The function is linked from the interchange of the channel. Merezhevi technologies, channels, communication and basic characteristics

1. Channel connection

Link channel - system technical assistanceі the middle of the broadening of signals і in transmissions every time (as danikh) from dzherel to won (і navpaki). The channel of the sound, which seems to be at the vuz'kom meaning (the path of the connection), represents only the physical middle of the extended signals, for example, the physical line.

Channel for communication of signal transmission values ​​from distant outbuildings. The signals are the essence of information, designated for the submission of koristuvachev (people), or for the application of the applied programs of the EOM.

2 The communication channel includes the following components:

1) transmission prist_y;

2) prime prist_y;

3) the middle of the transmission of physical physical nature

Signal transmission molding, do not have information when passing through the middle of the gear, go to the entrance to the near annex. The given information is seen from the signal and transmitted to the survivors. It is the physical nature of the signal to vibrate in such a rank that it widens through the middle of transmissions with the smallest weakening and spontaneous. The signal is a necessary carrier of information, but it does not carry information itself. link channel

Tobto. tse (channel) - technical adjustment(technology + middle).

3. Characteristics (parameters) of the channels in the communication

1. Transfer function to the channel: it is supplied at the viewer with the amplitude-frequency characteristic (AFC) and showing, as extinguished, the amplitude of the sinusoid at the input to the channel in proportion to the amplitude at the input for all possible frequencies before The knowledge of the amplitude-frequency characteristics of the real channel allows the form of the input signal to be assigned to any input signal. For this, it is necessary to know the spectrum of the input signal, to reconfigure the amplitude of the warehouse harmonics to the amplitude-frequency characteristics, and then to know the shape of the input signal, by playing the reconfigured harmonics. For an experimental adjustment of the amplitude-frequency characteristic, it is necessary to test the channel with standard (equal in amplitude) sinusoids over the entire frequency range from zero to a maximum value that can be measured at the input signals. Moreover, the change in the frequency of the input sinusoids is required with a small croc, and hence the number of experiments is large.

2. Smuga throughput: є obhidnoy characteristic of the frequency response. Vona є without an interruption in the frequency range, for which the amplitude of the output signal is transmitted to the input signal, the boundary is set in advance, so that the smog is passed through, the frequency range is set to the signal, when the signal is generated, the signal will be transmitted through the channel. Call the smog, the transmission will be deprived at equal 0.7 from the maximum value of the frequency response. The width of the smuga is the least inflow the maximum possible speed of transmission of information by the channel.

3. Decrease: there is no longer any change in the amplitude of the signal if the channel is transmitting to the signal of the singing frequency. Often, when the channel is in operation, the main frequency is the signal to be transmitted, so that the frequency, the harmony of which is the greatest amplitude and pressure. That is enough nobility

zasannya at the ts_y frequency, about an approximate estimate of the signals generated, which are transmitted over the channel. Accurate estimates can be made if the decalcification is known at decile frequencies, so that the decile of the fundamental harmonics is reflected in the signal to be transmitted.

Extinguish is measured in decibels (dB) and calculated according to the following formula:

De Рвх - pulling the signal to the input channel, Рвх - pulling the signal to the input channel.

Zasannya zavzhdi rozrahovuєtsya for the singing frequency and associated with the pre-music channel. For the sake of it, you want to repent of the witnesses "chase fizzled out", tobto. Extinguishing signal to one channel per channel, for example, extinguishing 0.1 dB / meter.

4. Frequency of transmission: characterizes the number of bits, which is transmitted by the channel in one hour. Vona change in bits per second - bit / s, and in old units: Kbit / s, Mb / s, Gbit / s. The speed of transmission is based on the width of the smog through the channel, the level of noise, the type of code and modulation.

5. Transmission of signals to the channel: characterizing the quality of the transmission of signals for the minds. The change was taken on the internal (є heat noise of the apparatus) and call (the stench of good news and to stay in the middle of the transmission). The overshoot of the channel is based on hardware and algorithmic solutions from the processing of the received signal, which is embedded in the reception-transmission attachment. The overshoot of signal transmission through the channel can be adjusted for the function of coding and special processing of the signal.

6. Dynamic range: logarithm of the ratio of the maximum signal pressure, which is passed by the channel, to the minimum.

7. Interference immunity: no interference protection, tobto. schism.

Channels are communication є the main lanka of any transmission system. You can use the classification of channels to use different signs.

Classification of channels

Oscillations are sent to the communication channel without any connection, then the information transmitted will need to be paid by the vigilante, which will be sent to the given channel. Also, a reinvention of the linkage from the signal modulation.

Modulation - change of any parameter to the signal in the channel (modulated to the signal) according to the current values ​​of the data to be transmitted (to the model signal). The gateway to the transformation of the modulated signal into the module is called demodulation. For a wide range of special attachments - modems. The name "modem" is stored in two warehouses: the first warehouse means a modulator - attaching a direct signal), another warehouse - a demodulator - attaching a ringing signal.

The most common modems have the following types of modulations:

frequency (FSK - Frequency Shift Keying); Phase (PSK - Phase Shift Keying);

Quadrature Amplitude Modulation (QAM).

When transmitting signals in one of the selected parameters, the strength is up to the conversion code. The first two types of modulation are transient, so that when transmitting, the signal will change from amplitude to signal. In the last view of the modulation, for the capture of the transgression, there is a more efficient way - quadrature amplitude modulation.

Even if the transmission of the given channels, the call will be heard as soon as the protocols of the transmission of information are accepted.

Transmission protocol - the set of rules, which start the format of the data and the procedure for transmitting through the communication channel, in which, as a rule, modulation methods are used, data transmission from the channel, data transmission, etc. We are always careful to advise the trustworthiness of the donations.

Either modems are capable of transmitting transmission standards, which are established by the International Telecommunication Union (ITU). Name the standard including a number of transmission protocols. One of the most effective standards is the V.34 standard. Winning a test call to the channel, which means that it has the most effective mode of the robot and the modem.

In case of transmission of a great flow of information, if it is presented in a file, for transmission, it is necessary to use special protocols in order to update the transmission of information on blocks, automatically update the transmission, and update the update ... n. Nayposhirenishim and the most effective protocol, which can be used on Russian telephone lines, є Zmodem (file transfer protocol).

For their design, the modem is used for internal and external calls.

An internal modem is a special board that can be wired into the equipment, for example, at the computer's system board, which has a special rose for connecting to the telephone line.

Zovnishny modem (autonomous) - a special attachment (small box), which can be used for a living unit, a rose for connecting to a device (to a computer and a telephone line), a panel with indicators that show how to cut a robot, Can be a regulator for the soundness.

The modem can be used as a contact interface with a communication channel, and contactless (audio), can be designated for other channels in the communication of systems, which can be seen in the broadcast transmission.

In addition to the transmission of given modems, they can display a low brown functions, yak, for example, the number is automatically assigned input link(Caller ID), auto-forwarding function, electronic secretary, reception and transmission of fax messages only.

The number of transmission services in Russia is constantly developing. Have the present moment on the Russian market, the presence of such companies, which are in the order of the decline of the occupied part of the market:

Relcom is the best company that has been able to channel a connection, rented from one of the companies that have a connection protocol, including the Internet protocol;

Rospak is ordered to the state sector enterprises and set up for protocols of series X (XZ, X25,…, X400);

Infotel is a bedroom enterprise of the German company Deutsche Telecom and low Russian companies. Establish the state servants sovereign protocols Serii X, you can access the largest Russian fancywork, bank tributes. The main reason for this is that you need access to the Internet (TCP / IP protocols);

Sprint approved at 1990 r. at the viglyadі of the American-Russian industrial enterprise (the Russian Central Telegraph and the Sprint International company). Servants of the company on the Russian market are vvazhayutsya watchdogs;

Rosnet itself, like the Infotel company, will provide service to the state authorities and establish it behind the state protocols of the X series.

The transmission protocol is the set of rules, which establish the format of the data and the procedure for transmitting them over the communication channel.

Front view:

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Signatures before slides:

Assign that technology to the exchange of information for additional help computer fancy(Merezhevi technologies)

Channels are connected. Transfer of information.

The communication channels are called technical support, so they allow the transmission of data from the driver. Using the communication channels, you can set up a connection for the transmission of information and from distant computers.

Characteristics of the channels in the connection: Throughput - the maximum speed of the transmission of information over the communication channel (Kbit / s)

Sound channels: by coding method: digital and analog; for the method of communication: vision (permanently established) and comutovane (timchasove zednannya); by the method of signal transmission: cable, telephone, radio

Communication channels: Simplex (information is transmitted only in one direction) Duplex (information is transmitted in two directions)

Pereshkodi: - Vlasny pereshkodi; - interchangeably; - Zovnishny pereshkody (subdivided into promises, radio pereskodi, atmospheric and cosmic).

The function of retrieving information when transmitting by channels the call includes three components: Confirmation; the discovery of pardons and information about them; turn at vikhidny camp.

A proxy server is an industrial, transit web server, which is victorious as in the middle between the browser and the web server. Protocol - new dial an operation, one object can work over the same object at once because of the correct order, in which the operation of the operation is wicked; The set of rules governing the format and procedures for exchanging information between two independent processes and annexes.

Internet Work Packet Exchange (IPX) Hyper Text Transfer Protocol (HTTP) Network protocol (network protocol) operating systems: Novell IPX (Inter Packet Exchange), TCP / IP, NetBEUI (Network BIOS User Interface). Transmission Control Protocol / Internet Protocol, TCPMP. The TCP / IP family includes: Telnet protocol; domain addressing system DNS; transmission protocol FTP files; HTTP Hypertext Transfer Protocol.

The main characteristics of the communication channel (Fig. 5.2) are the throughput and reliability of the transmission of data. Channel capacity Estimated by the limiting number of bits of data, which is transmitted by the channel per one hour, and changes in bit / s (s -1). The credibility of the transmission is characterized by the quality of the beat, as for the channels to call without additional charges, to get them from the pardons, call, 10 -4 - 10 -6. The main reason for this is the inflow of a pereskod to the line of the call, and, in some cases, noise in the ADF. Transition to be of an impulsive nature and may tend to the grouping - the adoption of a pack of transcripts, which will simultaneously create a group of suspended bits in a message, which will be transmitted.

Line connection. For transmission of data, a line of communication of different types is required: wire (power), cable, radio relay, fiber-optic and radio channels of ground and satellite communication. Cable lines are stored from twisted pairs of darts or coaxial cables. The main characteristics of the line connection are the smog of the frequencies, the frequency and the efficiency. Smuga frequencies the initial frequency range, de f n i fв - lower and upper frequency range, which is efficiently transmitted over the line. Smuga frequencies lie in the type of line and dovzhini. Drove lines may cause a smog of frequencies of about 10 kHz, cable - 10 2 kHz, coaxial - 10 2 MHz, radio relay - 10 3 MHz and fiber-optic - 10 2 MHz. For transmission of data, short-haul radio links are used from the frequency range from 3 to 30 MHz. Pitom part of the line starts with the vitrates of the line of the line 1 km long. For transmission on small cities, it is important to use low-frequency wire lines, great cities - high-frequency lines: coaxial cables, fiber-optic and radio relay lines. The radio link is stuck in the organization of both the local, and the distant link. The overlap of the line is due to the need for the overlap, but it is established in the line of the new middle, or through the noise in the very line. Naymensh are stable up to the transition to radio transmission, and the harmony to the transition to the voltage of cable lines and visual - fiber-optic lines, not removable to electromagnetism.

Small. 5.4. Sequence of two signals

The bandwidth of the channel. The throughput of the channel is to accumulate from the smog of the frequency of the line of communication and the pressure of the signal and noise. The maximum capacity of the channel, adjusted on the basis of the line of frequencies F signal-to-noise R s / R w, become (bit for a second)

Value (1+ R s / R NS) this is the number of signals in the signal, which can be taken by the receiver. So, like the shutter R s / R w> 3, then a single signal can transfer a number of values, that is, a bit of information.

When transmitting broadly, two signals are received, which receive values ​​of 0 and 1. Timchase diagrams of the sequence of such signals, which are transmitted via a communication link, are shown in Fig. 5.4 are indicated at the top of the value that is carried by the signal. Minimal triviality to the beat, with which signals can be transmitted over the channel with a dark frequency F, door. Yakshko imovіrnіst of the performance of symbols 0 and 1 through the crossroads of the same і dorіvnyu R, then the number of double symbols that can be transmitted by the channel in a second,

Tsei viraz viznacha the throughput of the building of the two-channel canal. The value at the square bows is the starting point of the double symbols, which are transmitted by the channel from the frequency 2 F without a problem. As far as the passage of the day is, the quality of the symbol and the throughput; what is the quality of the performance R= 0.5, then the throughput Z= 0. As the channel is transmitted by n dvіykovy symbol, then yuvіrnіst appear in new l pardon , the average number of pardons and the average quadratic visibility.

The most widespread type of drop - telephone with smogy transmission of 3.1 kHz and a range of frequencies from f H = 0.3 kHz to f H = 3.4 kHz. The switching of the telephone channel will ensure the transmission speed C = 1200 bit / s, and the non-switched one - up to 9600 bit / s.

The efficiency of the transmission of data to the channel is taken to characterize the necessary bandwidth, so that. throughput per 1 Hz smog frequencies to the channel. For the switched telephone channels of the pitom, the throughput of the capacity is taken up at 0.4 bit / (sHz), and for the non-switched channels, it should be called. 3-5 bit / (sHz).

Standardized transmission rates given by channels are: 200, 300, 600, 1200, 2400, 4800, 9600, 12000, 24000, 48000 and 96000 bit / s. Channels with a throughput of up to 300 bit / s are called low-speed, from 600 to 4800 bit / s - medium-high, and with a higher throughput - high-speed.

Transmission methods. For the transmission of data by channels with different characteristics, there are different ways to achieve the maximum control of the authorities of the channels in the promotion of the broadcasting and reliability of the transmission for the same variability of the equipment.

Given a small number of nadayutsya last straight-flow impulses (Fig. 5.4). For transmission without the need for transmission, a smog of frequencies from zero to non-intermittent is required. The real channels may cause the confusion of frequencies, which requires the use of signals to be transmitted. Uzgodzhennya, in a persistent way, with a modulation path - transferring the signal to a given swamp of frequencies і, in a different way, with a coduvannya path - reincarnating tributes from the wigglyad, so that it allows you to see and send graces, to sound into the channel through the crosswalk.

With victorian high-frequency wires cable lines, Smuga frequencies, which can be repaired approximately from zero, signals can be transmitted in a natural view - without modulation (at the first smooth frequencies). Channels, which operate without modulation, are called telegraphs, which will prevent the transmission of data from speed, which, as a rule, is 50-200 bit / s.

Small. 5.5. Channel from modulation

If the channel is heavily surrounded by a smog of frequencies, such as, for example, a radio channel, the transmission of signals is guilty of being in this smoothie and the transferred signal to the smog is carried out for additional modulation behind the circuit shown in Fig. 5.5. In a wide variety of donations to the endowment of the dynasties, the channel will start modem- Modulator and demodulator. Modulator shifting the spectrum of the primary signal to the vicinity of the inconsistent frequency f 0 .Demodulator Visicon over the ringing signal, forming an impulse two-way signal from the modulated signal.

Small. 5.6. Modulation methods

Modulation methods can be used analogsі discrete... Amplitude, frequency and phase modulation are introduced to analog ones (Fig. 5.6). At amplitude(Fig. 5.6, b) the modulation of the amplitude of the non-appropriate frequency is carried out with the primary signal (Fig.5.6, a). At frequency modulation(Fig. 5.6, v) a value of 0 and 1 of a double signal is transmitted by signals at a regular frequency - f 0 that f 1 . At phase modulation(Fig. 5.6, G) signal values ​​0 and 1 correspond to signals of frequency f 0 with a green phase. Discrete modulation methods for the conversion of analog signals, for example, digital, digital. For cycle purposes, the most widespread use is amplitude-pulse, code-pulse and clock-pulse modulation.

Koduvannya tribute, which is transmitted, is mainly used for the promotion of the transfer of tribute. So, the primary codes of symbols can be presented in the transhumanized form - from the vicarious codes of Hemming, which will ensure that the grants are not sent to them. It will remain an hour for the function of advising the validity of the donations to pay on the end of the possession of the donations and to take care of the introduction of information overwhelmingness in the future, so that it will be transmitted.

Transmission equipment. The main purpose of the ADF is to rewire signals, which come from the endpoint, for the transmission of frequencies from the smoothie to the channel, the ringing and reversing of the signals, which come from the channel. Through the telegraph channel, the signals are transmitted without modulation (at the primary smoothing frequencies), the function is used to implement the telegraph signals conversion device, and when the robot is connected to the telephone and high-frequency channel - by the modem. The main elements of the modulator and demodulator are shown in Fig. 5.7. In the given vipadku transmission of the given channel is carried out synchronously with the frequency, similar speed of the robot and the channel, for example, with the frequency of 1200 Hz. Synchronization signals S T molded into a modulator and a clock generator TG... For the skin signal of synchronization S T block of modulation BM a double signal is input T, scho є bit danih. Non-random frequency shaped by a generator LFO... Signal modulation to approach the swamp filter PF, which interconnects the smog of frequencies to the signal up to the lower and upper boundaries of the smog to the channel. Then the signal from a given swarthy frequency is transmitted through the demodulator channel, passes through the swarthy filter, when the specified swarthy frequencies are seen, and it enters the demodulation unit.

The communication channel is a whole system of technical inputs and the middle of the extended signals for transmission of new data (not deprived of these) from the dzherel to the winner (navpaki). The channel of the sound, which seems to be at the higher level of meaning, is, instead of the physical middle, the broadening of signals, for example, the physical line.

When dzherela come to the entrance to the annex (microphone). Transmitting prist_y to re-create signals, as the sound arrives at the input of the channel. On the outgoing channel, a call is received by the receiving signal (telephone capsule) after the received signal, it will be transmitted as soon as it is received, but will not be received at random. The transmission, the channel of the connection and the reception form the system of transmission of information or the system of connection.

For the recognition of the system and communication, the interconnection of the channels of television signaling, television, television control (telecommand), telegraph, telephone, sound communication, facsimile, television communication is small.

The communication channels can be of many different forms, including channels, which can be used to convey the data to others, which can be transmitted as a matter of course, as only the situation is determined.

Add channels to the sound, include:

• Z'єднання між ініціючим and кінцевим vuzls of lantsyug
• Buffer, if you happen to be able to load and reject
• Vid_leniy channel, which will take care of the middle or the physical podil, such as a multi-pair cable, or an electric podil, such as the frequency of the channels, or multiplexing with the time-delayed channels
• Shlyakh for changing the electrical or electromagnet signal
• · A part of the recording middle, such as a dorizhka or a group of dorizhok, which allows you to read or write down a station or add sound.
• In communal systems, chastin, scho z'єdnu dzherelo danih ta priimach danih
• A specific radio frequency, a pair or a frequency range, you call it a letter, a number or a code word and most often seen by an international site
• Space in the Internet Relay Chat (IRC) hedge, in which participants can call one by one

All communal channels supply the power to carry information, as it is carried through the channel by a signal.

When applied to a channel, a specific radio frequency, a pair of frequencies and a range of frequencies, can be used to call the values ​​by a letter, a number by a code word, and most often seen by an international land. Morske UKH radio vikoristovuє deyaki 88 channels in the UKH range for bi-directional frequency-modulated voice communication. Channel 16, for example, means a frequency of 156.800 MHz.

Television channels roztasvani at frequencies, but the initial physical value of a megahertz (MHz). The skin channel is 6 MHz wide. In addition to physical channels, television channels are also available. Wi-Fi ( mouthless fingering) is a communication channel, which can be stored from non-licensed channels 1-13 in the range from 2412 MHz to 2484 MHz at a rate of 5 MHz.