|
Low-noise Block Downconverter
A low-noise block downconverter (LNB) is the receiving device mounted on satellite dishes used for satellite TV reception, which collects the radio waves from the dish and converts them to a signal which is sent through a cable to the receiver inside the building. Also called a low-noise block, low-noise converter (LNC), or even low-noise downconverter (LND),Bains, Geoff. "Getting The Most Out Of An LNB" ''What Satellite & Digital TV'' (November, 2008) pp50-51 the device is sometimes inaccurately called a ''low-noise amplifier'' (''LNA''). The LNB is a combination of low-noise amplifier, frequency mixer, local oscillator and intermediate frequency (IF) amplifier. It serves as the RF front end of the satellite receiver, receiving the microwave signal from the satellite collected by the dish, amplifying it, and downconverting the block of frequencies to a lower block of intermediate frequencies (IF). This downconversion allows the signal to be carried to the indoor satellite T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LNB Dissassembled
LNB may refer to: Sport * Liga Nacional de Baloncesto, a professional basketball league in the Dominican Republic * Liga Nacional de Básquetbol, an Argentine basketball league * Liga Nacional de Básquetbol (Paraguay), Liga Nacional de Básquetbol, a Paraguayan basketball league * Ligue Nationale de Basket, the governing body of men's basketball in France * Ligue Nationale de Basket (Switzerland), a Swiss professional basketball league Other uses * Laredo National Bank, an American commercial bank * Level of neutral buoyancy * Low-noise block downconverter * Mbalanhu dialect of the Ovambo language * National Library of Latvia (Latvian: ') {{disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LNB 1
LNB may refer to: Sport * Liga Nacional de Baloncesto, a professional basketball league in the Dominican Republic * Liga Nacional de Básquetbol, an Argentine basketball league * Liga Nacional de Básquetbol, a Paraguayan basketball league * Ligue Nationale de Basket, the governing body of men's basketball in France * Ligue Nationale de Basket (Switzerland), a Swiss professional basketball league Other uses * Laredo National Bank, an American commercial bank * Level of neutral buoyancy * Low-noise block downconverter * Mbalanhu dialect of the Ovambo language * National Library of Latvia (Latvian: ') {{disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Engineering Tolerance
Engineering tolerance is the permissible limit or limits of variation in: # a physical dimension; # a measured value or physical property of a material, manufactured object, system, or service; # other measured values (such as temperature, humidity, etc.); # in engineering and safety, a physical distance or space (tolerance), as in a truck (lorry), train or boat under a bridge as well as a train in a tunnel (see structure gauge and loading gauge); # in mechanical engineering, the space between a bolt and a nut or a hole, etc. Dimensions, properties, or conditions may have some variation without significantly affecting functioning of systems, machines, structures, etc. A variation beyond the tolerance (for example, a temperature that is too hot or too cold) is said to be noncompliant, rejected, or exceeding the tolerance. Considerations when setting tolerances A primary concern is to determine how wide the tolerances may be without affecting other factors or the outcome of a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tweaking
Tweaking refers to fine-tuning or adjusting a complex system, usually an electronic device. Tweaks are any small modifications intended to improve a system. In electronics, it is a synonym for "trimming." Analog circuit boards often have small potentiometers or other components on them that are used to calibrate or adjust the board as a service procedure: the small insulated screwdriver used to turn them is often called a "tweaker." This use was echoed in the name of the product ''Tweek'', a popular but controversial audio product during the 1980s, which was claimed to improve the electrical characteristics of audio switch contacts. Hardware Hardware tweaking is a process of modifying certain parts of a hardware such as changing the cables, cleaning the heads of a VCR with a branded cleaning fluid or oiling the moving parts of an engine with the best possible oil. Computer hardware Computer hardware tweaking is an extension of hardware tweaking, specifically geared towards ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High-electron-mobility Transistor
A high-electron-mobility transistor (HEMT or HEM FET), also known as heterostructure FET (HFET) or modulation-doped FET (MODFET), is a field-effect transistor incorporating a junction between two materials with different band gaps (i.e. a heterojunction) as the channel instead of a doped region (as is generally the case for a MOSFET). A commonly used material combination is Gallium arsenide, GaAs with Aluminium gallium arsenide, AlGaAs, though there is wide variation, dependent on the application of the device. Devices incorporating more indium generally show better high-frequency performance, while in recent years, gallium nitride HEMTs have attracted attention due to their high-power performance. Like other FETs, HEMTs can be used in integrated circuits as digital on-off switches. FETs can also be used as amplifiers for large amounts of current using a small voltage as a control signal. Both of these uses are made possible by the FET’s unique current–voltage characteristic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Decibels
The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B). It expresses the ratio of two values of a power or root-power quantity on a logarithmic scale. Two signals whose levels differ by one decibel have a power ratio of 101/10 (approximately ) or root-power ratio of 101/20 (approximately ). The strict original usage above only expresses a relative change. However, the word decibel has since also been used for expressing an absolute value that is relative to some fixed reference value, in which case the dB symbol is often suffixed with letter codes that indicate the reference value. For example, for the reference value of 1 volt, a common suffix is " V" (e.g., "20 dBV"). As it originated from a need to express power ratios, two principal types of scaling of the decibel are used to provide consistency depending on whether the scaling refers to ratios of power quantities or root-power quantities. When expressing a power ratio, it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Noise Temperature
In electronics, noise temperature is one way of expressing the level of available noise power introduced by a component or source. The power spectral density of the noise is expressed in terms of the temperature (in kelvins) that would produce that level of Johnson–Nyquist noise, thus: :\frac = k_\text T where: * P_\text is the noise power (in W, watts) * B is the total bandwidth (Hz, hertz) over which that noise power is measured * k_\text is the Boltzmann constant (, joules per kelvin) * T is the noise temperature (K, kelvin) Thus the noise temperature is proportional to the power spectral density of the noise, P_\text/ B. That is the power that would be absorbed from the component or source by a matched load. Noise temperature is generally a function of frequency, unlike that of an ideal resistor which is simply equal to the actual temperature of the resistor at all frequencies. Noise voltage and current A noisy component may be modelled as a noiseless component i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Noise Figure
Noise figure (NF) and noise factor (''F'') are figures of merit that indicate degradation of the signal-to-noise ratio (SNR) that is caused by components in a signal chain. These figures of merit are used to evaluate the performance of an amplifier or a radio receiver, with lower values indicating better performance. The noise factor is defined as 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 ''T''0 (usually 290 K). The noise factor is thus the ratio of actual output noise to that which would remain if the device itself did not introduce noise, which is equivalent to the ratio of input SNR to output SNR. The noise ''factor'' and noise ''figure'' are related, with the former being a unitless ratio and the latter being the logarithm of the noise factor, expressed in units of decibels (dB). General The noise figure is the difference in decibel (dB) between the noise ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uplink
In a telecommunications network, a link is a communication channel that connects two or more devices for the purpose of data transmission. The link may be a dedicated physical link or a virtual circuit that uses one or more physical links or shares a physical link with other telecommunications links. A telecommunications link is generally based on one of several types of information transmission paths such as those provided by communication satellites, terrestrial radio communications infrastructure and computer networks to connect two or more points. The term ''link'' is widely used in computer networking to refer to the communications facilities that connect nodes of a network. Sometimes the communications facilities that provide the communication channel that constitutes a link are also included in the definition of ''link''. Types Point-to-point A point-to-point link is a dedicated link that connects exactly two communication facilities (e.g., two nodes of a network, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Satellite Earth Station
A ground station, Earth station, or Earth terminal is a terrestrial radio station designed for extraplanetary telecommunication with spacecraft (constituting part of the ground segment of the spacecraft system), or reception of radio waves from astronomical radio sources. Ground stations may be located either on the surface of the Earth, or in its atmosphere. Earth stations communicate with spacecraft by transmitting and receiving radio waves in the super high frequency (SHF) or extremely high frequency (EHF) bands (e.g. microwaves). When a ground station successfully transmits radio waves to a spacecraft (or vice versa), it establishes a telecommunications link. A principal telecommunications device of the ground station is the parabolic antenna. Ground stations may have either a fixed or itinerant position. Article 1 § III of the International Telecommunication Union (ITU) Radio Regulations describes various types of stationary and mobile ground stations, and their inter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Block Upconverter
A block upconverter (BUC) is a component used in the transmission (uplink) of satellite signals. It converts a band of frequencies from a lower frequency to a higher frequency. Modern BUCs convert from the L band to Ku band, C band and Ka band. Older BUCs convert from a 70 MHz intermediate frequency (IF) to Ku band or C band. Most BUCs use phase-locked loop local oscillators and require an external 10 MHz frequency reference to maintain the correct transmit frequency. BUCs used in remote locations are often 2 or 4 W in the Ku band and 5 W in the C band. The 10 MHz reference frequency is usually sent on the same feedline as the main carrier. Many smaller BUCs also get their direct current (DC) over the feedline, using an internal DC block. BUCs are generally used in conjunction with low-noise block converters (LNB). The BUC, being an up-converting device, makes up the "transmit" side of the system, while the LNB is the down-converting device ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
