Broadcast means throughradio wavesorwirewaySound transmittingNews communicationTools.Scale for transmitting programs by radio wavesair cast, program transmission scale through wirecablecast。The advantages of broadcasting are wide range of objects, rapid spread, diverse functions and strong appeal;Disadvantages are fleeting, sequential listening, no choice, and difficult listening if language is not available.
Chinese name
radio broadcast
Foreign name
Radio broadcasting；Broadcast；Be on the air；Airing
Pinyin
guǎng bō
Cantonese pronunciation
gwong2bo3
Advantages
Wide range of objects, rapid spread, diverse functions, etc
Broadcasting is the most common form of multi-point deliveryDestinationDeliveryA copy of a group.It can be completed by delivering multiple single packets, or it can deliver copies of packets through separate connections until each receiver receives a copy.
On Christmas Eve in 1906, Fresendon and Alexandrson of the United States set up abroadcasting station, and broadcast for the first time ever.The content of the broadcast is two jokes, a song and aviolinsoloQu.This radio program was widely held at that timeReceiverWe heard it clearly.
In 1908, American Forrest was in Paris againEiffel TowerA radio broadcast was conducted on theMarseilleAn engineer of.
In 1916, Forrester broadcast the news aboutpresidential electionAt that time, only a few people could listen to these early broadcasts.
Real radio was born in the 1920s.
The first licensedradio station, is the United StatesPittsburghKDKA radio station, officially launched on November 2, 1920.
The first radio station in China was founded in January 1923 by Osborne in the United States. It belongs to Chinaradio broadcastThe company's radio station was first broadcast in Shanghai.
In 1926, the first self run radio station appeared in China - Harbin Radio StationLiu Hanestablish.
The advantages of broadcasting are wide range of objects, rapid spread, diverse functions and strong appeal;The disadvantage is that it is fleeting. You can listen in order, but you can't choose. If you don't know the language, it is difficult to listen.(The right picture shows the United States in 1919Marconi6.5 kW radiotransmitter）
radio broadcast
development
Due to the wide use of radio and people's concern for high-power transmitters and high sensitivityElectronic tubeThe mastery of receiver skills has gradually made broadcasting a reality.
In 1919, the Soviet Union produced a high-power transmitter, and in 1920MoscowStart the pilot broadcast.
On June 15, 1920, Marconi Company held a "radio telephone" concert in Britain, starring Mrs. Melba, as far away as ParisItaly、Norway, even inGreeceCan be heard clearly.This is the beginning of broadcasting.
On November 2, 1920, under the guidance of Conrad, the Westinghouse radio station KDKA began broadcasting. The first program broadcast was the Harding Cox presidential election. At that time, it was a sensation.
On December 22, 1920, German radio station Konewosthausen broadcast an instrumental concert for the first time.
On November 14, 1922, London's ZLO radio station officially began to broadcast daily programs in the UK. In 1927, the station was changed into the British Broadcasting Corporation Limited, namelyBBC。
1922 FranceEiffel TowerIt also officially started broadcasting.
By 1927, there were 737 radio stations in the United States.
During this period, radio stations mushroomed in various countries.At that time, broadcasting in Europe was regarded as a huge communication tool.Since then, the broadcasting industry around the world has continued to develop and has gradually formed a global broadcasting network.
In 2011, mobile radio entered the audience's vision.
In 2019, mobile broadcasting market,HimalayanFM andDragonfly FMFormedduopoly The situation is far ahead of other platforms in the industry.Himalayan FM had the largest user increase last year, with 400 million users worldwideMobile radioThe industry is inLeaderStatus;Dragonfly FM ranked second with an increase of 113.03 million.litchiFM has also found its own position after transformation, and has firmly established itself as the "third brother" in the industry.Phoenix FMPremium listening station、Still listening to FM、Cool FMThen it ranks behind and in the third echelon.[1]
Listening mode
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Terminal reception
adoptradioetc.terminal equipmentReceive signals to listen to the radio, but only a limited number of channels can be heard.
Listen online
Nowadays, many radio stations provide Internet listening services. Many websites collect the listening addresses of these radio stations. Users can listen to radio programs online through the Internet.
Related enterprises
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Jiangsu Broadcasting Group
according to the investigationJiangsuprovinceRadio and Television GroupIn the first half of the year, the Group achieved a revenue of 5.624 billion yuan, an increase of 1.368 billion yuan or 32.2% year on year.
radio broadcasttelevision advertisingAmount of money receivedYear on year growth17.22%, of which,Jiangsu Satellite TVThe amount of money received increased by 19.43% year on year, and the happiness education company increased by 63.38% year on year.The emerging business forms are steadily advancing.The revenue of new media business increased 35.6% year on year.
According to the survey of China Film Group, the group opened 6 new cinemas in the first half of the year, with 44 screens,Number of seats7469.As of the first half of the year, China Film Holding had 55 cinemas, 361 screens and 59040 seats.
According to preliminary statistics,ZhongyingJoint stock company in the first half of 2012business income2.06 billion yuan, a year-on-year increase of 800 million yuan, with a growth rate of 79.27%, much higher than that of the whole countrybox office 41%Growth rate, overallTotal profit realized514 million yuan, an increase of 120.01% over the same period in 2011.
Private car radio
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Broadcast frequencySpecialization has become the trend of the development of city radio stations, and the functional subdivision of professional radio stations is an inevitable trendAuto AgeThe arrival ofBroadcast mediaThe inevitable trend of development.However, from the current situation of private car radio, it is more like a“ragtag troops”"The weakness of all inclusive and loose content gradually revealed".Therefore, there are still a lot of private car radioExplore space, mature and clearly positioned private car radio needs to be explored and honed.The following is the author's vision for the development of private car radio.
It is undeniable that there are intersections and conflicts between traffic radio and private car radio in the fields of audience, program, information, service, etc., because both of them serve the mobile population and take cars as carriers.
However, as a result of further specialization and narrowcasting of radio stations, private car radioRadio positioningThe positioning with the audience is more concrete and clear.Therefore, if you want to seek your own space in the era of traffic broadcasting, you shouldAudience Targeting , program content, personality characteristics and other aspects to reduce the traffic broadcastHomogenizationTo provide private car owners with high-end and considerate services, so as to meet their requirements and make distinctive and unique positioning.At the same time, according to private car ownersPeak hourThe program is more detailed, and accurately grasp the private owners'Life philosophyAnd the rhythm of life, reasonably divide the types of programs, and timely and appropriately provide services in consultation, road conditions, music, life and other aspects.
（2） Find out what resonates with the audience.
"The family listening mode of radio in the era of private cars means two more significant changes: one is to create a rare family members to gather in aEnclosed spaceThe second is that the proportion of female listeners has greatly increased. "Therefore, private car radio can take the information concerned by family life as one of its own characteristics, and focus on reflecting the concerns of a family, such as housing pricesoil priceOr children's education.Through these detailed and specific program contentsBy familyOur audience provides thoughtful and fragmented services so that family members can continue to pay attention to private car radio during listening and discussion, thus stabilizing the listening characteristics of private car radio.
With the advent of the era of private cars, more and more women begin to masterSteering wheel, in sharp contrast to the situation where professional drivers are mostly men.Therefore, private car radio can be considered from the perspective of female private car owners, and women's topics and content can be appropriately increased, so as to increase women's private car audience's awareness of private car radioloyaltyAnd expectations.
In addition, most of the audience of private car radio are professionals, while urban people's depression on the way to and from work is often not vented.according toSocial Investigation Center of China Youth DailyA survey of 2750 people shows that 83.1% of white-collar respondents admit that they have different degrees of“Silence after work”。Therefore, the private car radio should pay attention to the audience's desire to vent, find the resonance between the radio and the private car owners, and relieve the pressure and relax the mood of the audience.
（3） Ensure program quality and stabilitybrand effect。
"The audience characteristics of private car radio are very obvious: first, the audience of this kind of radio is highly educated and informativeconsumer demandBig, yessocial cultureThe leader and major consumers of;SecondConsumption capacityStrong, centeredHigh end consumer goodsMore attention, more involvement and more ownership. "Private car owners usually pursue a higher level of life, and this part of the audience pays attention to the quality of life.Therefore, private car radio should meet the quality requirements of private car owners and audiencePsychological needs, we should use the best broadcasting frequencyOffline activitiesMore and more, it has become another business channel for radio stations.The private car radio is aimed at the middle and high-end private car owners, supported by the automobile industry, and has enough space and strength to establish a brand and form a brand effect.Therefore, compared withRelated industriesClose linkage is conducive to forming the unique brand effect of private car radio.
Transmission principle
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schematic diagram
Radio stations broadcast programs by first converting sound into audio through microphoneselectrical signal, amplified byHigh frequency signal(carrier) modulationcarrier signalA parameter ofsound signalMake corresponding changes so that the audio signal we want to transmit is included in the high-frequency carrier signal. The high-frequency signal is amplified, and thenhigh-frequency currentFlow throughantennaWhen, formradio wavesOutward emissionpropagation velocityIt is 3 × 10 ^ 8m/s. This radio wave is received by the radio antenna, and then amplified, demodulated, restored to audio electrical signal, and sent to the loudspeakervoice coilMedium, causingPaper basinThe corresponding vibration can restore the sound, that is, the process of acoustoelectric conversion transmission electroacoustic conversion.
The high-frequency signal received by the antenna passes throughInput circuitLocal unit with radiooscillation frequency (Its frequency is one fixed intermediate frequency higher than that of foreign high-frequency signals, and the intermediate frequency standard in China is 465KHZ) sent into the frequency conversion tube together for mixing——frequency conversionWhen a new frequency is generated in the load circuit (frequency selection) of the frequency conversion stage, it passesDifferential frequencyThe generated IF (B in Fig. 3-2) only changes the carrier frequency, but the original audio envelope does not change,IF signalIt can be amplified better. The IF signal is detected and the high-frequency signal is filtered (D in Fig. 3-2).After low amplifier and power amplificationspeakerMake a sound.
VT4 and VT5 are front low-frequency amplification stages, and VT6 and VT7 constitute Class BPush-pull power amplifier。R16, C21 and C17 are power wave circuits.R1、R2、R3、R4、R5、R6、R7、R12R10, R11, R13, R17 and R18 are DC of all levelsbias resistor 。
install
① Complete machine circuit analysis, familiar with components inPrinted boardUpper mounting position.
② Welding and installation of components (check the quality of components during installation).
③ Check the circuit. Check the following contents by comparing the installed radio with the circuit schematic diagram.
a. Check all levelstransistorWhether the model, installation position and pin of are correct.
b. Check all levelsMid weekInstallation sequence ofOutgoing lineWhether it is correct.
c. CheckElectrolytic capacitorWhether the positive and negative connection methods of the lead wires are correct.
d. Piecewise woundMagnetic antennaWhether the primary installation position of the coil is correct.
e. UsePointer multimeterMeasure the resistance of the whole machine with gear R × 100. Connect the red probe to the negative wire of the power supply and the black probe to the positive wire of the power supply. The measured resistance of the whole machine should be greater than 500 Ω.
The 4.5V power supply can be connected only after the above checks are correct.
① AdjustmentStatic working point: The functions of each transistor are different, and the operating points are different. The adjustment of static operating points at all levels is through each transistor when there is no signal (local oscillation and vibration stop) when there is no external signalEmitterThe voltage on the resistance is measured separately.Gradually adjust R1, R4, R12, R17 and R18 to make VT1 voltage - 0.5~0.7V.Voltage on VT2 level R6 is - 0.5~0.7V.Voltage on VT3 level R7 is -0.25~0.4V, VT5 levelR14The voltage is - 0.7~0.9V, and the current of VT6 and VT7 is 2~6mA.
② Adjust IF: the purpose is to make threeMid cycle transformer(IF tuning circuit)resonant frequency It is adjusted to a fixed intermediate frequency of 465KHZ. Since the used intermediate frequency is new, the manufacturer has generally adjusted it to 465KHZ, so during commissioning, a certainradio station, use without feelingScrewdriverAdjust the magnetic core of the middle cycle, and the adjustment sequence is from the rear stage to the front stage, that is, first adjust Bz3 and then Bz2 to the hornvoiceUntil the loudest.
③ FM rate coverage (the frequency range of the tuner is 535-1605kHz): the last one when adjustingDial, makeDouble connected variable capacitorwholePrecessionRotate the double connected variable capacitor to align the pointer with the 640 kilocycle scale（Central People's Broadcasting Station）Rotate with non sensing driverOscillating coilThe 640 kilocycle radio broadcast is listened to by the magnetic core, and the sound is moderate. Rotate the double variable capacitor to align the pointer near the 1500 kilocycle scale.adjustmentOscillation loopThe trimming capacitor C3 listens to the radio broadcast near 1500 kilocycles, and the high-end and low-end are repeatedly adjusted for several times.
④Unified modulation(Adjust frequency tracking) The purpose is to make the local oscillation frequency within the receiving frequency range (middle band 535 ～ 1650kHz) and far more exoticsignal frequency High 465KHz means that the oscillation frequency range of the machine is 1000kHz~2070kHz.Therefore, C1 and C2 double connected variable capacitors with the same capacitance are used for synchronous adjustment, and tracking is usually carried out at the high, middle and low points within the selected frequency range, that is, three-point unified tuning. In order to achieve good three-point tracking, an adjustment capacitor C is connected in series in the local oscillation circuit, a micro adjustment compensation capacitor C is connected in parallel, and a compensation is connected in parallel in the input circuitTrimming capacitorC，Specific adjustment, and then adjust the input circuit compensation capacitor Cz to make the loudest volume.
The middle end is adjusted to listen to the radio near 1000KHZ to make the loudest sound. At this time, adjust the C piece on the flower piece in the moving piece of the double connected capacitor, and move the distance between pieces.If the input decreases when the pattern is moved, the middle end will not be out of tune and the pattern will be moved backoriginal placeIf the input increases, it is also necessary to move the matching lace to compensate, and the capacity of the padding capacitor can also be changed.
According to different uses, the area of the studio can be divided into 15~80 square meters.Language studioThe area is generally less than 30 square meters, and the reverberation time is 0.4~0.5 seconds.The art studio has a large area, and different areas and different reverberation times are designed according to the number of actors and the nature of the program.UsingMultichannelRecording post processing technologystudioIn order to increase the separation capacity between each sound channel and reserve the space for post processing, it is required to set up strong sound absorption and diffusion facilities.The reverberation time is controlled within 0.5~1s, which has nothing to do with the number of actors and the nature of the program.
With longerreverberation time andDiffuse sound fieldA special room for recording.In the process of recording or recording reproduction, in order to improveSound effectThe reverberation room needs to be used to artificially add reverberation or create echo in the sound.The reverberation time shall be 3-5 seconds or longer.Reverberation room soundDiffusivitySound insulation and vibration isolation shall be properly conducted.Activities can be set indoorsSound-absorbing structureTo change the reverberation time.
Broadcast level
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Radio station
Broadcasting is divided into layer 2 broadcasting and layer 3 broadcasting.
Layer 2 broadcasting, also known as hardware broadcasting, is used inLANSend data to all nodes, usually not across the LAN boundary（Router）, unless it becomes aunicast。The broadcast destination address is a binary all 1 orhexadecimalAll FIP address（255.255.255.255）。
Broadcast (Layer 3) is used to send data to all nodes in this network.Layer 3 radio also supports the old flat radio.Broadcast information refers to a message thatBroadcast domainInformation for all hosts.These are calledWebcast, all host bits are ON.
OneData frameOr the packet is transferred locallyNetwork segmentEach node on (defined by the broadcast domain) is broadcast;becauseNetwork topologyThe design and connection problems of, or other reasons lead to a large number of copies of broadcast in the network segment, the propagation of data frames, resulting in network performance degradation, or evenNetwork paralysis。This is it.Broadcast storm。
In fact, most broadcast storms occur in the LAN connected by hub, which is easy to generate ring connections. If routers and switches are used, they can effectively prevent broadcast storms because they are tree connected.
But inBackbone networkRouters are mainly used for routing.The router on the backbone network must know the path to all the underlying networks.This requires maintaining a hugeRouting tableAnd respond as quickly as possible to changes in connection status.Router failure will lead to seriousinformation transmissionQuestion.stayCampus networkInternally, routers are mainly used to separateSubnet。along withnetwork size With the continuous expansion of, the LAN has evolved into a multi subnet composed of high-speed backbone and routerCampus network。Each subnet is logically independent, and the router is the only device that can separate them. It is responsible for packet forwarding and broadcast isolation between subnets, and the router on the border is responsible for connection with the upper network.
Radio development
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radio broadcast
In 1895, Marconi andRussiaPopov also invented radio waves.
On March 28, 1899, Marconi successfully sent the first lettertelegraph(England to France).
Vanston'sMassachusettsFirst broadcast of experimental radio station, from broadcasting projecttechnical standardLook, radio was born.It was originally an entertainment tool.
August 31, 1920, United StatesDetroit8M experimental platform broadcastMichiganLong preliminary win news.(The earliestradio news）
On October 27, 1920, the KDKA radio station in Pittsburgh was officially established, which is legalmanagement rightThe first radio station of.Its broadcasting marks the official birth of broadcasting.
On January 24, 1923, the first US radio station in China was officially launched, with the call sign of ECO. It was the first radio station in China.
On December 30, 1940, Yan'an Xinhua Radio Station started broadcasting with the call sign XNCR.The first radio station founded by the Communist Party of China.
On October 28, 2020,Voice of the Yangtze River Delta of Shanghai People's Broadcasting StationIt was the first regional radio broadcast by a local radio station in China.Newly launchedChangjiang deltaVoice will build a new communication platformmainstream mediaExpanding the territory of mainstream value influence ", committed to becoming an important media force and cross regional media cooperation platform in the process of high-quality integrated development of the Yangtze River Delta.[2]
Broadcast advantages
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Auditory information
radio broadcast
Broadcasting is spread by sound.The charm of sound lies in that it not only spreads information, but also integrates these information into the knowledge of the communicator, so as to help and guide people to understand and accept information.hostThe style of hosting the program and the grasp of the program can greatly enhance the attraction of the program.Their re creation and re improvement of manuscripts can have a great impact on the audience's understanding, understanding and acceptance of information.
With sound as the communication feature, its charm also lies in that radio is suitable for all regardless of the audience's age and education level.Radio can alsomobilityAnd portability.People can easily learn the latest information from the radio at any time, anywhere.
Cost economy
Whether it is its own operating cost or the audience's receiving cost, the various costs of broadcasting are the lowest and most economical.
From the perspective of the audience, broadcasting is the acquisition ofInformation priceThe cheapest media.This is related to peopleConsumption levelIt doesn't matter if the consumption level is higher, because people want to get the maximum return with the least investment.Now and in the future, due to various conditions, not all families can own computers, nor can all people own computers in all occasions. It is easy to buy a small semiconductor or use other means to listen to the radio.
From the perspective of the communicator, the cost of the interview, production, transmission and other links of radio programs is lower than that of other media.For example, a telephone can solve the problem of interview and transmission of radio programs,E-mailIt is also increasingly used by radio reporters for interviews.These means, althoughCan't replaceFace to face interview, but in some cases, it saves valuable time and improveswork efficiencyIt also reduces the consumption of human, material and financial resources caused by long-distance program acquisition.Of course, these methods can also be used by other media, but what radio gets from these methods is uniqueExpression——Sound.
Fast
Broadcasting mode
First of all, the broadcasting speed is fast.Speed is a major advantage of the network. For general information processing, the Internet is faster than broadcasting.However, for major events and news, broadcasting is faster than the Internet.In other words, what is watched by radio reportersNews communicationThe speed can be almost equal to the progress speed of the event.
Mobile phoneThe popularity of radio programs has greatly improved theTimeliness。At the scene of the news event, the radio reporter only needs to have a telephonebe all eyes and all ears, while observing, interviewing, thinking and broadcasting orally, send the signal directly to the live broadcast room, and report the progress of news events to the audience in real time;At the same time, it can also make all kinds of sound on the scene, such as the conversation of characters and natural sound, go directly to heaven.The radio can also be broadcast live, from which the audience can learn the progress of news events in real time.
Broadcasting disadvantage
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1. Poor retention.communication effect It is fleeting, and the information is hard to query and record due to poor storage.
2. Poor selectivity.LinearCommunication mode, that is, pressChronological orderIn order, the audience can only passively accept the established content due to the restrictions of the program sequence.
3. The broadcast has only sound, no words and images, and the audience's attention to the broadcast information is easily distracted.
Webcast
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summary
Webcast is a kind of networkStreaming Media, which runs a specificSoftwareThen spread the program, we cancomputerInstall and run radio receiving software on the to connect these sites, and then you can easily listen to radio programs and read radio information.
advantage
In broadbandnetwork techniqueToday, with rapid changes, it is relatively easy to realize webcasting,equipment investmentRelatively few, with inherent advantages, media from all over the world compete to develop online broadcasting. After a few years of development, according to incomplete statistics, the world is nowInternetThere are more than 3400 video broadcasting websitesRealPlayerThe system has more than 3600 audio broadcast websites;More than 6000 hours of new video/audio programs and more than 2300 hours of on-demand programs are broadcast every week.From the perspective of foreign broadcast content, about 60% of audio/video broadcast websites broadcast single thematic content, and about 40% of audio/video broadcast websites broadcast comprehensive content.In China, GuangdongPearl River Economic RadioOn December 15, 1996, it took the lead in launching online real-time broadcasting.CCTVIn 2001 and 2002Spring Festival GalaAll aboveOnline live broadcast。
mode
Webcast has two main broadcast forms: live broadcast and on-demand broadcast:
A Live: It is mainly used for real-time reporting of major events.It is the online transmission form of actual broadcast programs of radio or television stations. Its advantages are strong timeliness, vivid and practical, and users can obtain information at the first time.
B On demand Audio/Video: on-demand is to make the program into clips according to the content. You can select your favorite clips according to the title or classification to listen and watch.This form of play has the advantage of saving resources, and is more selective and targeted.
Development trend
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In December 2021,General Manager Office of CCTVFormal authorizationYangguang Media Group Co., Ltd(hereinafter referred to as "CCTV Media Group")Car networking systemExclusive operation of broadcast frequency live stream of the main station.This means that the existing radio frequencies owned, controlled and managed by the main station and the frequency access of new radio stations in the futureCar enginePlay service (including live broadcast and delayed listening),All mustVia“Cloud Listening”On board system may cooperate with CCTV Media Group.
"Cloud Listening" is the national 5G sound new media platform launched by China Central Radio and Television Corporation (hereinafter referred to as "the Corporation") in March 2020, and is the only audio client under the Corporation, which carries the broadcasting of the CorporationStrategic transformationThe important mission of integration.
This exclusive operation authorization will have a profound impact on the standardized development of the ICV industry.In the future, only through "Yunsheng" or the Central Media Group can reach a partnership to connect the broadcast frequency live stream of the main station to the Internet of Vehicles system provided by the car brand and the post installed Internet of Vehicles system developed by the post installed product company, which is expected to end the situation of the past Internet of Vehicles radio station being used in wanton infringement, and ensure that car owners enjoy safety standardsContent ServicesEquity.[3]
Overseas development
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Broadcasting has achieved remarkable results in going global.Realize the frequency modulationMedium waveMainlyshortwaveComplementarystrategic target, it's meInternational broadcastingHistoricMajor changes。International RadioIn the United StatesCanada、Libya、CambodiaOther countries have added 8 direct landing projects with full frequency, and 19 overseas full frequency radio stations.It is the first time to land in key cities in the United States.The new landing time is 149 hours a day, and the total landing time reaches 700.5 hours a day.
English broadcasting in New China was born in the war years.For a long time, English in Chinaelectronic media It mainly focuses on the English Channel of China Radio International, which dominates China's foreign broadcasting and becomes an important window for China's foreign communication.By the end of 2010,China Radio InternationalIt can broadcast programs in 61 languages every day for 2471 hours, covering more than 200 worldwidecountries and regions 。In 2010, we received 3 million letters and emails from listeners from 161 countries and regions around the worldaround the world3165 audience clubs.ChinaInternational RadioAt present, it is not only one of the most influential overseas publicity units in China with the largest overseas audience, but also has four indicators of broadcast language, broadcast time, transmission power and audience lettersworldTop international radio stations.
definition
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BroadcastMeansPacketstaycomputer networkWhen transmitting in, the destination address is one of all devices in the networktransmission mode。In fact, the "all equipment" mentioned here is also limited to one scope, which is called“Broadcast domain”。
Not all computer networks support broadcasting, such asX.25Network andFrame relayNeither of them supports broadcasting, and there is no broadcasting "in the whole Internet".IPv6It also does not support broadcasting. The corresponding functions of broadcasting areMulticastReplace.
Generally, broadcasting is limited toLANIn, such asEthernetorToken RingNetwork.Because the impact of broadcasting in LAN is far greater than that inWANMuch smaller.
Broadcast address
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Ethernet andIPv4All networks use all 1 addresses to represent broadcasts, which are respectively ff: ff: ff: ff: ff: ff and 255.255.255.255.
Token Ring Network UsageIEEE 802.2A special value in the control domain represents broadcast.
