Global System TV Solution Provider

Global System TV Solution Provider

Satellite TV

Homepage    Professional Learning Documents    Satellite TV

Satellite TV

Analogsimulation letterit is a continuously variable signal, such as human voice, music and TV images.early satellite communication systems were basically analog signals transmitted.
Apogeefar awaypointsatellite. Synchronous geo orbiting the earth in a circular orbitstaris launched, it is first sent into an elliptical orbit.35,888kilometers of apogee, then ignite the small satellitehelppush the rocket, with the help of the thrust of this rocket, the satellite enters and runs all the time.in35,888kilometers.
ATM (Asynchronous Transfer Mode)Asynchronous transfer modeis used in broadband digital networks, in units of cells,A way to transmit information between devices. Any type of letter can be carried in the cell carrier.interest(Multimedia such as video, voice, and image)to operate at high speed. passMexchangemachineEstablish a connection between the source and the destination. When the connection is established, any communication can be made between the devices.
Attenuationdeclineminusthe process of reducing the input signal level to avoid receiver overload. The attenuator is onespeciespassive devices are usually placed between satellite receivers and coaxial cables. In the differential TV system,those users who are very close to the differential station often use attenuators to reduce the signal level too strong.
Azimuth (AZ)bearingangleWhen tracking a synchronous earth satellite, the parabolic antenna of the satellite ground stationinan angle that must be rotated in the horizontal direction. For any ground station, onlyknowing the longitude of the tracking synchronous satellite, the azimuth angle of its antenna can be determined.
BB (Base Band)basebeltTV camera, satellite TV receiver or video recorder output6MHzbandwidth signal.Only the monitor can display the baseband signal.
Beta Format BetasystemBetasystem is a household video recorder system developed by Sony.this systemandVHSis incompatible.
Birda communication guardstara typical communications satellite, weighing about thousands of pounds and having an average service life of seven years, is connected.often"stop"is at a distance from the ground.ball35,888kilometers. The communication satellite seems to act like an electronic mirror, forwarding by various places.surfacetelephone, television and data signals sent by communication networks and ground stations, and transmit these signals to the corresponding satellite ground stations.
bit ratebitratebits of the compressed code stream transmitted from the channel to the input of the decoderrate/The code rate.
BlankingInter-frameseptumconventional TV signals, it is transmitted every second.delivery25still screenor25Frame images. Frame interval time refersisthe time interval between the end of one frame and the end of the next frame. With this interval, some data signals can be transmitted.,but ordinary TV sets cannot receive these data signals.
BNC Connector BNCheadstandardized small bayonet coaxial cable connector.
C/N (Carrier/Noise)load noiseratioof Satellite Signal Power and Receiving Noise Powerratio(dBtable),ratio, the better the TV image quality.whenC/Non7dB, electricitythe quality of the image is very bad.,C/Nhighon11dB.
Carrierloadwavethe center frequency of the signal transmitted by a radio or television transmitter. The carrier is usually AM or FM,in analog satellite TV, the carrier wave is frequency modulated to transmit image signals and accompanying sounds.
Carrier Frequencycarrier frequencyratethe operating frequency of a radio station, television station or microwave transmitter. AM broadcasting workerfrequency isfrom535~1600KHz. The operating frequency band of FM broadcasting isfrom88~108MHz. Terrestrial TVstationisfrom54-890MHz. The operating frequency band of the transmitter of the microwave and satellite communication system isfrom1~14GHz.
Cassegrain AntennaCassegren Dayline(line)satellite TV receptionsome secondary reflection structures not only eliminate the huge feeder support, but also retain the advantages of long focal length and high gain.
CATV Convertercable TV channel pre-selectioncable TV system, a special connection between TV and cabledevice, which replaces the high-frequency head of the TV set, enables users to choose TV programs of various channels transmitted by cable at will.
C- BandCwavefrequencyfrom3.7-4.2GHzis used as the frequency band for downlink transmission signals of communication satellites.
CDTV (conventional definition television)ordinary definition electricityis used to meanITU-R470recommendationsmoduleproposedNTSCTV system.
Channelletterroada frequency band that transmits a specific signal.
Chrominance (chroma)colordegreethe color information of the video signal
Circular polarizationcircle poleInternational Communications Satellite uses circularly polarized antennas to transmit signals to the ground in a spiral form.Some communication satellites are transmitted at the same frequency according to the left spiral and the right spiral.two different signals, thus doubling the channel capacity of the satellite.
C Clark OrbitClark synchronous earth orbitroadearth synchronous satelliteball35,888kilometers of circular orbit, thistrack was made by science fiction writer Ya·Clark in the late 1940 sin"radio worldboundary"magazine first proposed.satellite in this orbit, although rotating around the earth at a speed of thousands of kilometers per hour, due to the rotation of the earthis the same as that of this satellite. So from a corresponding point on the earth, the satellite and the earth are always relatively stationary.
Coaxial Cablecoaxial electricitycablea transmission line whose center conductor and outer conductorbody(or shieldinglayer).cable TV uses coaxial cable to transmit TV signals. Home Satellite TV Receiving AntennaandThe high frequency heads of the receiver are usually connected by coaxial cables..Compressionpressureshrinkagerefers to reducing the number of bits used to represent information.
CRC (Cyclic Redundancy Code)Cyclic redundancycodeThe bit added to the information bit to detect the correctness of the data.
D/C (Down Converter)down conversionone of the components of the satellite TV receiver, the main function is to transfer microwave signals from the satellite,is converted down to an intermediate frequency signal. At present, the downconverter, low noise amplifier and feed are integrated to facilitate the use of generalcable TV transmits the intermediate frequency TV signal to the receiver.
dBmdB millitilesignal power in decibelsand1mW reference power source ratio.
DBS (Direct Broadcast Satellite)Live Guardstarits operating frequency bandin12GHzabove. Due to the direct broadcast satelliteoperating frequency is very high and the transmission power is greatly increased, so the antenna size of the ground receiver can be greatly reduced and suitable for personal direct viewing.
Demodulatordemodulationreceivers to restore sound or image signals from carrier signals.
Digitaldigital letterdiscrete variable quantity, a typical digital signal has two"shapestate",indicates two different signal conditions.
Dipoledipolar skylinecommonly used horn TV antenna is a simple dipole antenna..satellite TV antenna is also a dipole antenna.
Direc PCis a way to connect personal computers via satellite.INTERNETservice technology
Dish-Stretching Technology (or Threshold Extension Technology)Threshold Extension Technologyis used to reducenoise on TV screens. One is the received imagetechnology, the other is IF filtering technology. Because the noise is suppressed, the antenna can be reducedsize or think that because this technology has improved the signal-to-noise ratio, it is equivalent to lowering the threshold.
Distribution Amplifierallocation amplificationcable TV system is used to transmit TV signals to the cable network.lineZoom in. The shared antenna system of apartment buildings and hotels often uses distribution amplifiers to increase the load capacity of the antenna system..Distribution CenterTV broadcaststation(or on TVheart)TV station is responsible for transmitting programs fromdeliveryorganization is transmitted to the sub-stations and users of the TV network.
Ditheringenergy expansionscatteredin bandwidthis36MHzsatellite transponder,12.5Hztriangular wave takes bandwidthis6MHzTV signal. This process of satellite TV signals actually expands the signal energy to a wider frequency.belt, this frequencybelt(36MHz)is much larger than the working bandwidth of the terrestrial TV microwave transmitter, thus reducing the interference to the terrestrial microwave transmitter.
Down LinkDownstream frequencyroadcommunication satellites relay channels that forward television signals to ground stations.
Earth Stationgroundstationon earth, the receiving system that receives signals from satellites mainly consists of antennas and low noisesoundamplifier, down converter and receiver are combined. Ground station antenna size usuallyfrom2.4meters~27meters.EIRPomnidirectional effective radiation workrateMeasurement of Satellite TV Signal Power Received by Satellite Ground Station.EIRPdBW(decibelstile). Usually before launching a satellite, it is necessary to count.EIPRstrength. The calculation results can be plotted as receiving at each point in the satellite beam coverage area.satellite signal strength change. The ground station receivesEIRPstrength and the required antenna size.
Elevation (EL)tiltanglethe elevation angle of the earth station antenna aiming at the satellite,"degree"to measure, if the antenna is aligned with the horizon,is the elevation angleis0°, if the antenna is directly aimed at the satellite overhead, the elevation angleis90°.entropy codingEntropycodeis a variable word length lossless coding method used to reduce the redundancy of digital signals.F/D (Focal -Length-to-Diameter ratio)focal length diameterratiosatellite
FEC (Forward Error Correction)forward error correctionerrorminingMPEG-2TechnologyOne of the parameters.is1/2,3/4,5/6,7/8, etc.
Feed-hornfeed labeepa component on the satellite TV receiving antenna, its function is to make the reflection surface from the antenna weaksignal is focused, it is fed into the low noise amplifier.
Feed-linelineis used for the transmission line between the antenna and the receiver. The typical feeder is a coaxial cable.
Field Strength Meterfield strengthinstrumentmeasuring instrument used to measure signal power on transmission lines or antennas.
FM (Frequency Modulation)frequencymakes the frequency of a sinusoidal carrier change according to the strength of a certain audio and video signal.the modulation process, the modulated carrier wave is transmitted with an antenna to become an FM radio or FM TV signal.
FM ThresholdFM doorFM receiver demodulator is called the threshold level,If the input signal is lower than this level, the demodulator cannot recover the complete original signal from the carrier.
Footprintsatellite radiation field strengthTV Satellite Beam Coverage AreaEIRPa graph composed of intensity contours. The chartpoints on the groundEIRPstrength. Different transponders on the same satellite have their own differences.EIRPField strength chart.
Frequency Reusefrequency complexuse the geometric position of the satellite or the polarization mode of the antenna to separate the signal, andthis technology to expand the channel capacity in the limited frequency band. A Common Method of Frequency Reuse in Domestic Satellite Communication Systemsismake two satellites working in the same band phase in orbitdistance4°, becauseis3~4GHzBandwidthdegreeis2°, so yes"one"satellite is impossible to receive the incoming phase.distance4°"II"satellite's signal, although both satellites work in the same frequency band. The second technology is to use antennasthe difference between horizontal polarization and vertical polarization to achieve frequency reuse. Therefore, the current satellitehave24horizontal polarizationanda vertically polarized transponder.24channels of television, and according to conventional technology can only be transmitted12road TV.
Frequency-AgileChannel Optionalsexdescribes a satellite TV receiver, select from satellite12or24a letterroad(each transponder works on a letterroad)ability. If a receiver has no channel selectability, it is said thatMingThe receiver only receives a single channel.
Gainincreasebenefitthe ratio of a system output signal to the input signal level, usually dividedshellfish(dB)to measure.
Geosynchronoussynchronous earth orbitroadis located over the equator and away from the earth's surface.surface35,888public(2)2,300English)'s circular orbit around the earth.GHzgigahertz(frequency listbit),1GHz = 1000MHz, usually high frequencyon1gigahertz are called microwave signals.frequency begin to have some characteristics of visible light.
Global Beamglobal wavebundlea form of downgoing beam of a global international communications satellite, the beam of a satellite can becovers the 1/3 area of the earth. The global beam consists of three communication guards located over the Atlantic, Pacific and Indian Oceans.starcomposition, because the beams of these three satellites cover the entire surface of the earth, so that any area around several oceans can beto the same signal. Because the global beam coverage is much larger than that of domestic satellites covering only one region, the Global Satellite LetterEIRPstrength is very weak, so the ground station receiving the global satellite signal requires a large antenna, typical diameterin9meters or more.
GMT (Greenwich Mean Time)GreenwichroomInternational Standard Time
Gorizont (Horizon)of the horizontal linemeansis a CIS geostationary satellite
GregorianGregorianlineis composed of a double reflector antenna, the convex hyperboloid is the secondary reflector, and the paraboloid is the main reflector.
G/T (Gain/Temperature)Quality of Ground Receiving SystemSatellite TV Receiving Systemsystemnoise is expressed in decibels. If this value increases, it means that the image quality is improved. Utilization reductionthe noise temperature of the low noise amplifier and increasing the size of the receiving antenna can be increased.G/T.
Guard Channelfrequency protectionbeltTo avoid serial interference between adjacent channels. Among the adjacent TV channelsroomare all leftMHzblank band
Hertz (Hz)Hertz(frequency listbit), a change of one hertz per second.Huffman codingedited by Hoffmancodeit is an entropy coding method. It uses different lengthscodeto indicate that the probability of occurrence is different.Heliaxspiral electricitycablespecial coaxial cable with very low transmission loss in microwave frequency band is often used to connect antenna and receiver.
ISDB (Integrated-services Digital Broadcasting)The number of integrated services is wide.broadcastcombines various signals including still images and live imagesmovementimages, sounds, files, characters and other types of data are integrated and transmitted in a single transmission channel.
Ka-band Kawaveroughly the frequency rangeis30/20GHz Kelvinkell(absolute temperature listbit)a commonly used unit of temperature measurement in science and technology,K's zero indicates physicsAbsolute zerodegree(is equivalenton-273). The thermal noise characteristics in the amplifier are measured by absolute temperature.
Ku-Band Kuwavefrequencyfrom11~14GHzband, used for satellite communication and live satellite TV.
L-bandLwavein a satellite receiver, its frequency range is aboutis950~2150 MHZ LevelelectricityflatLNA (Low Noise Amplifier)low noise amplificationa high-sensitivity preamplifier, usually connected to the ground station antennafeed horn is used to reduce the noise temperature of the receiving system and increase its total gain. Low noise amplifier is the most importantindicator is noise temperaturedegree(Use absolute temperaturedegreeKtable)generally speaking, the lower the noise temperature, the better the TV signal quality.
LNB (Low Noise Block)high frequencyheada component composed of a low noise amplifier and a down converter,LNB=LNA LNC LNC (LowNoise Converter)low noise frequency conversion(down conversion)
LPTV (Low-power TV)low power electricityby the Federal Communications Commissionin1980,low-power TV stations is onlyin100~1,000between the tiles, the beam coverage radiusis16~24kilometers.
MATV (Master Antenna Television)shared antenna television systemsystemare often used in apartment buildings, hotels, etc.,this system can be incorporated into the cable TV system with a slight improvement.
MCPC (Multi Channel Per Carrier)Multiple single loadwavein satellite digital TV transmission, multiple sets of TV program codesstreamis mixed by the multiplexer, it is modulated on a carrier frequency and then transmitted. After receiving the frequency at the ground receiving station,will demodulate and decode the code stream, after the splitter to take out multiple sets of programs, and then after processing, you can see multiple sets of TV programs.
MDS (Multi-point Distribution System)Multi-ApsaraVideo for VODthis kind of system in the city, like radio broadcast electricitystationtransmits TV signals without direction, but the receiving point is limited and specific.
MMDS (Multi-channel Microwave Distribution System)Multi-channel Microwave Distribution Systemsystemmining2.4-2.6GHzfrequency microwaves can transmit TV signals in a directional or multi-directional manner.MPEG-1meansISO/IECStandard.11172-1(system)11172-2(frequency),11172-3(soundfrequency)11172-4(consistency measurementtest)and11172-5(Technology Newsreport).
MPEG-2meansISO/IECstandard,13818-1(system),13818-2(frequency),13818-3(soundfrequency),13818-4(sex).Offset Antennalinethe reflector of this antenna is only a part of the paraboloid of revolution, usually including poles or vertices,When feedforward is used, there is no aperture blockingN.T. (Noise Temperature)noise temperaturedegreeparameters used to represent the noise characteristics of electronic equipment systems or devices, oftenKNTSC (National Television Standards Committee)National Television Standards CommitteewillAmerican TV system by this committeewilldecision,NTSCis also the code name of the American color TV system.NTSCsystem is characterized by transmission per second.delivery30frame525.
PAL (Phase Alternation by Line)a Color TV SystemColor TV Coding System Designed by Germany,PALmeans line-by-line phasesystemParaboloidrotating parabolicsurfacethe shape of the classic antenna reflecting surface
PCM (Pulse Code Modulation Coding system)pulse code modulationsystemcoding system for digital transmission
PID (packet Identifier)Package recognitionin a single program or multi-program transmission stream, used to accompany the basic streama specific integer value for the decoder to identify the code stream properties.
Pixellikeelementrefers to one of brightness or chromaticity8bit sampling.
Radio Frequency SpectrumRFspectrumin the electromagnetic spectrum, the frequency ranges from several hundred kHz to several gigahertzrange is called radio frequency spectrum or radio spectrum.
RF Adapterradio frequency modulationis installed between the output of the satellite TV receiving terminal and the input of the user TV.Additional modulators. The RF add-on modulates the baseband TV signal from the satellite TV receiver.isradio frequency signals so that the user's ordinary TV set can receive these signals on specific TV channels.
RGB (Red,Green,Blue)Red, Green,blueTV
SatelliteguardstarIn space, any smaller asteroid body orbiting a larger planet in a fixed orbit is called a satellite..like the moon is the natural satellite of the earth. Artificial earth satellites follow their respective orbits and use the rotation of the earthaxisrevolves around the earth. Almost all communication satellites are launched into synchronous earth orbit.
Satellite Receiversatellite receptionmachinebroadband FM receiver operating in microwave band, the main functions areCwaveorKuband satellite analog TV signals are restored to baseband TV signals.
Satellite Terminalsatellite reception terminalsatellite ground station with only receiving capability consists of parabolic antenna,feed horn, low noise amplifier, down converter and satellite receiver.
S-BandSwavesatellite downlink frequency rangein2.6GHz
SCPC (Single-Channel-Per-Carrier)waveitandMCPCdifference is that all the TV programs are modulated separately.intransmit at a carrier frequency, and the receiver can transmit at the corresponding frequency.the program. At present, most provincial digital satellite TV is adopted.SCPCbroadcast.
Scramblingdisturbancecodedeliberately change the characteristics of video, audio, or encoded code streams to prevent them from being received by unauthorized persons. Of course thischanges are handled according to regulations under the control of the conditional receiving system, and sometimes this is also done in order to disperse the spectral energy of the signal.
SDTV (standard definition television)ordinary definition electricityis used to refer to a digital television system.,its quality is basically equivalentonNTSC. This term is also called ordinary digital TV.
SECAM (Sequential Color Memoire) SECAMcolor systemthe color TV system adopted by France and the Soviet Union,andPALis incompatible.SECAMmeans sequential color TVmemoryS/N (Signal/Noise)ratiosignal power to noise power is dividedshellfish(dB)indicates.S/Non TVisan extremely important performance index.
Sparklesnoisepointsatellite TV system, noise causes interference and miscellaneous points on TV screen.,"noisepoint"than the usual terrestrial television system"snowflakespoint"is more obvious. eliminationDivision"noisepoint"only addground station antenna size and use low noise amplifier with lower noise temperature.
Spherical Antennaspherical skylineanother major form of satellite ground station antenna. Unlike parabolic antennas, spherical skylinecan aim at several satellites at the same time, so it has the ability to receive several satellite signals at the same time. Because of thisonecharacteristics, more and more domestic satellite TV receivers have begun to install spherical antennas because,these users hope to be able to easily switch from receiving one satellite to receiving another satellite.
Spot Beampoint wavebundlebeam is circular or elliptical, covering a certain area of the earth's surface. This beam is smaller than the global beam.
STV (Subscription Television)Timed Toll Broadcastinga paid radio and television service.
Sub-carriersecondary loadwavethe carrier frequency of transmitting audio and other information in TV signals.
Synchronizationsteptechnology that keeps the signals of both transceiver and transmitter at the same pace in time.
Teleconferencetelephone conferencemany people who are not in the same place use some electronic devices such as telephones and televisions..computer terminals, etc.
Teletextgraphic electricity"graphic electricity"is transmitted simultaneously with the TV signal and can display text and images on the TV screen.,are there usually"",every""containshave20Chinese and English."graphic electricity"deputycarrier wave is transmitted by using frame blanking time in TV signal. Ordinary TV sets cannot be accepted.look"graphic electricity", the TV set is attached with special"graphic electricity"decoder to watch"graphic electricity". Now Xutelevision networks and satellite television systems have increased."electronic newspaper graphic electricity"signal.
Terrestrial TVterrestrial broadcast electricityground transmission within a limited range, transmission rangeisstraightdiameter160kilometers, operating frequency bandVHF~UHF.
Threshold Extensionthreshold expansionexhibitiona way to improve the signal-to-noise ratio of satellite receiversnear3decibel technology.
TranslatorTV Differencemachinedifferential transfer is to receive remote TV signals.,then converts the TV signal into another channel and transmits it to the region to increase TV coverage.
TransponderForwardingconsists of a receiver, a transmitter and an antenna, and is an integral part of the satellite entity. Typical passlettertransponder transmit poweris5~8.5tile,(At present, the transmission power of satellite TV transponders is about tens of watts to 100 watts.,)Cband operating frequencyrate4~6GHz, beltwidth36MHz.andKubandis12~14 GHzis54MHz,a group of communication satellites usuallyhave12~24a transponder.
Twin Leadparallel feedline1950 s,has now been replaced by better-performing coaxial cables.
UHF (Ultra High Frequency)UHF wavefrequencyin300MHz~3GHz. Radio and television band on the groundis470~890MHz
UplinkThe uplink frequencyroadthe channel that the satellite ground station of the center transmits information to the satellite.
Vertical BlankingFrame cancellationhiddenThe process of eliminating interframe flybacks.
VHF (Very High Frequency)is very high.frequencyfrequency rangefrom30MHz~300MHz.
VHS Format VHSone of the two most common home video recorder formats, the otherisBeta
Video MonitormonitoringTV sets without high frequency heads can only receive baseband TV signals, notVHFandUHFradio and television signals. The monitor has higher resolution and image quality than ordinary TV sets.
Waveguidewaveguiderectangular or elliptical sections are used for microwave signal transmission.
Wind Loadingnegative wind pressurelotusthe pressure exerted by the wind on the receiving antenna of the satellite ground station. A well-designed parabolic antenna shouldenergybear wind speed for each small64kilometers of wind pressure load, and there will be no obvious damage, even should resist every small160kilometers of wind speed.

surface acoustic wave filter(SAWF)
surface acoustic wave filter is made of the piezoelectric effect of quartz, lithium niobate and barium titanate crystals. The so-called piezoelectric effect is the phenomenon that when the crystal is subjected to mechanical action, an electric field proportional to the pressure will be generated. Crystals with piezoelectric effect will also produce elastic deformation and emit mechanical waves (sound waves) when subjected to electrical signals, which can convert electrical signals into acoustic signals. Since this kind of sound wave only propagates on the surface of the crystal, it is called a surface acoustic wave..SAW FilterisSAWF, surface acoustic wave filter has the advantages of small size, light weight, reliable performance and no complicated adjustment. The key device to realize adjacent frequency transmission in cable TV system. The characteristics of the surface acoustic wave filter are:(1) The frequency response is flat, and the unevenness is onlyis± 0.3-± 0.5dBextension± 30-± 50ns.(2)SAWFrectangle coefficient is good, out-of-band suppression can beda40dBabove.(3) Although the insertion loss is highda25-30dB, but the amplifier can be used to compensate for the level loss..surface acoustic wave filter includes surface acoustic wave television image intermediate frequency filter, television sound filter and television channel residual sideband filter. The typical technical indexes of surface acoustic wave filter are shown in the following table.
comb filter
comb filter consists of many passbands and stopbands arranged at certain frequency intervals, only allowing signals in certain frequency ranges to pass through. The characteristic curve of the comb filter is like a comb, so it is called a comb filter..comb filter has many applications in TV technology. Comb filters are used to separate two orthogonal fractions of chrominance signalsquantityUcolor difference signalandVColor difference signal. Comb filter is generally composed of delay, adder, subtractor and band pass filter. For still images, comb filtering is performed between frames, that is, three-dimensional comb filtering. For moving images, comb filtering is performed within the frame, that is, two-dimensional comb filtering. Except for special requirements, most digital TV equipment or high-quality digital TV receivers use a row-delay comb filter and a band-pass filter cascade.Y,Cseparation scheme..using comb filter can obviously improve the image quality. Solve the interference light spot and interference pattern caused by bright color string and bright color string; eliminateU,Vmixing; Eliminate bright and colored borders.
attenuator
a circuit for introducing a predetermined attenuation within a specified frequency range. Generally, the number of decibels of the attenuation introduced and the ohmic number of its characteristic impedance are used to indicate.attenuators are widely used in cable TV systems to meet the level requirements of multiple ports. Such as the control of the input and output levels of the amplifier, and the control of the amount of branch attenuation. There are two types of attenuators: passive attenuators and active attenuators. The active attenuator cooperates with other thermal components to form a variable attenuator, which is used in the amplifier for automatic gain or slope control circuit. Passive attenuators have fixed attenuators and adjustable attenuators. The fixed attenuator is composed of resistors and does not affect the frequency characteristics.Torπnetwork composition;75ΩresistanceresistanceT,πtype resistance data with different attenuation can be found in the book Shared Antenna TV System); the adjustable attenuator is composed of potentiometers for use in debugging and level adjustment.requires that the input and output impedances of the attenuator should match the interface terminal, and both in the cable TV system shouldis75. The frequency characteristics of the attenuator must meet the frequency range requirements of the system, and the attenuation of the attenuator in the frequency range should be independent of the frequency. Therefore, the composition of commonly used resistance elements.the frequency range is different, the form of attenuator is also different. Coaxial lines are used as attenuators; in waveguide systems, diaphragms that absorb electric field energy are commonly used as attenuators; solid-state diodes are also used (PINdiode) is an electrically tunable attenuator made of waveguide or coaxial system in microwave frequency band. Attenuators are commonly used in a variety of telecommunications equipment and electronic instruments.
equalizer
in telecommunication equipment, it is used to correct networks with different attenuation (I. e. transmission losses) and phase differences caused by different frequencies. Can correct the relationship between attenuation and frequency, saidis"attenuation equilibrium"; Can correct the relationship between phase difference and frequencyis"phase equalization".often need to use equalizers in cable TV systems. The equalizer is usually connected in series in the circuit of the amplifier, and is set to balance the inconsistent attenuation of high-frequency and low-frequency signals caused by cable transmission. Because the attenuation characteristics of the cable increase with the increase of frequency. Commonly used attenuation equalizer, also known as amplitude equalizer. Generally composed of coils, capacitors, resistors and other components. The characteristic impedance of the attenuation equalizer is equal to a fixed value, and its equilibrium value is the decibel difference of the attenuation between the high and low frequency reference points of the cable. The frequency characteristic of the equalizer is exactly the opposite of the cable frequency characteristic, but the frequency is low and the attenuation is large. High attenuation is small, and this opposite characteristic plays a balancing role. The equalizer is also often made into a small printed board plug-in structure, divided by the size of the balance.
mixer
mixing more than two sets of radio frequency programs (signals) of different frequencies together to form a broadband radio frequency (signal) multi-channel program output device is a mixer. In the front end of the cable TV system, the mixer is the distribution point of the system signal, that is, all the technically processed multi-channel RF signals are concentrated at the mixer input, and then the signals are output at the mixer output and distributed to the system network to the user..mixer. Operating frequency: If the mixer is of broadband type, the frequency shall meet the requirements of the whole frequency band in the system. If the mixer is of channel type, the frequency shall meet the requirements of each channel required for mixing. Access loss: when the signal passes through the passive network, the smaller the access loss (insertion loss), the better. The ratio of the input power to the output power of the mixer is called the access loss of the mixer. Access losses are usually expressed in decibels. When expressed in decibels, it is the difference between the input level decibels and the output level decibels. Different mixers have different access losses. Input and output impedance: In order to match all interfaces in the whole system, the impedance of the input and output of the mixer are bothshould75Europe; Isolation between input terminals; Under ideal circumstances, when a signal is added to any input terminal of the mixer, the signal cannot appear at other input terminals, and when any input terminal has an open circuit or short circuit phenomenon, other input terminals should not be affected. But in fact there is always a certain impact. In the case of matching of the ends, a signal is added to one input terminal, and the difference between the signal level and the signal level occurring at the other input terminals is the mutual isolation between the input terminals of the mixer, which is generally represented by a partition. There are different requirements for different mixers, generally largeon20decibels.
mutual modulation ratio(IM)
cable TV system amplifies the TV signals of multiple channels, due to the nonlinear effect of the amplifier (mainly the secondary term), the transmitted signals are mixed with each other, and the resulting sum frequency or difference frequency falls to the frequency range of the channel to be received. When the useful signal enters the TV receiver together, interference will occur, which is called mutual modulation for short. Mutual modulation is closely related to frequency. Intermodulation interference, it produces mesh or twill interference. definition of intermodulation ratioisIM=20lgThe carrier level is valid.value/intermodulation products are effectivevalueNational StandardsIM57dB, design should be58dB.
Crosstalk modulationratio(CM)
cable TV system amplifies the TV signals of multiple channels, due to the influence of the non-linear devices in the amplifier (mainly cubic terms), the image carrier of the desired received channel is affected by the amplitude of the modulation wave of other (interference) channels Change interference, this is called cross-interference modulation or cross-modulation for short. A common phenomenon is the negative image of the interfering channel image on the background of the image to be received. Sometimes the horizontal synchronization signal of the interference channel flips on the image screen to be received, forming a vertical white bar, and moving left and right (fixed when the line frequency is consistent), like a wiper on the front window of a car, soalso?quot;wiper is drydisturbance".
cross-interference modulation is the modulation of interference signal transferred to the carrier of useful signal. Define cross-disturbing modulation:XM=20lgon-carrier transfer modulation under testpeak-peakvalue/on the carrier to be modulatedpeak-peakvalueand Locust Nuo Mao Poorcaries-M):CM=20lgon the carrier to be modulatedpeak-peakvalue/on-carrier transfer modulation under testpeak-peakvalueNational StandardsCM46dB, design should be48dB.
100, distributor
distributor is the most commonly used component in the distribution network in the cable TV transmission system, and is used to distribute signals. Its function is to divide one input signal into several outputs equally, usually with two distributions, three distributions, four distributions, six distributions, etc..the frequency and function of the cable TV network are constantly increasing, the requirements for distributors are constantly increasing. The main technical requirements of the distributor. Frequency range: The distributor is used in the entire cable TV network, so it should have broadband frequency characteristics; input and output impedance: the various interface impedances of the radio frequency in the cable TV network should beis75ohms to achieve impedance matching, so the impedance of the distributor input and output should beis75Europe; Distribution loss: In the system, it is always hoped that the smaller the loss of the access distributor, the better. Distribution losslossLsand distribution roadsnis related, in an ideal situationLs=10lgn,whenn=2is3dB. In fact, in addition to the loss of the aliquot signal, there is also a part of the distribution device itself due to the attenuation, so it is always larger than the calculated value. Such as the second distributor distribution loss project is often taken.value3.5dB,4distributor loss oftenvalue8dB; mutual isolation: mutual isolation is also called distribution isolation. If a signal is added to one of the output terminals of the distributor, the difference between the signal level and the signal level of the other output terminals is isolated from each other, and the isolation of the output terminal of the distributor is generally required to be large.on20dBabove. The greater the isolation of the output of the distributor, the better, it means that the mutual influence and interference between the outputs of the distributor are small; standing wave ratio: standing wave ratio is an important indicator to measure the transmission quality of the distribution network, which indicates the degree of impedance matching. Ideally, the input impedance and output impedance of the distributor are exactly equal to the impedance of the coaxial cable to which it is connected, and the standing wave ratio at this timeis1, in fact, the standing wave ratio is often large.on1. If the standing wave ratio is too large, the transmission signal will be reflected at the input or output of the distributor, which will adversely affect the image quality, such as ghosting, etc..distributors are also divided into over-electricity distributors, outdoor distributors, indoor distributors, etc.
101, mono
a sound channel, a microphone is used to pick up sound, and a speaker is used to play sound, which is called mono. In TV broadcasting, the quality of mono sound is not good, especially when encountering advantageous literary and artistic programs, especially when broadcasting high-level music performances live. In addition, mono sound can only be broadcast in one language, which is not applicable to a multi-ethnic and multi-dialect China. It should be developed into double sound (dual channels) to play two languages at the same time, and it also creates conditions for stereo broadcasting..102, double companionsound/stereo
the use of two channels can realize two-channel TV accompaniment, and play the accompaniment of two different languages at the same time, such as using standard Mandarin on the one way; The other uses the local national language or dialect, and the two can be selected at will. You can also use standard Mandarin or national language along the way; use a certain foreign language along the other way, and the two can also be switched at will. For example, when playing the original foreign TV film, although Chinese subtitles can be typed on the TV screen, it always doesn't look smooth, and double accompaniment can overcome the defect of subtitles..dual channels have created conditions for stereo broadcasting. Because human ears can distinguish the distance and direction of each sound source, listening has a sense of space (or three-dimensional sense). In the sound reproduction system, two or more sound channels are used to make the relative spatial position of the sound source felt by the listener close to the relative spatial position of the actual sound source. This kind of playback sound is called stereo sound. Stereo has two-channel stereo, four-channel stereo, Dolby stereo, Dolby surround sound, DuratioAC-3digital surround sound, etc.radio broadcasts using stereo technology are called stereo broadcasts. Take two-channel stereo broadcasting as an example. Two-channel stereo broadcasting is to broadcast two sound signals corresponding to the left front and right front two directions of the listener through one or two broadcast channels of different frequencies. Listeners use a stereo radio with a two-channel playback system to receive, which can distinguish the relative position of the sound source and produce a stereo sense; if you use an ordinary radio, you can also receive the same program content, but there is no stereo sense. In order to meet mono compatibility, most of them use pilot-based FM stereo broadcasting. It uses only one FM radio channel and uses modulated basic sound frequency.rate?quot;Add leftRight"signal, subcarrier amplitude modulation band and pilotdelivery"Subtract from leftRight"signal.In theory, in order to obtain the best stereo sound effect, the ideal method is to use an infinite number of microphones to pick up the sound signal, and then use an infinite number of sound channels to transmit the sound to an infinite number of speakers and replay it. As long as the position of the speaker and the position of the microphone correspond one-to-one, the reproduced sound can accurately reproduce the sound of the scene, so that the audience has the three-dimensional impression of the scene.
103, surround sound
surround sound refers to the replay method in which direct sound and reflected sound surround the listener. Therefore, the more speakers, the stronger the listener feels surrounded. Two-channel stereo can only distinguish the relative position of the sound source. The four-channel stereo system uses four microphones and four speakers. Two of the four microphones are close to the stage to pick up the direct signal of the stage, and the other two are far away from the stage to pick up the reverberation signal reflecting the ambient sound effect. The signals picked up by the four microphones are transmitted to the four speakers by four independent sound channels. Corresponding to the position of the microphone, the speakers are front left, front right, rear left, and rear right; the front left and front right are used to replay the direct sound of the stage, and the rear left and rear right are used to replay the reverberant sound reflecting the environmental effect. The listener was awakened by the flying midge banana.EsoleCalling Perch, Razor, Suspected Xin Li 「schoolslantspringbilgecoreacylBopingbrownscreen(8)?br> 106, DuratioAC-3digital surround sound
AC-3technology originated from high definition(HDTV) to provide high quality sound.AC-3technology is developed by DuratioAC-1, DuratioAC-2.AC-14-2-4the multi-channel matrix method to reduce the number of channels by half (this can reduce the transmission capacity), and then use incremental modulation(modulation) technology for digital coding. Therefore,AC-1is a compression multiple of twice. With sound coding technology and digital signal processors(DSP) progress,AC-1System Developed into Transform-based Coding TechnologyAC-2system, while improving the quality, the compression ratio is further changed.is4times, but the multi-channel matrix processing technology is still retained..AC-3isinAC-1,AC-2, it inheritedAC-2, such as window processing, transform coding, adaptive bit allocation, etc., can also overcome their shortcomings and limitations..AC-3toolhave5.1Channel: left, middle, right, left, and right.and0.1low-effect sound channels, the left and right surround channels here are independent channels made separately, which have a sense of scene and reality. In DuratioAC-3technology, at presenthave6.1channel,7.1channel digital return system.AC-3is beautycountryHDTV's sound system, which has been recognized worldwide.Annotation:4-2-4means that four-channel recording is used for recording. When the recording is placed on the film,will4channel is compressed by encoding technology to cause two channels, which are still heavy when the sound is restored.release4the original sound of the sound.
107, panda accompaniment(PANDA-1)
beautycountryWegenerCommunications Companyon80s, a set of practical TV audio high-fidelity multi-channel multi-language audio demodulation circuit technology was designed, and this technology was namedis"PANDA-1"translation"bearcat-1"high-fidelity multilingual stereo sound), and has obtained a technology patent in the United States. This sound technology is an analog noise suppression system, the function is to put a normal sound, generally must280KHzhigh frequency bandwidth, and it uses half of the high frequency bandwidth130KHz, to transmit the baseband audio message15KHzThe bandwidth. Compress the dynamic range of the sound signal at a specific ratio of several tens of times to a very narrow bandwidth. In this way, each set of image programs can provide up to six audio channels at the same time for stereo or bilingual broadcasting, and can transmit independent radio programs at the same time, that is, three sets of stereo or six mono channels can be transmitted on different frequencies..PANDA-1the sound is used in analog channels, and it is also analog compression, so the sound quality is quite different from the digital sound signals currently used, but due to the saving of bandwidth, there are several more channels. Pick upPANDA-1sound requires the receiver to have an extended circuit audio carrier demodulator, otherwise the received sound is a high noise and high distortion sound. Every toolhavePANDA-1demodulation function can listen to six accompanying sounds or two-channel stereo sound at will, and receive audio programming through remote control operation, screen display and audio programming.
108, Liyin(NICAM)NICAMis quasi-instantaneous companding sound multiplexing, is a digital sound processing technology, the main features are high signal-to-noise ratio, wide dynamic range, sound qualityCDis comparable, hence the name Liyin, becausethisNICAMis also known as Liyin, Liyin is the common name for the digitization of radio and television accompaniment..in China's terrestrial broadcasting and satellite broadcasting, TV accompaniment adopts FM mode. Liyin adds a digital sound sub-carrier frequency to the original sound sub-carrier frequency. The sound forms a dual carrier mode and does not interfere with the original mono signal. MiningAM-FM,FM-FMThe playback mode. The sound mode has stereo mode, that is, the left and right channels; the dual voice mode transmits two kinds of voices from the left and right channels at the same time, and can also transmit two mono broadcasts, or one mono broadcast and one data. During transmission, a special modulator is used to process it and then transmit it together with TV image signals and analog sound signals. When receiving, you can listen after processing with a dedicated sound demodulator.andCDcomparable digital stereo audio programs.International Liyin Systemhave20kinds, China's miningNICAM,DLiyin system. On the basis of retaining the original analog FM sound sub-carrier frequency, a second sub-carrier is added.frequency7.28MHz, using quasi-instantaneous companding coding technology. At present, China's CCTV first and second program satellite transmission system,NICAM-728method inserts the Central 1. Central Two and Central Three Stereo Three Central People's Broadcasting Station programs. When receiving a satellite digital sound broadcast signal, the satellite receiver needs to have a baseband output to connect it.NICAM-728the receiver, after it receives stereo signals, etc., it can easily obtain a high-quality CCTV broadcast program signal source. Terrestrial TV stations transmit sound signals, marking the entry of TV accompaniment into the era of digital stereo. At present, some TV setshaveNICAMThe reception function, but the standard is consistent to receive the sound. Otherwise, you cannot listen to it. You need to distinguish whether it meets the Chinese sound standard.
113, solar cells
solar cell is abbreviated as solar cell. It is a device that uses the photoelectric effect of semiconductor silicon to directly convert solar energy into electrical energy. Solar energy in the earth's cosmic space,every1m2have1.4kw/m2, sunny, on the groundevery1 m2have1 kw/m2. Most of the solar cells used on satellites are silicon single crystals, and solar energy is converted into electrical energy. In theory, the photoelectric conversion efficiency can beda25%, actually not more16%, generalis10%-13%. In recent years, a gallium arsenide single crystal element with high conversion efficiency, high temperature working characteristics and excellent radiation resistance is often used..now have many small pieces of silicon solar cells in series and parallel to form an array. The size of a solar cellis2 × 2cm2,2 × 4cm2and4 × 4cm2, etc., its thicknessis0.15~0.4mm. The number of series cells in a solar cell array depends on the requirements of the output voltage, while the number of parallel cells depends on the requirements of the output current. The total number of chips combined between the two determines its output power..such as Japan's broadcasting satellite(BS-2) uses largeabout11000block silicon solar cell.solar cells is not all used directly, but part of it is stored in the battery in the satellite. When the satellite is in the shadow area of the earth and the solar cell does not generate electricity, the battery supplies power to each part of the equipment to work..silicon solar cells are currently the main force in space cells,accounts80% will also occupy a major position in future applications, so it is very important to improve the efficiency of silicon solar cells. The utilization of gallium arsenide solar cells is also gradually improving. These two solar cells will be the main force of space energy..114,Fast star change technologyfor a long time, Asiacontinent2(100.5 °E)ETTVfree dinner has become a hot spot for most satellite TV fans. During the Spring Festival, some people said that it would be encrypted and straight.7month10that the broadcast was truly suspended, leaving only Beijing, Tianjin, Hebei and Shan.West4set of programs, all the TV fever friends are busy changing stars. Pull the power cord, move the receiver and monitor, everything can't be less. Compared with the initial installation, only a few holes can be drilled. Who is willing to run up and down the balcony on the top of the building in the scorching sun, and be busy. No matter how skilled you are, your proficiency will make you sweat profusely. If it is OK to install one, there are still a lot of friends waiting for you.!, I will introduce the skills of fast star adjustment to everyone so that the vast number of satellite TV fans can enjoy it together. Now I will introduce Asiacontinent2100.5 °ESatellite for Asiacontinent2R 76.5 °Esatellite to do a demonstration.Take Wenzhou, Zhejiang Province as an Example: Urban Weftdegree28, Eastsutra120.7, Asiacontinent2angleA38tiltangleE50.46, Asiatoo2R. bearingangleA64.18tiltangleE31.94. (Please refer to "Satellite TV Weekmagazine1999Star Search Manual)The basic steps are as follows:1,turn on the TV and satellite receiver, and the reception of Beijing station is normal. (No means that there is a problem in some part of the system and must be checked again.)Press the key to the main menu,presskey, move the cursor to the program to increase or adjust the antenna, (depending on the model) if the same continent machine canpresskey to directly display the program search menu.After entering the program addition menu, the downlink frequency is changed from the original12329change12530The symbol rate is changed from the original06930change30000polarization is changed to horizontal (depending on the installation of your original high-frequency head). Now leave one person in the room to observe. At this time, you can go to the top of the building..2,with one10-12ring wrench, normal measuring angle1only (stationery store hassale1yuanmoney1only, there is a small hole in the middle, which can be threaded into a knot, and a nut is tied to the other end) handmachine1.3,first calculate the degree of elevation, sub-continent2Wenzhouarea50.46-Asiacontinent2R 31.94=18.52, because many antenna manufacturers are different, the accuracy is also different, no matter how much antenna deviation, you first put the protractor to the high frequency head pole and immediately read how many degrees (see Figure 1). Asiacontinent2elevation angleis50.46, now you add it according to the actual measured degree.18.52. For example,50.46 18.52=68.98, then loosen the left and right two elevation adjustment screws, straight68.98degrees (see fig. 2), and then loosen the azimuth fixing screw to the west.20degrees, use your mobile phone to connect the indoor phone, and then slowly turn to the west a little bit. The indoor signal will appear immediately.QPSK Eb/Nois locked when the maximum is reached. (For example, at night, the brightness of the mobile phone display screen can be used to help read the protractor without borrowing lights).I only use the fastest star change2points50seconds. After completing the preceding tasks, you can enter other frequencies in the room. (12278V 22425,12308V 224525,12650V 30000,12405V 30000,12629 H 30000,12374V 05660), of course, is not a problem, if you use this method to calculate for other satellites is also very convenient.

AC (Alternating Current)communication
ACI (Adjacent Channel Interference)adjacent frequency interference
ACU (Antenna Control Unit)antenna controller
A/D (Analog to Digital Conversion)analog-to-digital conversion
AFC (Automatic Frequency Control)automatic frequency controlsystemAFT (Automatic Frequency Tune)automatic frequency tuning
AGC (Automatic Gain Control)automatic gain control
AM (Amplitude Modulation)amplitude modulation
Amplifieramplifier
Antennaantenna
Antenna Direction Controlantenna pointing control
ATV (The U.S Advanced Television System)America's Advanced TV System
Audiosound
Bandwidthbandwidth
BDC (Block Down Converter)downconverter
bit streambitstream
Brightbrightness
Broadcastbroadcasting
BS (Broadcasting Satellite)radio guardstar(day) CC/Ku-Band Compatible C/Kuband compatibility
lamperclamp circuit
Colorcolor
CATV (Cable Television or Community Antenna Television)cable TV system or common antenna system
Color Frequency Convertercolor subcarrier converter
Color Sub-carriercolor subcarrier
Communicationcommunication
Community ReceptionCollective reception
Composite VideoComposite Video Letterit includes synchronization signal, chrominance signal and brightness signal
CP (Circular Polarization)circular polarization
D/A (Digital to Analog Conversion)digital-to-analog conversion
DAB (Digital Audio Broadcasting)digital audio broadcasting
DAC (Digital/Analog Conversion)digital-to-analog conversiondataData
dBdecibels
dBiAntennabenefit(relative to isotropic radiationsource)
dBWdecibelstilerelativeon1WpowerdBvalue
DC (Direct Current)DC
DCT (Discrete Cosine Transform)discrete cosine transform
DE (De-emphasis)to aggravate
Decoderdecoder
Digital Standards Converterdigital converter
Dishdish antenna
DSM (Digital Storage Media)digital storage or transmitterpiecesDTH (Direct-to-Home)Satellite TV LiveDVB (Digital Video Broadcasting)digital television broadcasting
EDTV (Enhanced definition Television)Enhanced Definition TV
encoderencoder
Equalizationequilibrium
Equalizationequilibrium
Filterfilter
Frequencyfrequency
FeeddeliveryTV Signal
FSS (Fixed Satellite Service)Fixed Satellite Service

FPLL (Frequency and Phase Locked Loop)frequency and phase locked loop
Geo-stationary Satellitegeostationary satellite
HDTV (High Definition Television)high definition electricityHeadendCable TV Front End
Hemispheric Beamhemisphere beam
Horizontal linear Polarizationhorizontal linear polarization
IF (Intermediate Frequency)intermediate frequency
Integrated Circuitintegrated circuit
Interferenceinterference
Intermodulationintermodulation
IR (Infrared Remote Control)infrared remote control
Knobknob
Latitudelatitude
LHCP or LCP (Left-Hand Circular Polarization)left-handed polarization
Limiting Amplifierlimiting amplifier
Limiting FigureLimiting system
Linkline
L.O. (Local Oscillator)local oscillator frequency
Longitudelongitude
Lossloss
Luminancethe brightness of the video signal
ManulManual
Modulatormodulator
MENUParameter Settings menu
Motorelectric
MDCT (Modified Discrete Cosine Transform)Changes
NorthNorth
OFFDisconnect
Output Impedanceoutput impedance
Onon
Orbitorbit
Oscillatoroscillator
Phasephase
Pictureimage
PLL (Phase-Locked Loop)phase locked loop
PM (Phase modulation)phase modulation
Point Beamspot beam
Polarizationpolarization
Powerelectricitysourcepower
Prime Focus AntennaForward fed antenna
Programprogram
Programmable Channelprogrammable channel
Receiverreceiver
RHCP or RCP (Right-Hand Circular Polarization)Right-handed park polarization
RF (Radio Frequency)High frequency, radio frequency
Shaped Beamshape(endowmentshape)beam
Signalsignal
Skewtwist, offset, and tilt
SMATV (Satellite Master Antenna Television)Satellite Shared Antenna TV System
SR (Symbol Rate)
STB (Set-Top Box)Set Top Box
Stereostereo
Switchswitch
TerminalTerminal equipment
Thresholdthreshold
Transmittertransmitter
Tunetuning
Tunerchannel tuner
TVBS (TV Broadcast by Satellite)satellite televisionbroadcastTVRO (Television Receive Only Terminal)Satellite TV Ground Receiving Station
U/C (Up Converter)upconverter
VSAT (Very Small Aperture Terminal)Very Small Aperture Satellite Ground Station
VSWR (Voltage Standing Wave Ratio)voltage standing waveratioVertical Linear Polarizationvertical linear polarization
VOD (Video on demand)ApsaraVideo VOD
Withstand Windwind resistance
Waveradio waves
WestWest
X-bandXwave8/7GHz
Zone Beamarea beam

()

img1


Created on:2022年4月9日 22:40
PV:0
Collect