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Diplexer
A diplexer is a passive device that implements frequency-domain multiplexing. Two ports (e.g., L and H) are multiplexed onto a third port (e.g., S). The signals on ports L and H occupy disjoint frequency bands. Consequently, the signals on L and H can coexist on port S without interfering with each other. Typically, the signal on port L will occupy a single low frequency band and the signal on port H will occupy a higher frequency band. In that situation, the diplexer consists of a lowpass filter connecting ports L and S and high pass filter connecting ports H and S. Ideally, all the lowband signal power on port L is transferred to the S port and vice versa. All the highband signal power on port H is transferred to port S and vice versa. Ideally, the separation of the signals is complete. None of the low band signal is transferred from the L port to the H port. In the real world, some power will be lost, and some signal power will leak to the wrong port. The diplexer, being a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bias Tee
A bias tee is a three-port network used for setting the DC bias point of some electronic components without disturbing other components. The bias tee is a diplexer. The low-frequency port is used to set the bias; the high-frequency port passes the radio-frequency signals but blocks the biasing levels; the combined port connects to the device, which sees both the bias and RF. It is called a ''tee'' because the 3 ports are often arranged in the shape of a T. Design Conceptually, the bias tee can be viewed as an ideal capacitor that allows AC through but blocks the DC bias and an ideal inductor that blocks AC but allows DC. Although some bias tees can be made with a simple inductor and capacitor, wideband bias tees are considerably more complicated because practical components have parasitic elements. Bias tees are designed for transmission-line environments. Typically, the characteristic impedance will be 50 Ohms or 75 Ohms. The impedance of the capacitor () is chosen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Duplexer
A duplexer is an electronic device that allows bi-directional ( duplex) communication over a single path. In radar and radio communications systems, it isolates the receiver from the transmitter while permitting them to share a common antenna. Most radio repeater systems include a duplexer. Duplexers can be based on frequency (often a waveguide filter), polarization (such as an orthomode transducer), or timing (as is typical in radar). Types Transmit-receive switch In radar, a transmit/receive (TR) switch alternately connects the transmitter and receiver to a shared antenna. In the simplest arrangement, the switch consists of a gas-discharge tube across the input terminals of the receiver. When the transmitter is active, the resulting high voltage causes the tube to conduct, shorting together the receiver terminals to protect it, while its complementary, the anti-transmit/receive (ATR) switch, is a similar discharge tube which decouples the transmitter from the antenna while n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electronic Component
An electronic component is any basic discrete device or physical entity in an electronic system used to affect electrons or their associated fields. Electronic components are mostly industrial products, available in a singular form and are not to be confused with electrical elements, which are conceptual abstractions representing idealized electronic components and elements. Electronic components have a number of electrical terminals or leads. These leads connect to other electrical components, often over wire, to create an electronic circuit with a particular function (for example an amplifier, radio receiver, or oscillator). Basic electronic components may be packaged discretely, as arrays or networks of like components, or integrated inside of packages such as semiconductor integrated circuits, hybrid integrated circuits, or thick film devices. The following list of electronic components focuses on the discrete version of these components, treating such packages as com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Satellite Television
Satellite television is a service that delivers television programming to viewers by relaying it from a communications satellite orbiting the Earth directly to the viewer's location. The signals are received via an outdoor parabolic antenna commonly referred to as a satellite dish and a low-noise block downconverter. A satellite receiver then decodes the desired television program for viewing on a television set. Receivers can be external set-top boxes, or a built-in television tuner. Satellite television provides a wide range of channels and services. It is usually the only television available in many remote geographic areas without terrestrial television or cable television service. Modern systems signals are relayed from a communications satellite on the X band (8–12 GHz) or Ku band (12–18 GHz) frequencies requiring only a small dish less than a meter in diameter. The first satellite TV systems were an obsolete type now known as television receive-only ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Single Cable Distribution
Single-cable distribution is a satellite TV technology that enables the delivery of broadcast programming to multiple users over a single coaxial cable, and eliminates the numerous cables required to support consumer electronics devices such as twin- tuner digital video recorders (DVRs) and high-end receivers. Without single-cable distribution, providing full-spectrum access for multiple receivers, or receivers with multiple tuners, in a single-family home has required a separate coaxial cable feeding each tuner from the antenna equipment (either multiple LNBs, a multi-output LNB or a multiswitch distribution system) because of the large bandwidth requirement of the signals. Single-cable distribution technology enables one coaxial cable from the antenna equipment to multiple tuners, to provide independent tuning across the whole range of satellite reception for each tuner. A European industry standard for distributing satellite signals over a single coaxial cable - CENELEC EN50 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Set-top Box
A set-top box (STB), also colloquially known as a cable box and historically television decoder, is an information appliance device that generally contains a TV-tuner input and displays output to a television set and an external source of signal, turning the source signal into content in a form that can then be displayed on the television screen or other display device. They are used in cable television, satellite television, and over-the-air television systems as well as other uses. According to the ''Los Angeles Times'', the cost to a cable provider in the United States for a set-top box is between $150 for a basic box to $250 for a more sophisticated box. In 2016, the average pay-TV subscriber paid $231 per year to lease their set-top box from a cable service provider. TV signal sources The signal source might be an Ethernet cable, a satellite dish, a coaxial cable (see cable television), a telephone line (including DSL connections), broadband over power lines (BPL) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Integrated Receiver/decoder
An integrated receiver/decoder (IRD) is an electronic device used to pick up a radio-frequency signal and convert digital information transmitted in it. Consumer IRDs Consumer IRDs, commonly called set-top boxes, are used by end users and are much cheaper compared to professional IRDs. To curb content piracy, they also lack many features and interfaces found in professional IRDs such as outputting uncompressed SDI video or ASI transport stream dumps. They are also designed to be more aesthetically pleasing. Professional IRDs Commonly found in radio, television, Cable and satellite broadcasting facilities, the IRD is generally used for the reception of contribution feeds that are intended for re-broadcasting. The IRD is the interface between a receiving satellite dish or Telco networks and a broadcasting facility video/audio infrastructure. Professional IRDs have various features that consumer IRDs lack such as: * SDI outputs. * ASI inputs / outputs. * TSoIP inputs. * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RG-6
RG-6/U is a common type of coaxial cable used in a wide variety of residential and commercial applications. An RG-6/U coaxial cable has a characteristic impedance of 75 ohms. The term, ''RG-6'', is generic and is applied to a wide variety of cable designs, which differ from one another in shielding characteristics, center conductor composition, dielectric type and jacket type. ''RG'' was originally a unit indicator 'Mike Meyers' CompTIA Network+ Certification Passport', by Glen E. Clark, edited by Christopher A. Crayton, McGraw-Hill, 3rd Edition, 2009, page 32. "Specific coax types were developed for the Ethernet standard, but a number of radio cables have very similar characteristics, and these so-called radio-grade (RG) cables also became associated with Ethernet." for bulk radio frequency (RF) cable in the U.S. military's Joint Electronics Type Designation System. The suffix ''/U'' means ''for general utility use''. The number was assigned sequentially. The ''RG'' unit in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RG-59
RG-59/U is a specific type of coaxial cable, often used for low-power video and RF signal connections. The cable has a characteristic impedance of 75 ohms, and a capacitance of around 20pF/ft (60pF/m). The 75 ohm impedance matches a dipole antenna in free space. ''RG'' (for ''radio guide'') was originally a unit indicator for bulk radio frequency (RF) cable in the U.S. military's Joint Electronics Type Designation System. The suffix ''/U'' means ''for general utility use''. The number ''59'' was assigned sequentially. The ''RG'' unit indicator is no longer part of the JETDS system (MIL-STD-196E) and cable sold today under the RG-59 label does not necessarily meet military specifications. RG-59 is often used at baseband video frequencies, such as composite video. It may also be used for broadcast frequencies, but its high-frequency losses are too high to allow its use over long distances; in these applications, RG-6 or RG-11 are used instead. In cases where the transmi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DiSEqC
DiSEqC (; short for Digital Satellite Equipment Control) is a special communication protocol for use between a satellite receiver and a device such as a multi-dish switch or a small dish antenna rotor. DiSEqC was developed by European satellite provider Eutelsat, which now acts as the standards agency for the protocol. History Eutelsat apparently developed the system to allow satellite users in Continental Europe to switch between the more popular SES Astra satellites at 19.2° east and Eutelsat's own Hot Bird system at 13° east. As a result, the vast majority of European satellite receivers support DiSEqC 1.0 or higher, with the exception of all set top boxes manufactured under the Sky Digibox name. All supporting receivers have received certification to carry a logo specifying which variation of DiSEqC they support. Protocol DiSEqC relies only upon a coaxial cable to transmit both bidirectional data/ signals and power. DiSEqC is commonly used to control switches and m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Block Converter
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] |
Television Channel Frequencies
The following tables show the frequencies assigned to broadcast television channels in various regions of the world, along with the ITU letter designator for the system used. The frequencies shown are for the analogue video and audio carriers. The channel itself occupies several megahertz of bandwidth. For example, North American channel 1 occupies the spectrum from 44 to 50 MHz. See Broadcast television systems for a table of signal characteristics, including bandwidth, by ITU letter designator. VHF Americas (most countries), South Korea, Taiwan, Burma (Myanmar) and the Philippines During World War II, the frequencies originally assigned as channels 13 to 18 were appropriated by the U.S. military, which still uses them to this day. It was also decided to move the allocation for FM radio from the 42-50 MHz band to a larger 88-106 MHz band (later extended to the current 88-108 MHz FM band). This required a reassignment of the VHF channels to the plan cu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
