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Wireless interfaces for such a device. Wireless interfaces

Bluetooth (blue tooth) is the actual standard for miniature inexpensive means of transmitting information using radio communications between mobile (and desktop) computers, mobile phones and any other portable devices For short distances. The development of the specification is engaged in a group of leading firms in telecommunications, computers and network areas - 3COM, Agere Systems, Ericsson, IBM, Intel, Microsoft, Motorola, Nokia, Toshiba. This group forms a Bluetooth Special Interest Group and brought out this technology To the market. The Bluetooth Specification is freely available on the network (www.bluetooth.com), however, it is quite voluminous (about 15 MB of RDF files). The openness of the specification should contribute to its rapid distribution, which is already observed in practice. Here we allow yourself to reduce the name of technology to "W" (this is not an official reduction). The name itself is a nickname of the Danish king, united by Denmark and Norway, is a hint of a universal combining role of technology.
Each WP device has a radio transmitter and receiver operating in the frequency range of 2.4 GHz. This range in most countries is assigned to industrial, scientific and medical equipment and does not require licensing, which ensures the widespread applicability of devices. For W, radio channels are used with discrete (binary) frequency modulation, carrier channels F \u003d 2402 + K (MHz), where K \u003d 0, ..., 78. For several countries (for example, France, where military operates in this range) is possible Abbreviated version with f \u003d 2454 + k (k \u003d 0, ..., 22). The coding of a simple - logical unit corresponds to the positive frequency deviation, zero-negative. Transmitters can be three power classes, with a maximum capacity of 1, 2.5 and 100 MW, and the possibility of lowering the power with the target-saving energy should be.
Transmission is conducted with a cross-bearing frequency with one radio channel to another, which helps in the fight against interference and signal fading. Physical channel Communications seems to be a specific pseudo-random sequence of radio channels used (79 or 23 possible frequencies). A group of devices separating one channel (that is, "knowledgeable" one and the same sequence of the jumps), forms the so-called piconeet (Piconet), which can be from 2 to 8 devices. Each picosette has one leading device and up to 7 active slaves. In addition, in the coverage area of \u200b\u200bthe leading device in its same picoseti may be "parked" slave devices: they also "know" the consistency of the jumps and synchronize (by jumps) with the leading device, but can not exchange the data until the leading device is not Allow their activity. Each active led fiberglass has its own temporary number (1-7); When the slave device is deactivated (parked), it gives its own number to use by others. When subsequent activation, it can already get a different number (because it is also temporary). Picoseti can overlap coverage zones by forming a "scattered" network (Scatternet). At the same time, in each picoseti, the drive device is only one, but the slave devices can enter several picosets using the separation of time (part of the time it works in one, part is in another picoseti. Moreover, the leading device of one picoseti can be a slave device of another picotter. These picosetics are not synchronized, each of them uses its channel (consistency of the rear.).
The channel is divided into time slots with a duration of 625 μs, the slots are sequentially numbered with cyclicity 2 ". Each time slot corresponds to a single frequency carrier in the flow of the jumps (1600 of the robs per second). The frequency sequence is determined by the address of the leading peak sequence. Transmission is carried out by packages, each A package can occupy from 1 to 5 time slots. If the package is long, then it is all transmitted on one carrier frequency, but 625 ISS slot counts continues, and after a long packet, the next frequency will correspond to the next slot number (that is, several jumps will be skipped. ). The drive and slave devices lead the transfer alternately: in even slots, the transmission leads the leading device, and in the odd - the driven device addressed to them (if it is what "say").
The physical connections of two types can be installed between the leading and driven devices: synchronous and asynchronous.
Synchronous connections(They are isochronny) with establishing a connection, SCO Link (Synchronous Connection-Oriented) are used to transmit isochronous traffic (for example, digitized sound). These links of the "point-to-point" type pre-set the master device with selected driven devices, and for each connection the period (in slots) is determined through which slots are reserved for it. Communications are obtained symmetric bilateral. Repeated packet transmission in case of reception errors are not used. The master can be installed up to three SCO connections with one or different slave devices. The slave can have up to three connections with one master device or have one SCO connection with two different leading devices. Network classification of SCO communication relate to switching chains.
. Asynchronous connectionswithout establishing a connection, ACLLINK (asynchronous Connection-Less) implements switching packagesaccording to the "point-multiple point" scheme between the leading device and all the driven devices of the picoseti. The master can be associated with any of the driven peak devices in slots not occupied by SCO, sending a package to him and demands an answer. The slave device has the right to transfer, only receiving the driver request addressed to it (unmistakably decoding its address). For most types of packages, retransmission is provided if the reception error is detected. The drive device can send both non-aligned broadcast packets for all driven devices of their picoseti. With each of their driven devices, the master can be installed only one ACL connection.
Information is transmitted by packets in which the data field may have a length of 0-2745 bits. For associating ACLthere are several types of packets with a CRC code protection (if an error is detected, re-transmission is provided) and 1 defenseless (without repeat gear). For SCO connectionsthe data is not protected by the CRC code, and therefore repeated transmissions on the reception error are not provided.
Protection of data from distortion and monitoring of reliability is made in several ways. The data of some types of packages are protected by the CRC code, and the information receiver must confirm the reception of the correct package or report acceptance error. To reduce the number of repetitions, excess encoding FEC (Forward Error Correction Code) is applied. In the EEC 1/3 scheme, each climb batch is transmitted three times, which allows you to choose the most believable majority option. The FEC 2/3 scheme is somewhat more complicated, it uses the Hamming code here, which allows you to correct all one-time and detect all double errors in each 10-bit block.
Everyone voice channelprovides a speed of 64 kbps in both directions. The Channel can use coding in PCM format (pulse-code modulation) or CVSD (Continuous Variable Slope Delta Modulation - version of the adaptive delta of the pulse-code modulation). RSM encoding allows compression by G.711; It provides only a purely "telephone" quality of the LA (meaning digital telephony, 8-bit samples with a frequency of 8 kbps). CVSD encoder provides more high quality - It packs the input RCM signal with a frequency of samples 64 kbps, however, and at the same time the spectral density of the signal in the frequency band of 4-32 kHz should be insignificant. To transfer high-quality audio alarm voice (speech) WW channels of nonsense, however, a compressed signal (for example, a MPZ stream) can be performed using an asynchronous data channel.
Asynchronous canal It can provide a maximum speed of 723.2 kbps in an ASEM of a metric configuration (leaving for the reverse channel of the strip 57.6 kbps) or 433.9 kbps in each direction in a symmetrical configuration.
To ensure security in W authentication and data encryption At the level of communication (Link Layer), which, of course, can be complemented by the means of the upper protocol levels.
An important part of W is sDP service detection protocol(Service DISSOVERY Protocol), allowing the device to find a "interesting interlocutor". In the future, by setting the connection with it, the device will be able to VTCMCZ required services (for example, to display documents for printing, connect to the network, etc.).
RFCOMM protocol Provides the serial port emulation (9-wire RS-232) via L2CAP. With its help, traditional cable connections of devices (including zero-modem) can be easily replaced by radio communication, without any modifications at the upper levels. The protocol allows you to establish and multiple connections (one device with several), and the Diarosyaz will replace bulky and expensive multiplexers and cables. Through the protocol, the RFComm can work the Oven Protocol used in infrared wireless connections (in the IRDA hierarchy). The RWP protocol is also working on RFComm, over which the TCP / IP stack protocols are standing, it opens the road to all applications for the Internet. Through RFComm, the AT-commands, controlling telephone connections and fax transmission services (the same commands are used in modems for switched lines).
Special bit-oriented telephone protocol TCS BIN (TELEPHONY CONTROL PROTOCOL - BINARY), defining a call signaling to communicate the WTC (speech communication and data exchange), also works through L2CAP. The protocol has both TCS device groups.
HCI Host Coitromer Interface Host Controller Interface is a uniform access method to the low levels of the low levels of W. It provides a set of commands to manage radio communications, obtain information about the status and data transmission itself. Through this interface, the L2CAP protocol is interacted with WP equipment. Physically, the WP can connect to various interfaces: extension bus (for example, PC Card), USB bus, CQM port. For each of these connections, there is an appropriate HCI transport link protocol - a layer providing HCI independence from the connection method.

Wireless interfaces are used to transfer data to distances from several tens of centimeters to several kilometers. They are most convenient for users, but at short distances their cost above wired. Nevertheless, they are in demand in all their own options, and wireless technologies are now developing extremely intensively.

ECM wireless interfaces can be divided into two groups:

1. Interfaces intended for connecting to computer peripheral devices (keyboards, mice, printer, scanner, external memory, etc.) and laptop computers (PDA, laptop, etc.).

2. Interfaces for connecting a computer to computer networks (local, regional, corporate, Internet).

The first group of interfaces includes IRDA infrared interfaces, radio interfaces: Bluetooth, WUSB, WSATA, etc. The second group includes interfaces WiFi, WiMAX, etc.

End of work -

This topic belongs to the section:

Main computers of computer, their purpose and functional characteristics

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Abstract Leccіj
C disciplini "Architecture Comp" YTERIV "for Studentіv 2 exchange rate for special transition 6.0915.01" Comp "Uternі system of TA Merezhі" Delphid 0915 "Comp.Uneerna Інжерер

Microprocessor
Microprocessor (MP) is a PC central device, designed to manage the operation of all blocks of the machine and for performing arithmetic and logical information on information. M.

System tire
The system bus is the main computer interface system, which ensures the conjugation and connection of all its devices among themselves. The system bus includes: □ Code Type Data Tire (CH

Main memory
The main memory (OP) is intended for storing and promptly exchange information with other blocks of the machine. OP contains two types of storage devices: a constant storage device (ROM) and about

External memory
External memory relates to external PC devices and is used for long-term storage of any information that may ever need to solve problems. In particular, in the external memory

External devices
External devices (Wu) PC - the most important component Any computing complex, it suffices to say that at the cost of Wu make up to 80-85% of the cost of the entire PC. Wu PC providing

Additional integrated chips
To the System Bus and to the MP PC, along with type external devices, some additional integral chips, expanding and improving the functionality of the MICRO can be connected.

PC design elements
Constructively PCs are made in the form of a central system unit to which external devices are connected through connectors: additional memory blocks, keyboard, display, etc.

Functional characteristics of EUM.
The main functional characteristics of the computer are: 1. Performance, speed, clock frequency. 2. Bigness of the microprocessor and code tires of the interface.

Performance, speed, clock frequency
The performance of modern computers is usually measured in millions of operations per second. Measurement units are: □ MIPS (MIPS - Millions Instruction Per Second) - for operations

Bigness of the microprocessor and code tires interface
The size is the maximum number of binary digits, over which the machine operation can be performed simultaneously, including the transmission transmission operation; the greater the discharge

Type and capacity of RAM
The capacity (volume) of RAM is usually measured in megabytes. We remind you that 1 MB \u003d 1024 KB \u003d 10242 bytes. Many modern applied programs with operational memory

Availability, types and capacity of cache
Cash memory is a buffer, unavailable high-speed memory, automatically used by the computer to speed up operations with information stored in more slowly acting

Questions for self-test
1. Draw a block diagram of a personal computer. 2. Give the characteristic of the main blocks of the computer. 3. Give brief description devices included in the microprocessor.

Microprocessors
The most important components of any computer that determine its main characteristics are microprocessors, motherboards and interfaces. Microprocessor (MP),

Microprocessors type CISC.
Most modern IBM PC type PCs are used by CISC type MP, manufactured by many firms: Intel, AMD, Cyrix, IBMI, etc. "Model Model" here performs Intel, but her "

Pentium microprocessors
Microprocessors 80586 (P5) are more famous for their Pentium trademark, which is patented by Intel (MP 80586 other firms have other designations: K5 from AMD, ML from Cyrix, etc.). E.

Microprocessors Pentium Pro.
In September 1995, the MP of the sixth generation 80686 (P6) was issued, the Pentium Pro trademark. The microprocessor consists of two crystals: actually MP and cache memory. But it is not fully compatible with

Pentium MMX and Pentium II microprocessors
In 1997, upgraded to work in multimedia technology Pentium and Pentium Pro microprocessors that have received brands, respectively, Pentium MMX (MMX - Multimedia Extent

Microprocessors Pentium III
Pentium III (CopperMine) processors that appeared in 1999 are further development Pentium II. Their main difference is based on a new block of 128-bit registers Expansion

Microprocessors Pentium 4.
Modification of MP Pentium - Pentium 4 - designed for high-performance computers, primarily servers, workstations of the High-End class and multimedia game PCs. Consider the basic

NT technology
Hyper Treading Technology (Tread - Stream) implements multi-threaded program execution: on one physical processor you can simultaneously execute two tasks or two streams of commands of one program

RAID technology
Most of the new microprocessors support Intel RAID technology (Redundant Array Intensive Disk - an array of inexpensive redundancy discs). The advantage of this technology is simplicity

NEW MARKING MP Firms Intel
Since 2004, Intel introduces new marking of its microprocessors. Entered by a single three-digit processor number will take into account several characteristics at once: basic architectures

Microprocessors Over Drive.
The interest of MP Over Drive is essentially peculiar coprocessors providing for MP 80486 modes of operation and efficient speed characteristic of MP Pentium, and for

RISC type microprocessors
RISC type microprocessors contain only a set of simple, most often found in command programs. If necessary, performing more complex teams in the microprocessor is automatically performed.

Microprocessors type VLIW.
This is a relatively new and very promising type of MP. Microprocessors of type VLIWV 2004 years produced firms: □ TRANSMETA - this is a Crusoe M microprocessor

Physical and functional structure of the microprocessor
The physical structure of the microprocessor is quite complex. The processor core contains the main managing and executing modules - blocks of operations over integer data. To local governance

Control device
The control device (UU) is functionally the most complex PC device - it produces control signals entering the instructions (KSH) code tires in all blocks of the machine. Simplified

Arithmetic logical device
The arithmetic and logical device (Allu) is intended for performing arithmetic and logical information conversion operations. Found in the simplest version of Alu (Fig. 8.2) SOS

Microprocessor memory
Microprocessor memory (MPP) of the basic MP 8088 includes 14 double-byte storage registers. MP 80286 and above there are additional registers, for example, MP type VLIW E

Universal registers
Registers AH, WX, CX and DX are universal (they are often called general-purpose registers - Ron); Each of them can be used to temporarily storing any data, while allowed

Segment registers
CS, DS, SS segment addressing registers are used to store initial memory field addresses (segments) allocated in storage programs1: □ Program commands

Shifts registers
The offset registers (intra-segment addressing) IP, SP, BP, SI, DI are designed to store relative memory cells in the segments (displacements relative to the start of the segments): & n

Register Flags
Flag register F contains conventional single-digit-mask signs, or flags that manage the passage of the program in the PC; Flags work independently of each other, and only for convenience they are placed in one

Questions for self-test
1. Give a brief characteristic of the microprocessor, its structure, destination, the main parameters. 2. Name and explain the main functions performed by the microprocessor. 3. Name

System fees
System (System Board, SB), or back, maternal (Mother Board, MB) Plata is the most important part of the computer containing its main electronic components

Symbols of system plats
Currently, dozens of firms produce a large number system Plasteps, differing and constructively, and by the type of microprocessors supported by them, and on the clock frequency of their work, and the largest

Chipsets of system board
Microprocessors installed on the motherboard, in a specific range of models can be changed, and the main non-permanent functional component of the joint venture is a set of systemics

Questions for self-test
1. Explain the role of the motherboard in the PC. 2. Name the main devices located on the PC system board. 3. Name the main formats of system boards. 4. Give brief

Interface systems EUM.
Interface (Interface) is a set of interface and communication tools that ensure effective interaction of systems or their parts. (In computer literature sometimes VM

Tires extensions
1. PC / XT bus - 8-bit data bus and a 20-bit address bus, designed for a clock frequency of 4.77 MHz; It has 4 lines for hardware interrupts and 4 channels for direct memory access (channel

Local tires
Modern computing systems are characterized by: □ rapid growth of microprocessors and some external devices □ the appearance of programs requested

Peripheral tires
Peripheral tires provide the connection of the central devices of the machine with external devices (disk drives, keyboard, mouse, scanner, etc.). They are external interfaces

Universal sequential tires
In 2003-2004, revolutionary changes occurred in computer interface systems: first there was a coup in the direction of consecutive interfaces, and in 2004 they began to actively develop and were actively developed

Serial USB bus
The first and most common sequential bus is a USB (Universal Serial Bus) - a universal sequential tire. She appeared in 1995 and was called upon to replace such obsolete

Standard IEEE 1394.
IEEE 1394 (Institute of Electrical and Electronic Engineers 1394 - Standard Institute of Electrical Engineering and Electronics Engineers 1394) - a new and promising serial interface, intended

SATA serial interface
At the end of 2000, the Working Group (Intel, IBM, Maxtor, Quantum, Seagate, etc.) announced a new Extremely efficient Serial ATA serial interface (SATA), providing

PCI Express Serial Interfaces Family
Perhaps the most promising and is of substantial interest of the PCI EXPRESS serial interfaces, information about the basic protocol of which appeared in July 2002. PCI EXPRES.

Irda interfaces
One of the first wireless interfaces that have been used in computers was the IRDA standard, the connection in which is carried out along the infrared radiation channel. Infrared range was used

Bluetooth interface
Bluetooth - technology transfer technology by radio channels in the frequency range of about 2.5 GHz for short distances even in the absence of direct visibility between devices. Originally bluetoot

Interface WUSB.
Intel as the basic replacement Bluetooth suggested a wireless version of the USB interface - WUSB interface (Wireless USB), which, according to its forecasts, was to be out of way "Blue W

WiFi Interface Family
WiFi interfaces refer to a group of interfaces that provide wireless computers to networks. Basic standard IEEE 802.11 or WiFi (Wireless Fidelity - "Wireless Devotion") was ra

WiMAX interfaces
WiMAX wireless technology is the commercial name of the IEEE 802.16A standard declared in January 2003. This is the third version of the IEEE 802.16 standard, first proposed in December 2001

Other interfaces
□ PCMCIA (Personal Computer Memory Card International Association - Memory Card Manufacturers Association for Personal Computers) - External Tire Computers of Laptop Class. Other Naz

Questions for self-test
1. What is the interface? 2. What functions performs the interface? 3. Give a brief description of the ISA bus. 4. Give a brief description of the PCI interface family.

Storage devices PC
Personal computers have four levels of memory: □ microprocessor memory (MPP); □ register cache; □ basic memory (OP);

Static and dynamic RAM
RAM can be compiled from dynamic memory chips (DRAM) or static (Static Random Access Memory - SRAM) type. Static memory

Register Cash Memory
Register cache - high-speed memory of a relatively large container, which is a buffer between OP and MP and allowing to increase the speed of operations. Cache-Memory Registers

Physical structure of the main memory
The simplified structural scheme of the main memory module in the matrix organization is presented in Fig. 11.1. When a matrix organization, the cell address entering the address register, for example

DIP, SIP and SIPP
DIP (DUAL IN-LINE PACKAGE - Housing with a two-row arrangement of outputs) - a single memory chip, is now used only in the composition of the enlarged modules (as part of the SIM modules

FPM Dram.
FPM DRAM (fast page mode DRAM) - dynamic memory with fast page access, is actively used with microprocessors 80386 and 80486. Page access memory is different

RAM EDO.
RAM EDO (EDO - Extended Data Out, extended holding time (availability) of data at the output), in fact, are conventional FPM chips to which the set is added

Bedo Dram.
Bedo Dram (Burst Extended Data Output, EDO with block access). Modern processors Thanks to the internal and external caching of commands and data exchange with the main memory

DDR SDRAM
DDR SDRAM (DTA RATE SDRAM - SDRAM II). An SDRAM memory version that transmits information on both fronts of the clock signal. This allows you to double the bandwidth.

Permanent storage devices
A constant storage device (ROM, or ROM-READ Only Memory, read-only memory) is also built based on modules installed on the motherboard (cassettes) and

The logical structure of the main memory
Structurally, the main memory consists of millions of separate single-byte memory cells. The total capacity of the main memory of modern PCs usually lies in the range from 16 to 512 MB. Capacity

External storage devices
Foreign memory devices, or, otherwise, external storage devices (VIS) are very diverse. They can be classified for a number of signs: by type of carrier,

Files, their types and organization
The file is called a named set of data on the external medium of information. In PC, the concept of a file is used mainly to data stored on disks (less often - on a cassette magnetic tape

File Management
Access is called the file access to read or write information into it. The file system supports two types of file access: □ Serial Access Method;

File attributes
The attribute is a classifying feature file that determines how to use it, the access rights to it, etc., DOS allows you to specify the following elements in the attribute:

Logic file system organization
Streamlining files stored in disk memory is called a logical organization file System. The basis of the logical organization are catalogs. The catalog is a special file, in

File specification
In order to operating system Could contact the file, you must specify: □ disk; □ Catalog; □ Full file name. This information is infected

Placing information on disks
Disk tracks are divided into sectors. In one track sector, 512 data bytes is usually located. Data exchange between NMD and OP is carried out in series clusters.

Addressing information on disk
Are used the following systems Addressing information on MD: □ in BIOS - three-dimensional: cylinder number (track), magnetic head (disk side), sectors; □ in DOS - after

Storage drives on hard magnetic disks
Storage devices on hard magnetic disks (NGMD, hard drives, Hard Disk. Drive - HDD) are devices intended for long-term storage of information. As on

Portable disk drives
Recently, portable drives (they are also called external, mobile, removable, and their portable options - pocket - Pocket HDD) were widespread. Portable meals

JAZ 1GB, JAZ 2GB
JAZ 1GB models, JAZ 2GB developed by Iomega (JAZ 1GB support hard disks with a capacity of 1 GB, and JAZ 2 GB drives are disks with a capacity of 1 and 2 GB). Iomega Jaz 2GB disk

ZIV1, ZIV2.
ZIV-very elegant miniature 2.5-inch form factor disk drive with a special controller connected to uSB interfaces 1.1 (ziv1) or USB 2.0 (ZIV2). Typical size

Disk arrays RAID
In database servers and supercomputers, RAID disk arrays are often used (Redundant Array of Inexpensive Disks - an array of low-cost redundancy discs) in which several

Drives on flexible magnetic disks
Drive drives on flexible magnetic disks (NGMD, floppy drives, Floppy Disk Drive, FDD) - devices designed to record and read information from flexible magnetic disks (gmd, d

Storage devices on floppy disks
The storage devices on flip discs are the usual magnetic record of information, but with a significantly greater density of the tracks on the disk surface. Such density is achieved

Zip drives
The most common after floppy drives (FDD) flexible drive drives are ZIP drives developed by Iomega in 1995. ZIP devices are based on tradition

Formatting discs and rules for handling them
Each new disk at the beginning of working with it should be formatted. Disc formatting is the creation of the information recording structure on its surface: marking tracks, sectors, record markers and other

Optical drives
Appeared in 1982, thanks to Philips and Sony firms, the optical CD made a cardinal coup in the field of personal computers and the entertainment industry. Compact-D.

Non-recipient CD-ROM laser and optical discs
Mass distribution received CD-ROM. The CD is a plastic polycarbonate circle with a diameter of 4.72 inches (there are 3.5 compact disks with a diameter of 3.5; 5.25; 12 and 14 inches) and that

Optical discs with a single recording
CD-R drives allow you to record information on disks with form factor 4.72 and 3.5 inches. For recording, special disk blanks are used, sometimes called Dwarcs (Target). On the

Optical disks with multiple recording
CD-RW drives allow multiple information on the discs with a reflective surface, which is applied by a layer of type Ag-in-SB-TE (containing silver, indium, antimony, tellurium) with variable f

DVD digital discs
The real coup in the technique of external storage devices is ready to make new, first digital video foundations that have known in 1996, having the dimensions of ordinary CD-ROMs, but significantly greater EMC

Magneto-optical drives
The principle of operation of the magneto-optical drive (Magneto Optical) is based on the use of two technologies - laser and magnetic. Recording information is carried out on magnetic carrier

Magnetic tape drives
Magnetic ribbon drives were the first to have computing machines. In universal computers, storage devices on a rebel magnetic tape (NML) were widely used, and in PERS

Flash memory devices
Flash disks (Flash disks) is a very popular and very promising class of non-volatile storage devices. Flash discs ( solid-state discs) are the modification of HDD and are must

Questions for self-test
1. Give the classification of PC storage devices and give a brief description of individual classes. 2. What is and where static rAM, dynamic operatives

VideoTerminal devices
VideoTerminal devices are designed to prompt text and graphic information In order to visually perceive its user. The video terminal consists of out

Video monitors based on CRT
The monitor includes: □ electron beam tube; □ scan unit; □ VideoSiller; □ power supply, etc. Electron beam

Monochrome monitors
Monochrome monitors are substantially cheaper than color, have a clearer image and greater resolution, allow you to display tens of shades of "gray", less harmful to health

Colored monitors
In the color CRT monitor, three electron guns are used, in contrast to one gun used in monochrome monitors. Each gun is responsible for one of the three main colors: Red (Red

Types of scan images on the monitor
The scan unit can be submitted to the deflecting system of the voltage monitor of different shapes, on which the type of scanning of the image depends. There are three types of sweep: □ raster;

Digital and Analog Monitors
Depending on the type of signal control signal, monitors are analog and digital. In analog monitors, manual control is based on rotary potentiometers, in digital -

Screen size monitor
Monitors are available with screens of different sizes. The size of the monitor screen is usually set to its diagonal in inches: for IBM PC-compatible PCs, sizes of screens 12, 14, 15,

Vertical (personnel) sweep
An important characteristic of the monitor is the frequency of its frame sweep. Changing images (frames) On the screen with a frequency of 25 Hz is perceived by the eye as a continuous movement, but the eye is due to

Resolution monitor
Video monitors can usually work in two modes: text and graphic. In text mode, the image on the monitor screen consists of the displayed symbols of the extended ASCII, F

Frequency bandwidth
The frequency bandwidth is an important independent value, since it depends on the image clarity on the screen (very often only this value is indicated on the box from the monitor).

Ergonomics of electron-ray monitors
The ergonomics of the monitor is determined by the successful selection of such characteristics as the quality of the picture on the screen, dimensions, weight, design of the monitor, and, to a greater extent, harmlessly

TSO-99 standard
Requirements that TSO-99 presents to conventional electron-beam (CRT) monitors are divided into 6 main categories. In the first two combined properties characterizing visual ergonomics

Protective filters for monitors and their choice
So, even if the video monitor fully meets the requirements of the international MPR-2 standard (Low Radiation displays), additional protection is desirable from its radiation. Proposals for this account

Monitors on liquid crystal indicators
Monitors on liquid crystal indicators (LCD, LCD - Liquid Crystal Display) are digital flat monitors. These monitors use a special transparent liquid, which when

Plasma monitors
In plasma monitors (PDP - Plasma Display Panels), the image is formed by the accompanied radiation of light by gas discharges in the panel pixels. Structurally, the panel consists of three glass

Electroluminescent monitors
Electroluminescent monitors (FED - Field Emission Display) are used as a panel with two thin glass plates with transparent wires applied to them. One of these plates is covered with

Light-emitting monitors
In light-emitting monitors (LEP - Light Emitting Polymer) is used as a panel of a semiconductor polymer plate, the elements of which under action electric current Start shining

Stereonitors
A second generation of monitors creating a three-dimensional image is developed. To create a three-dimensional (3D), or rather stereoscopic image, it is necessary to show the left and right ch

Video controllers
The video controller (video adapter) is an intrasystem device converting data to a signal displayed by a monitor and directly controlling monitor and output.

Questions for self-test
1. Give a multi-speech classification of monitors. 2. List and explain the main parameters taken into account when choosing an ETT monitor. 3. Explain the main factors affecting

Keyboard
The keyboard is the most important device for the user with which data, commands and control influences in the PC are entered. Latin and National letters are applied on the keys

Graphic manipulator mouse
It should be briefly stopped at another type of device input devices in the PC. We are talking about graphic manipulators, which uses touch screens, Table

Printers
Printing devices (printers) are data output devices from the computer, converting ASCII codes and bit sequences to the corresponding symbols and fixing

Matrix printers
In matrix printers, the image is generated from the points by the shock mode, so they are more correctly called shock-matrix printers, especially since other types of sign-sensing printer

Inkjet printers
These are the most common printers currently. Inkjet printers In the printhead, instead of needles have thin tubes - nozzles, through which the smallest droplets are thrown on paper

Laser printers
Laser printers provide the highest quality printing with the highest resolution and speed. They use the electrographic method of forming images used

Thermal printer
Thermal printer belongs to the group of matrix printers. They use the thermomomatrix and a special thermal paper or a thermal circuit. The principle of the thermal printer's action is very simple. Print

Hardering printers
Harder technology was developed by Tektronix, which is part of the Xerox company. Dyes used in a hardening printer are solid cubes

Service devices
High-speed printers, as already noted, have their own buffer memory used both when exchanging data from PC and storage of loaded fonts. Memory from matrix sky printers

Network printers
Network printer - A printer having an IP address and, thus, a peculiar website. You can contact such a printer through an IP address using a conventional browser, extract full info

Scanners
The scanner is an input device to a computer information directly from a paper document. It can be texts, schemes, drawings, graphics, photos and other information. Scanner, P.

Types of scanners
Manual scanners are structurally the simplest - they consist of a line of light diodes and a light source placed in a single case. Moving on the image of such a scanner

Vector
In a raster format, the image is remembered in the file in the form of a mosaic set of multiple points corresponding to the pixels of displaying this image on the display screen. File, create

Digitizers
Digitizer (Digitizer), or a graphic tablet, is a device, the main purpose of which is digitizing images. It consists of two parts: base

The main characteristics of digitizers
Digitizers are: □ electrostatic; □ electromagnetic. In electrostatic digitizers, a local change in electrostatic change is recorded

Plotters
Plotters (Plotter, Clap-Builder) - Devices for displaying graphic information (drawings, schemes, drawings, diagrams, etc.) from the computer on a paper or other type of carrier.

Types of plotters
Feather plotters (Pen Plotter) are an electromechanical device of vector-type, in which the image is created by drawing lines using a writing element, generalizedly called

Questions for self-test
1. Name and briefly describe the main types of keyboards. 2. Name and briefly describe the main varieties of graphic manipulators. 3. Name the main

Lecture13. Peripheral wireless interfaces

1. IRDA infrared interface

2. Radio interface Bluetooth

1. IRDA infrared interface

Wireless interfaces allow you to free the devices from binding their interface cables, which is especially attractive for small peripherals, in size and weight commensurate with cables. In wireless interfaces, electromagnetic waves of infrared (IRDA) and Radio Frequency (Blue Tooth) ranges are used. In addition to these interfaces of peripheral devices, there are wireless ways to connect to local networks.

The use of emitters and receivers of infrared (IR) range allows you to carry out a wireless connection between a pair of devices remote to a distance of several meters. Infrared communication - IR (Infrared) Connection - safe for health does not create interference in the radio frequency range and ensures the privacy of transmission. The IR rays do not pass through the walls, so the reception area is limited to a small, easily controlled space. Infrared technology is attractive to communicate portable computers with stationary computers or PU. Infrared interface have some models of printers, they equip many modern small-sized devices: pocket computers (PDA), mobile phones, digital cameras, etc.

Infrared systems distinguish:

Low (up to 115.2 kbps)

Middle (1,152 Mbps)

High (4 Mbps) speed.

Low-speed systems serve to exchange short messages.

High-speed - to exchange files between computers, connecting to a computer network, output to a printer, projection machine, etc. Higher exchange rates are expected to transmit "live video".

In 1993, the Association of Developers of Infrared Data Transmission Systems Irda. (Infrared Data Association), Designed to ensure the compatibility of equipment from various manufacturers. Currently there is a standard IRDA 1.1, Along with which their own systems of Hewlett Packard - HP-Sir. (Hewlett Packard Slow Infra Red) and Sharp. - Askir. (Amplitude Shifted Keyed IR). These interfaces provide the following transmission speeds:

· IRDA SIR (Serial Infra Red), HP-SIR - 9.6-115.2 kbps;

· In IRDA HDLC, known as IRDA MIR (MIDDLE INFRA RED) - 0.576 and 1,152 Mbps;

· IRDA FIR (Fast Infra .red) - 4 Mbps;

· Askir - 9.6-57.6 Kbps.

Emitter for IR communication is an LED having a peak of the spectral characteristic of the power of 880 nm. The LED gives a cone of effective radiation with an angle of about 30 °. Pin-diodes are used as a receiver, effectively taking IR rays in 15 ° cone. The IRDA specification defines the requirements for the power of the transmitter and the sensitivity of the receiver, and the receiver is given both the minimum and maximum power of IR rays. The pulses of too low power receiver will not "see", and too much power "blinds" the receiver - the received pulses are separated into an indistinguishable signal.

In addition to the useful signal to the receiver, interference is affected: illumination of solar lighting or incandescent lamps, which gives a constant component of optical power, and interference from luminescent lampsgiving a variable (but low-frequency) component. These interference have to filter. The IRDA specification provides bit error levels (BER-BIT ERROR RATIO) no more than 10 9 with a range of up to 1 m and daylight (illumination - up to 10 keys).

Specification Irda. Determines the multi-level protocol system, which will look at the bottom up.

Listed below possible options Irda. At the physical level.

· Irda Sir. - For speeds of 2.4-115.2 kbps, a standard asynchronous transmission mode is used (as in som port): start-bit (zero), 8 data bits and stop bits (single). The zero bit value is encoded by a pulse with a duration of 3/16 bite intervals (1.63 μs at a speed of 115.2 kbps), a single - lack of pulses (mode Irda Sir-A). Thus, in a pause between the parcels, the transmitter does not shine, and each package begins with a start-bit pulse. In Specification 1.1, another mode is also provided - IRDA SIR-B, With a fixed pulse duration of 1.63 μs for all these speeds.

· Ask Ir. - For speeds 9.6-57.6 kbps, asynchronous mode is also used, but the encoding is different: zero bit is encoded by the passage of pulses with a frequency of 500 kHz, a single - lack of pulses.

· Irda. HDLC. - Speed \u200b\u200b0.576 and 1.152 Mbit / s uses synchronous transmission mode and encoding, similar to SIR, but with a 1/4 bit-interval pulse duration. The frame format corresponds to the HDLC protocol, the beginning and end of the frame are marked with flags 01111110, inside the frame This bit sequence is excluded using bits insertion (Bit Stuffing). To control the reliability, the frame contains a 16-bit CRC.-the code.

· Irda Fir. (IRDA4PPM) - Synchronous mode is also used for 4 Mbps speed, but the coding is somewhat more complicated. Here, each pair of adjacent bits is encoded by a positional and impulse code: 00 - 1000, 01 - 0100, 10 - 0010, 11 - 0001 (in fours of symbols, the unit means the parcel of the pulse in the corresponding quarter of the two-bed interval). This encoding method allows twice to reduce the inclusion frequency of the LED compared to the previous one. The constancy of the average frequency of the received impulses, facilitates adaptation to the level of external illumination. A 32-bit CRC code is applied to enhance reliability.

Over the physical level is located protocol access IRLAP. (IRDA. Infrared Link Access Protocol) - Modification of the HDLC protocol, reflecting the needs of IR communications. It converts data to frames and prevents device conflicts; If there are more than two devices, "adding" each other, one of them is administered primary, and the rest are secondary. Communication is always half duplex. IRLAP. Describes the procedure for establishing, numbering and closing the compounds. The connection is set at a speed of 9600 bps, after which the exchange rate of maxima from those available by both (9.6, 19.2, 38.4, 57.6 or 115.2, 38.4, 57.6 or 115.2, Kbps) is accomplished and logical channels are installed (each channel Managed by one master device).

Over IRLAP. located connection management protocol IRLmp IRDA Infrared Link Management Protocol).With it, the device reports the rest of his presence in the coverage area (device configuration Irda. It may vary dynamically: it is enough to reduce the new device to change it or take it away). Protocol IRLmp Allows you to detect the services provided by the device, check the data streams and act as a multiplexer for configurations with a multitude of available devices. Applications using IRLMP can find out if the device required is present in the coverage area. However, this protocol does not provide guaranteed data delivery.

Transport level Provided by the protocol Tiny TP. (Irda Transport Protocols) - Virtual channels between devices are served here, errors are processed (lost packets, data errors, etc.), data packaging in packets and assembly of source data from packets are made (the protocol resembles TCP.). Protocol can work at the transport level IRTP..

Protocol Ircomm. Allows you to emulate the usual wired connection through an IR connection:

· 3-wire RS-232C (TXD, RXD and GND);

· 9-wire RS-232C (the entire set of SOM port signals);

· Centronics (parallel interface emulation).

Protocol IRLAN. provides access to local networks; It allows you to transmit network frames Ethernet and Token Ring. For IR connection to the local network requires a device provider with an interface Irda.connected by the usual (wired) method to the local network, and the corresponding software support in the client device (which must be logged in).

Object exchange protocol Irbex (Object Exchange Protocol) - A simple protocol that defines the PUT and GET commands to exchange "useful" binary data between devices. This protocol is located above the Protocol. Tiny Tr.. Protocol Irbex There is an extension for mobile communications that determines the transmission of information related to GSM networks (notebook, calendar, call management, digital voice transmission, etc.), between the phone and computers of different sizes (from the desktop to PDA).

These protocols are not exhausted by the entire list of protocols related to IR communications. Note that for remote management of household appliances (TVs, video recorders, etc.) use the same 880-nm range, but other frequencies and physical coding methods.

Transceiver Irda. can be connected to a computer in various ways; With respect to the system unit, it can be both internal (placed on the front panel) and an external placed in an arbitrary place. Placing a transceiver should be based on the angle of "view" (30 ° at the transmitter and 15 ° at the receiver) and the distance to the desired device (up to 1 m).

Internal transceivers At speeds up to 115.2 kbps (IRDA SIR, HP-SIR, ASK IR) Connected through conventional UART chips compatible with 16450/16550 through relatively simple modulator-demodulator schemes. In a number of modern system boards for the use of infrared communication (up to 115.2 kbps), the COM2 port can be configured, for this, in addition to the UART, the chipset contains a modulator and demodulator circuits that provide one or more infrared protocols. To use the COM2 port for infrared, in CMOS Setup. You need to select the appropriate mode (the prohibition of infrared means usual use COM2). There are internal adapters and in the form of expansion cards (for tires ISA, PCI, PC Card), for the system they look like additional Somports.

Specialized microcircuits of controllers are applied on medium and high exchange rates Irda.intensive-oriented software exchange (PIO)or DMA, With the ability to direct bus control. Here, the usual UARC chip is unsuitable because it does not support synchronous mode and high speed. Controller Irda. Fir. It is performed in the form of an extension card or integrate into a system fee; As a rule, such a controller supports and modes SIR.

The transceiver connects to the connector IR-Connector The system board directly (if it is installed on the front panel of the computer) or through the intermediate connector (mini-din), located on the bracket-plug on the rear wall of the case. Unfortunately, there is no single layout of circuits on the inner connector, and for greater flexibility, the transceiver (or intermediate connector) is supplied with cable with separate contacts Connector.

For applied use Irda. In addition to the physical connection of the adapter and the transceiver, installing and configuring the appropriate drivers.

In Windows 9X / ME / 2000, the controller Irda. Enters the "Network Surroundings". Configured software allows

Establish a connection with a local network (to access the Internet, using network resources);

Transmit files between a pair of computers;

Print data;

Synchronize PDA data, mobile phone and desktop computer;

Unload captured images from the camera to the computer and perform a number of other beneficial actions without worrying about what cable farm.

2. Radio interface Bluetooth

Bluetooth (Blue Tooth) is an actual standard for miniature inexpensive information transfer tools for small distances through radio communications between mobile (and desktop) computers, mobile phones and any other portable devices.

The development of the specification is engaged in a troupe of leading firms in the areas of telecommunications, computers and networks - 3com, Agere Systems, Ericsson, IBM, Intel, Microsoft, Motorola, Nokia, Toshiba. This group forms the Bluetooth Special Interest Group and brought this technology to the market. The Bluetooth Specification is freely available on the net (www.blueto6th.com), however, a very thunderist (about 15 MB PDF-Fi-Fi-Fali). The openness of the specification should contribute to its rapid distribution, which is already observed in practice. Here we allow yourself to reduce the name of the technology to "W" (this is an unofficial reduction). The name itself originates from the nickname of the Danish king, which united Denmark and Norway is a hint of a universal combining role of technology.

Transmission is conducted with a cross-bearing frequency with one radio channel to another, which helps in the fight against interference and signal fading. The physical communication channel is represented by a certain pseudo-random sequence of radio channels used (79 or 23 possible frequencies).

A group of devices separating one channel (i.e. knowing the same sequence of the jumps), forms the so-called picoset (Piconet), which can be from 2 to 8 devices.

In each, the picoseti has one leading device and up to 7 active slaves. In addition, in the coverage area of \u200b\u200bthe leading device in its same picoseti may be "parked" slave devices: they also "know" the consistency of the jumps and synchronize (by jumps) with the master, but cannot communicate with the data until the master permits them activity. Each active driven device of the peak has its own temporary number (1-7); When the slave device is deactivated (parked), it gives its number to another. With subsequent activation, it can already get a different number (because it is temporary).

Picoseti can overlap coverage zones by forming a "scattered" "network (Scatternet). At the same time, in each picoseti, the master is only one, but the slave devices can enter several picosets by separating the time (part of the time the device works in one picoseti, part in the other). Moreover, the master of one picoseti can be a driven device of another picotter. These picosetics are not synchronized, each of them uses its channel (consistency of the rear.).

The channel is divided into time slots with a duration of 625 μs, the slots are sequentially numbered with cyclical 2 27. Each time slot corresponds to a single frequency carrier in the rear conquer (1600 of the robs per second). The frequency sequence is determined by the address of the Picotheet Master Device. The transmissions are conducted by packages, each package can occupy from 1 to 5 time slots. If the package is long, then it is all transmitted at one carrier frequency, but the countdown of 625 ISS slots continues, and after a long packet, the next frequency will correspond to the next slot number (that is, several jumps are skipped). The wizard and driven devices lead the transfer alternately: in even slots, the master leads the master, and in odd - the driven device addressed to them (if he has something to say).

Between the master and driven devices, physical connections of two types can be installed: synchronous and asynchronous.

Synchronous connections (they are isochronous) with the establishment of the connection, SCO LINK (Synchronous Connection-Oriented), Used to transmit isochrona graphic (for example, digitized sound). These links type "point-to-point" are pre-installed by a wizard with selected driven devices, and the period (in slots) is determined for each connection, through which slots are reserved for it. Communications are obtained symmetric bilateral. Package re-gear in case of reception errors. The wizard can set up to three SCO connections with one or different slave devices. The slave can have up to three connections with one wizard or have one SCO connection with two different masters. Network classification of SCO communication relate to circuit switching.

Asynchronous connections without establishing a compound , ACL LINK (Asynchronous Connection-Less), Implement switching packages According to the "point-multiple point" scheme between the master and all driven devices of the peak. The wizard can contact any of the driven peak devices in the slots not occupied by SCO, sending him a package and demanding an answer.

1. Wirelessinterfaces

Wireless interfaces allow you to free the devices from binding their interface cables, which is especially attractive for small peripherals, in size and weight commensurate with cables. In wireless interfaces, electromagnetic waves of infrared (IRDA) and radio frequency (Bluetooth) ranges are used. In addition to these interfaces of peripheral devices, there are wireless ways to connect to local networks.

1.1. IRDA infrared interface

The use of emitters and infrared (IR) range receivers allows wireless communication between a pair of devices remote to a distance of up to several meters. Infrared communication - IR (Infra Red) Connection - safe for health does not create interference in the radio frequency range and ensures the privacy of transmission. The IR rays do not pass through the walls, so the reception area is limited to a small, easily controlled space. Infrared technology is attractive to communicate portable computers with stationary computers or docking stations. Infrared interface have some models of printers, they equip many modern small-sized devices: pocket computers (PDA), mobile phones, digital cameras, etc.

There are infrared systems low (up to 115.2 kbps), medium (1.152 Mbps) and high (4 Mbps) speed. Low-speed systems are used to exchange short messages, high-speed - to exchange files between computers, connecting to a computer network, with a printer, projection machine, etc. Expected higher exchange rates, which will allow you to transfer "live video". In 1993, an association of developers of infrared data transmission systems was created Irda. Infrared Data Association) designed to ensure equipment compatibility from various manufacturers. Currently there is a standard Irda. 1.1, along with which their own systems of Hewlett Packard - HP.- Sir. (Hewlett Packard Slow Infra Red) and Sharp - ASK. IR (Amplitude Shifted Keyed IR). These interfaces provide the following transmission speeds:

♦ IRDA SIR (Serial Infra Red), HP-SIR -9.6-115,2 kbps;

♦ IRDA HDLC, known as IRDA MIR (MIDDLE INFRA RED) - 0.576 and 1,152 Mbps;

♦ IRDA FIR (FAST INFRA RED) - 4 Mbps;

♦ ASK IR - 9.6-57.6 Kbps.

Emitter for IR communication is an LED having a peak of the spectral characteristics of the power of 880 nm; The LED gives a cone of effective radiation with an angle of about 30 °. Pin-diodes are used as a receiver, effectively taking IR rays in 15 ° cone. The IRDA specification defines the requirements for the power of the transmitter and the sensitivity of the receiver, and the receiver is given both the minimum and maximum power of IR rays. The pulses of too low power receiver will not "see", and too much power "blinds" the receiver - the received pulses are separated into an indistinguishable signal. In addition to the useful signal to the receiver, interference is affected: the illumination of the solar lighting and incandescent lamps, which gives the constant component of the optical power, and interference with fluorescent lamps, giving a variable (but low-frequency) component. These interference have to filter. The IRDA specification provides bit error levels (Bit Error Ratio, Ber) no more than 10-9 with a range of up to 1 m and daylight (illumination up to 10 keys). Since the transmitter almost inevitably causes the illumination of its own receiver, introducing it into saturation, it is necessary to use a half-duplex connection with certain temporary gaps when changing the exchange direction. For the transmission of signals, binary modulation is used (there is light - no light) and various encoding schemes.

The IRDA specification defines a multi-level protocol system that we consider the bottom up.

The following are options possible at the physical level of IRDA.

♦ Irda. Sir. - for speeds of 2.4-115.2 kbps, a standard asynchronous transmission mode is used (as in som port): start-bit (zero), 8 data bits and stop bits (single). The zero bit value is encoded by a pulse with a duration of 3/16 bite intervals (1.63 μs at a speed of 115.2 kbps), a single - lack of pulses (IRDA SIR-A mode). Thus, in a pause between the parcels, the transmitter does not shine, and each package begins with a start-bit pulse. Specifications 1.1 also also has a different mode -Reda SIR-B, with a fixed pulse duration of 1.63 μs for all these speeds.

♦ ASK. IR - For the speeds of 9.6-57,6 kbps, asynchronous mode is also used, but the encoding is different: zero bit is encoded by sending pulses with a frequency of 500 kHz, single - lack of pulses.

♦ Irda. HDLC - for speeds 0.576 and 1.152 Mbit / s Use synchronous transmission mode and encoding similar to the SIR protocol, but with a pulse duration of 1/4-bit interval. The frame format corresponds to the HDLC protocol, the beginning and end of the frame are marked with flags, inside the frame, this bit sequence is excluded by bits insertion (bit stuffing). To monitor the reliability, the frame contains a 16-bit CRC code.

♦ Irda. Fir. (IRDA4PPM) - Synchronous mode is also used for a speed of 4 Mbps, but the coding is somewhat more complicated. Here, each pair of adjacent bits is encoded by a positional and impulse code: 00 -\u003e 1000, 01 -\u003e 0100, 10 -\u003e 0010,11 -\u003e 0001 (in fours, "1" means the parcel of the pulse in the corresponding quarter of the two-bed interval). This encoding method allowed twice the inclusion frequency of the LED compared to the previous one. The constancy of the average frequency of the receiving pulses facilitates adaptation to the level of external illumination. A 32-bit CRC code is applied to enhance reliability.

Over the physical level is located protocol accessIRLAP. (Irda. Infrared Link Access Protocol) - Modification of the HDLC protocol, reflecting the needs of IR-links. This protocol encapsulates data into frames and prevents conflicts of devices: if there are more than two devices, "seeing" each other, one of them is prescribed primary, and the rest are secondary. Communication is always half duplex. IRLAP describes the procedure for establishing, numbering and closing the compounds. The connection is set at a speed of 9600 bps, after which the metabolism exchange rate is consistent with both both (9,6,19,2,38,4,57,6 or 115,2,2,2,2,2,3,1) and logical channels are installed (each channel Managed by one master device).

Over IRLAP. located connection management protocolIRLmp (Irda. Infrared Link Managment Protocol). With it, the device reports the rest of his presence in the coverage area (the configuration of IRDA devices may vary dynamically: it is enough to reduce the new device to change it or take it away). The IRLMP protocol allows you to detect the services provided by the device, check the data streams and act as a multiplexer for configurations with multiple devices available. Applications using IRLMP can find out if the device required is present in the coverage area. However, this protocol does not provide guaranteed data delivery.

Transport levelprovided by the protocol Tiny TP. (IRDA Transport Protocols) - Virtual channels between devices are served here, errors are processed (lost packages, data errors, etc.), data packaging is packaged in packets and assembly of source data from the packets (the protocol resembles TCP). The IRTP protocol can also work at the transport level.

ProtocolIrcomm. Allows you to emulate the usual wired connection through an IR connection:

♦ 3-wire RS-232C (TXD, RXD and GND);

♦ 9-wire RS-232C (the entire set of SOM port signals);

♦ Centronics (parallel interface emulation).

ProtocolIRLAN. Provides access to local networks, allowing you to transmit ethernet and token Ring network frames. For an IR connection to a local network, a provider is required with an IRDA interface connected by the usual (wired) method to the local network, and the corresponding software support in the client device (which must be logged in).

Object exchange protocolIrbex (Object Exchange Protocol) is a simple protocol that defines the PUT and GET commands to exchange "useful" binary data between devices. This protocol is located above the Tiny Tr. The IROBEX protocol has an extension for mobile communications, which determines the transmission of information related to GSM networks (notebook, calendar, call management, digital voice transmission, etc.), between the phone and computers of different sizes (from the desktop to PDA).

These protocols are not exhausted by the entire list of protocols related to IR communications. Note that for remote management of household appliances (televisions, video recorders, etc.) uses the same range of 880 nm, but other frequencies and physical coding methods.

IRDA transceiver can be connected to a computer different ways; With respect to the system unit, it can be both internal (placed on the front panel) and an external placed in an arbitrary place. Placing a transceiver should be based on the angle of "view" (30 ° at the transmitter and 15 ° at the receiver) and the distance to the desired device (up to 1 m).

Internal transceiversat speeds up to 115.2 kbps (IRDA SIR, HP-SIR, ASK IR) are connected through conventional UART chips compatible with 16450/16550 through relatively simple modulator-demodulator modulator schemes. In a number of modern system boards on the use of infrared communication (up to 115.2 kbps), the COM2 port can be configured. To do this, in addition to the UART, the chipset contains a modulator and demodulator circuits that provide one or more infrared protocols. To use the CMOS SETUP to use the CMOS Setup for infrared in CMOS Setup (the prohibition of infrared communication means the usual use of COM2). There are internal adapters and in the form of extension cards (for ISA, PCI, PC Card); For the system, they look like additional SOM-ports.

In medium and high exchange rates, the specialized IRDA controller chips focused on intensive software-managed exchange or DMA are used, with the possibility of direct bus management. Here, the usual UART transceiver is unsuitable because it does not support synchronous mode and high speed. The IRDA FIR controller is performed as an extension card or integrate into a motherboard; As a rule, such a controller supports SIR modes.

The transceiver connects to the connector IR- Connector Systemicboards directly (if it is installed on the computer's front panel) or through the intermediate connector (mini-din), located on the bracket-plug of the rear wall of the housing. Unfortunately, there is no single layout of chains on the inner connector, and for greater flexibility, the transceiver (or intermediate connector) is supplied with a cable with separate connector contacts. Collect them in due order to provide the user; Options for appointing contacts of the infrared transceiver connector are shown in Table. 1.1. Some transceivers supporting FIR and SIR modes have separate outputs of receivers - IRRX (for SIR) and FIRRX (for FIR). If the controller supports only one of the modes, one of the contacts will remain unconnected.

Table 1.1.Infrared transceiver connector

ChainPurposeContact / option

1 2 3 4

	Entrance from the receiver
	Entrance from the FIR receiver
	Exit to transmitter


	Free

External IR adaptersrelease with RS-232C interface to connect to SOM port or with USB bus. The USB bandwidth is sufficient even for the FIR, the Som port is suitable only for SIR. The external IR IRDA SIR IR adapter for the Som port is not as simple as it would seem: the demodulator modulator requires a synchronization signal with a frequency equal to a 16-fold data transmission frequency (this signal enters the sync chip of the Som-port chip). There is no such signal at the yield of the Som-port and it is necessary to restore it from an asynchronous bitstream. The ASK IR adapter in this regard is simpler - the transmitter must transmit high-frequency pulses all the time until the TXD output is in high condition; The receiver must form envelope adopted pulses.

To applied IRDA, in addition to the physical connection of the adapter and the transceiver, installing and configuring the corresponding drivers. In Windows 9X / ME / 2000, the IRDA controller falls into the Network Surrounding group. Configured software allows you to establish a connection with a local network (to access the Internet, using network resources); transmit files between a pair of computers; print data; synchronize PDA data, mobile phone and desktop computer; Download captured images from the camera to the computer and perform a number of other beneficial actions without worrying about what cable farming.

1.2. Bluetooth radio interface

Bluetooth (Blue Tooth) is an actual standard for miniature inexpensive means of transmitting information using radio communications between mobile (and desktop) computers, mobile phones and any other portable devices for short distances. The development of the specification is engaged in a group of leading firms in telecommunications, computers and network areas - 3COM, Agere Systems, Ericsson, IBM, Intel, Microsoft, Motorola, Nokia, Toshiba. This group forms the Bluetooth Special Interest Group and brought this technology to the market. The Bluetooth Specification is freely available on the net (www.), However, it is quite voluminous (about 15 MB of PDF files). The openness of the specification should contribute to its rapid distribution, which is already observed in practice. Here we allow yourself to reduce the name of technology to "W" (this is not an official reduction). The name itself is a nickname of the Danish king, united by Denmark and Norway, is a hint of a universal combining role of technology.

Each WP device has a radio transmitter and receiver operating in the frequency range of 2.4 GHz. This range in most countries is assigned to industrial, scientific and medical equipment and does not require licensing, which ensures the widespread applicability of devices. For W, radio channels are used with discrete (binary) frequency modulation, carrier frequency of channels F \u003d 2402 + K (MHz), where k \u003d 0 ... 78. For several countries (for example, France, where military operating in this range) is possible a reduced variant with F-2454 + K (K-0 ... 22). The coding of a simple - logical unit corresponds to the positive frequency deviation, zero - negative. Transmitters can be three power classes, with a maximum capacity of 1, 2.5 and 100 MW, and the possibility of lowering the power in order to save energy. Transmission is conducted with a cross-bearing frequency with one radio channel to another, which helps in the fight against interference and signal fading. Physical channelcommunications seems to be a specific pseudo-random sequence of radio channels used (79 or 23 possible frequencies). A group of devices separating one channel (that is, the "knowledgeable" one and the same sequence of the jumps) forms the so-called picoset(Piconet), which can be from 2 to 8 devices. Each picosette has one leading device and up to 7 active slaves. In addition, in the coverage area of \u200b\u200bthe leading device in its same picoseti may be "parked" slave devices: they also "know" the sequence of the jumps and synchronize (by jumps) with the master device, but cannot communicate with the data until the leading device is not Allow their activity. Each active driven device of the peak has its own temporary number (1-7); When the slave device is deactivated (parked), it gives its own number to use by others. When subsequent activation, it can already get a different number (because it is temporary). Picoseti can overlap coverage zones by forming a "scattered" network (Scatternet). At the same time, in each picoseti, the master device is only one, but the slave devices can enter several piquettes using the time separation (part of the time it works in one, part is in another picoseti). Moreover, the leading device of one picotter can be the driven device of another picotter. These picosetics are not synchronized, each of them uses its channel (consistency of the rear.).

The channel is divided into time-slots with a duration of 625 X, the slots are sequentially numbered with cyclicality 227. Each time slot corresponds to one frequency carrier in the rear-line sequence (1600 per second). The frequency sequence is determined by the address of the leading device of the peak. The transmissions are conducted by packages, each package can occupy from 1 to 5 time slots. If the package is long, then it is passed on one frequency of carrier, but the countdown of 625 ISS slots continues, and after a long packet, the next frequency will correspond to the next slot number (that is, several jumps will be skipped). The drive and driven devices lead the transfer alternately: in even slots, the transmission leads the leading device, and in the odd - the driven device addressed to them (if it is what "say").

The physical connections of two types can be installed between the leading and driven devices: synchronous and asynchronous.

Synchronous connections(They are isochronny) with establishing a connection, SCO Link (Synchronous Connection-Oriented) are used to transmit isochronous traffic (for example, digitized sound). These links of the "point-to-point" type pre-set the master device with selected driven devices, and for each connection the period (in slots) is determined through which slots are reserved for it. Communications are obtained symmetric bilateral. Repeated packet transmission in case of reception errors are not used. The master can be installed up to three SCO connections with one or different slave devices. The slave can have up to three connections with one master device or have one SCO connection with two different leading devices. Network classification of SCO communication relate to circuit switching.

Asynchronous connectionswithout establishing a connection, ACL Link (asynchronous Connection-Less) implements switching packagesaccording to the "point-multiple point" scheme between the leading device and all the driven devices of the picoseti. The master can be associated with any of the driven peak devices in slots not occupied by SCO, sending a package to him and demands an answer. The slave device has the right to transfer, only receiving the driver request addressed to it (unmistakably decoding its address). For most types of packages, retransmission is provided if the reception error is detected. The drive device can send both non-aligned broadcast packets for all driven devices of their picoseti. With each of their driven devices, the master can be installed only one ACL connection.

Information is transmitted by packets in which the data field may have a length of 0-2745 bits. For connectionsACL There are several types of packets with a CRC code protection (if an error is detected, re-transmission is provided) and 1 defenseless (without repeat gear). For connectionsSCO. The data is not protected by the CRC code, and therefore repeated transmissions on the reception error are not provided.

Protection of data from distortion and monitoring of reliability is made in several ways. The data of some types of packages are protected by the CRC code, and the information receiver must confirm the reception of the correct package or report acceptance error. To reduce the number of repetitions, excess encoding FEC (Forward Error Correction Code) is applied. In the FEC 1/3 scheme, each useful bit is transmitted three times, which allows you to choose the most believable majority option. The FEC 2/3 scheme is somewhat more complicated, it uses the Hamming code here, which allows you to correct all one-time and detect all double errors in each 10-bit block.

Everyone voice channelprovides a speed of 64 kbps in both directions. The Channel can use coding in PCM format (pulse-code modulation) or CVSD (Continuous Variable Slope Delta Modulation - version of the adaptive delta of the pulse-code modulation). RSM encoding allows compression by G.711; It provides only a purely "telephone" signal quality (meaning digital telephony, 8-bit samples with a frequency of 8 kbps). CVSD encoder provides higher quality - it packs the input RSM signal with a frequency of samples 64 kbps, however, the spectral density of the signal in the frequency band of 4-32 kHz must be insignificant. To transmit a high-quality audio signal voice (voice) WW channels are unsuitable, however, a compressed signal (for example, a MPZ flow) can be passed on an asynchronous data channel.

Asynchronous canalit can provide a maximum speed of 723.2 kbps in an asymmetric configuration (leaving for the reverse channel of the band 57.6 kbps) or 433.9 kbit / s in each direction in a symmetrical configuration.

To ensure security in W authenticationand cipherdataat the level of communication (Link Layer), which, of course, can be complemented by the means of the upper protocol levels.

An important part of W is services detection protocolSDP. (Service Discovery Protocol), allowing the device to find a "interesting interlocutor". In the future, setting the connection with it, the device will be able to use the required services (for example, to display documents for printing, connect to the network, etc.).

ProtocolRFComm. Provides the serial port emulation (9-wire RS-232) via L2CAP. With its help, traditional cable connections of devices (including zero-modem) can be easily replaced with radio communication, without any modifications at the upper levels. The protocol allows you to install and multiple connections (one device with several), and radio communication will replace bulky and expensive multiplexers and cables. Through the RFComm protocol, the sheeter used in infrared wireless connections can operate (in the IRDA hierarchy), the RWP protocol and the RW protocol can also work on which the TCP / IP stack protocols are standing - it opens the road to all applications for the Internet. Through RFComm, the AT-commands, controlling telephone connections and fax transmission services (the same commands are used in modems for switched lines). Special bit-oriented telephone protocolTCS BIN (TELEPHONY CONTROL PROTOCOL - BINARY), defining a call signaling to communicate WT devices (voice communications and data exchange), also works through L2CAP. The protocol has both TCS device groups.

Host controller interfaceHCI Host Controller Interface is a uniform access method to the low levels of the low levels of W. It provides a set of commands to manage radio communications, obtain information about the status and data transmission itself. Through this interface, the L2CAP protocol is interacted with WP equipment. Physically, WT can connect to various interfaces: extension bus (for example, PC Card), USB bus, SOM port. For each of these connections, there is an appropriate HCI transport link protocol - a layer providing HCI independence from the connection method.

2. Serial tiresUSB andFire Wire.

Serial tires allow you to combine multiple devices using only 1-2 pairs of wires. The functionality of these tires is much wider than that of traditional local network interfaces, the USB and FireWire can transmit isochronous traffic audio and video data. Sequential tires in their organization are very different from parallel. In serial tires there are no individual lines for data, addresses and controls - all protocol functions have to be performed using one or two (in FireWire) steam of signal wires. This imposes an imprint on the construction of a bus protocol, which in consecutive tires is based on shipments packets- in certainly organized bit chains. Note that in USB terminology, packets and frames have a slightly different interpretation than in data networks. In parallel tires, there are possibilities for explicit synchronization of the interface part of the leading and slave devices; The execution of each sharing of the exchange protocol can be confirmed, and, if necessary, some sharing phases can be extended by the "request" of the non-successive device. In consecutive tires there is no such possibility - the package is sent entirely, and the synchronization is possible only on the bits received. These and other features bring consecutive tires with local data networks.

USB and FireWire tires have the greatest popularity, although the latter is still used in PC compatible computers everywhere. FireWire and USB serial tires, having common features, are nevertheless substantially various technologies. Both tires provide a simple connection of a large number of PU (127 for USB and 63 for FireWire), switching switching and turning on / off the devices during the operating system. According to the structure, the topology of both tires is quite close, but FireWire allows greater freedom and spatial length. USB hubs are part of many devices and their presence is often unnoticed. Both tires have devices power lines, but permissible power for FireWire is significantly higher. Both tires support PNP technology (automatic configuration when switching on / off) and remove the problem of address deficit, DMA channels and interrupts. Available bandwidth and tire management.

TireUSB Oriented on peripheralsconnected to PC. USB isochronous transmissions allow you to transmit digital audio signals, and USB 2.0 bus is capable of carrying and video data. All transmissions are controlled centrally, and the PC is a necessary control unit located in the root of the tree of the tire. USB adapter users of modern PCs are obtained almost free because it is part of all the modern chipsets of motherboards. True, USB 2.0 adapters will be released in the form of PCI cards. The direct connection of multiple PC bus USB is not provided, although "active cables" are available to communicate computers and hubs.

TireFirewire. Focused on devices household electronicswhich with its help can be combined into a single home network. A computer can be connected to this network, and not even one. The principal advantage of the tire 1394 is the lack of need for a special tire controller (computer). Any transmitting device can get a band of isochronous traffic and start transmission by autonomous signal or remote control - Receivers will "hear" this information. In the presence of the controller, the appropriate software can control the operation of the devices, implementing, for example, a digital studio of a nonlinear video editing or providing the required multimedia data of all interested information consumers.

2.1. USB bus

USB (Universal Serial Bus - Universal Serial Tire) is an industrial standard for expanding the PC architecture oriented with telephony and telephones and appliances of consumer electronics. Version 1.0 was published in early 1996, most devices supported version 1.1, which came out in the fall of 1998, "the foundations found were eliminated in it. In the spring of 2000, a USB 2.0 specification is published, in which 40x bandwidth tires. Initially (in versions 1.0 and 1.1) the tire provided two speeds of information transfer: complete speedFS. (Full Speed) - 12 Mbps and low speedLs. (Low Speed) - 1.5 Mbps. In version 2.0 also defined and high speedHS. (High Speed) - 480 Mbps, which allows you to significantly expand the circle of devices connected to the bus. In the same system, devices with all three speeds can also be opened. The tire using intermediate hubs allows you to connect devices deleted from the computer to a distance of up to 25 m. Detailed and operational information on USB (in English) can be found at http: // www. USB. Org.

Bluetooth "W" (blue tooth) - This is the actual standard for miniature inexpensive means of transmitting information for small distances through radio communications between mobile (and desktop) computers, mobile phones and any other portable devices.

The development of the specification is engaged in a group of leading firms in the regions of telecommunications, computers and networks - 3Com, Agere Systems, Ericsson, IBM, Intel, Microsoft, Motorola, Nokia, Toshiba. This group formed Bluetooth Special Interest GroupAnd brought this technology to the market. The Bluetooth Specification is freely available online.

Transmitters can be three power classes, with a maximum power of 1, 2.5 and 100. MW, and the possibility of lowering the power in order to save energy. Transmission is conducted with a cross-bearing frequency with one radio channel to another, which helps in the fight against interference and signal fading. Physical canal Communications seems to be a specific pseudo-random sequence of radio channels used (79 or 23 possible frequencies).

A group of devices separating one channel (i.e. knowing the same consistency), forms the so-called piconeet (Piconet)which can be from 2 to 8 devices.

In each, the picoseti has one leading device and up to 7 active slaves. In addition, in the coverage area of \u200b\u200bthe leading device in its same picoseti may be "parked" slave devices: they also "know" the consistency of the jumps and synchronize (over the jumps) with the master, but cannot communicate with the data until the master permits them Activity. Each active driven device of the peak has its own temporary number (1-7); When the slave device is deactivated (parked), it gives its number to another. When subsequent activation, it can already get different.

Between the master and driven devices, physical connections of two types can be installed: synchronous and asynchronous.

Synchronous connections (they are isochronny) with the establishment of the connection, SCO LINK (Synchronous Connection-Oriented)used to transmit isochrona graphics (for example, digitized sound). These "point-to-point" links are pre-installed by a wizard with selected driven devices, and the period (in slots) is determined for each connection, through which slots are reserved for it. Communications are obtained symmetric bilateral. Package re-gear in case of reception errors. The wizard can set up to three SCO connections with one or different slave devices. The slave can have up to three connections with one wizard or have one SCO connection with two different masters. On network classification of SCO communication relate to circuit switching.

Asynchronous connections without establishing a connection, ACL LINK (Asynchronous Connection -less), We implement switching packets according to the "point-set point" scheme between the Master and all the driven peaks. The wizard can contact any of the driven peak devices in the slots not occupied by SCO, sending him a package and demanding an answer.

The slave device has the right to transfer, only having received a wizard request addressed to it (unmistakably decoding his address). For most types of packages, retransmission is provided if the reception error is detected. The wizard can send both beased broadcast packets for all driven devices of their picoseti. With each of their driven devices, the wizard can install only one ACL connection.

Wi-Fi

Wi-Fi (eng. Wireless Fidelity - "Wireless Accuracy") - Standard on Wireless LAN equipment.

Developed by the Wi-Fi Alliance Consortium based on iEEE standards 802.11 .

Typically, the Wi-Fi network scheme contains at least one access point and at least one client. It is also possible to connect two clients in point-point mode when the access point is not used, and clients are connected via network adapters "directly". Access point will transmit its network identifier ( SSID) Using special signal packets at a speed of 0.1 Mbps every 100 ms. So 0.1 Mbps - the smallest transmission speed data for Wi-Fi. Knowing SSID Networks, the client can find out if connecting to this access point is possible. If you get into the zone of action of two access points with identical SSIDThe reception can choose between them based on the signal level data.

Benefits Wi-Fi

Allows you to deploy a network without a cable laying, it can reduce the cost of the wave and expansion of the network. Places where the cable cannot be paved, for example, outdoors and in buildings with historical value can be serviced by wireless networks.

Discharge Wi-Fi

Frequency range and operational restrictions in different countries of unequal.
High energy consumption
May be relatively easy to hacked /
Wi-Fi limited range radius. The home router Wi-Fi has a range of 45 m indoors and 90 m outside. (Microwave or mirror located between Wi-Fi devices weaken the signal level. The distance depends also on the frequency. Reducing the network performance during rain.

Note In the US, the 2.5 GHz range is allowed to use without a license, provided that the power does not exceed a certain amount, and such use does not create interference to those who have a license.

In Russia, the use of Wi-Fi without permission to use frequencies from the state commission on radio frequencies (GCRC) is possible to organize a network inside buildings, closed warehouses and industrial areas. For legal use of non-optical wireless wi-Fi network (for example, a radio channel between two neighboring houses) it is necessary to obtain permission to use frequencies. There is a simplified procedure for issuing permits for the use of radio frequencies in the band 2400-2483.5 MHz.

Lan.

Local computing network (LAN, local network; (eng. Local Area Network, LAN - computer network Covering usually relatively small territory or a small group of buildings (home, office, firm, institute).

Peripheral devices using LAN connections can be connected with each other using various copper conductors (