an antenna above the effective ground level. 2. In low-frequency applications involving loaded or nonloaded vertical antennas, the moment of the current distribution in the vertical section divided by the input current. Note: For an antenna with symmetrical current distribution, the center of radiation is the center of distribution. For an antenna with asymmetrical current distribution, the center of radiation is the center of current moments when viewed from points near the direction of maximum radiation. Source: from Federal Standard 1037C and from MIL-STD-188.
Equivalent noise resistance - Equivalent noise resistance In telecommunication, an equivalent noise resistance is a quantitative representation in resistance units of the spectral density of a noise-voltage generator, given by R n = (Ï€W n)/(kT 0), where W n is the spectral density, k is Boltzmann's constant, T 0 is the standard noise temperature (290 K), and kT 0 = 4.00 × 10-21 watt-seconds. Note: The equivalent noise resistance in terms of the mean-square noise-generator voltage, e 2, within a frequency increment, Δf , is given by R n = e 2/(4kT 0Δf ). Source: from Federal Standard 1037C.
