chapter 7_computer peripherals

8/9/2019 Chapter 7_computer Peripherals

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COMPUTER PERIPHERALSCOMPUTER PERIPHERALSVIDEO CARDVIDEO CARDVOICE CARDVOICE CARD

MODEM AND FAXMODEM AND FAX

PREPARED BY : MOHD FADHIL BIN RAMLE


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WHAT IS ADAPTER CARD?WHAT IS ADAPTER CARD?

a circuit board installed in computer toincrease the capabilities of that computer.The card must be match to the bus type

of the motherboard (example : install aPCI network card only into a PCI

expansion slot).


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VIDEO CARDVIDEO CARD

Commonly called video card.To allow the computer to display information on

some kind of monitor or LCD display.Responsible to converting the data sent to it by

the CPU into the pixels, addresses and otheritems required for display.

Sometimes, video cards can include dedicatedchips to perform certain of these functions, thus

accelerating the speed of display.With todays motherboard, most video cards are

AGP and, with increasing popularity, PCIeexpansion cards that fit in the associated slot ona motherboard.


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History of video-display technology: MDA (Monochrome Display Adapter). HGC (Hercules Graphics Card)

CGA (Color Graphics Adapter) EGA (Enhanced Graphics Adapter) VGA (Video Graphics Array) SVGA (Super VGA) XGA (Extended Graphics Array)

MDA, HGC, CGA, EGA or MCGA was obsolete.All current display adapter that connect to

the 15-pin VGA analog connector or the DVIanalog/digital connector are based on theVGA standard.

VIDEO DISPLAY ADAPTOR


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Unlike earlier video standards, which aredigital, VGA is an analog system.

Most personal computer displays introducedbefore the PS/2 are digital.This type of display generates different colors

by firing the RGB electron beams in on-or-offmode, which allows for the display of up toeight colors (23). In the IBM displays andadapters, another signal doubles the numberof color combinations from 8 to 16 bydisplaying each color at one of two intensity

levels.



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Digital display is easy to manufacturer and offers simplicitywith consistent color combination from system to system.

The real drawback of the older digital displays such as CGA

and EGA is the limited number of possible colors. In the PS/2 system, IBM went to analog display circuit (April

2, 1987). Analog displays work like the digital displays but each color

in the analog display system can be displayed at varying

levels of intensity-64 levels, in the case of VGA. So, analog system provide 262,144 possible colors (643) of

which 256 could be simultaneously displayed. For realistic computer graphics, color depth is often more

important than high resolution because the human eye

perceives a picture that has more colors as being morerealistic.



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Video Graphic ArrayVideo Graphic Arraya purely IBM-defined standard

VGA BIOS is the control software residing in thesystem ROM for controlling VGA circuits.

The VGA can run almost any software thatoriginally was written for the CGA or EGA.

A standard VGA card displays up to 256 colors

onscreen, from a palette of 262,144 (256KB)colors; when used in the 640x400 text mode, 16colors at a time can be displayed.

Because the VGA outputs an analog signal, youmust have a monitor that accepts an analoginput.



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Also come in monochrome VGA models.64 gray shades are displayed instead of

colors.Uses an algorithm that makes the desired

color and rewrites the formula to involve

all three color guns, producing varyingintensities of gray.



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Super VGASuper VGAwas defined by the Video Electronics

Standards Association (VESA)In that first version, it called for a

resolution of 800 600 4-bit pixels (Each

pixel could therefore be any of 16different colours).extended to 1024 768 8-bit pixels, and

well beyond that in the following years.



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SVGA uses a VGA connector (DE-15)
http://upload.wikimedia.org/wikipedia/commons/9/92/SVGA_port.jpg


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Integrated Video/Motherboard ChipsetsIntegrated Video/Motherboard ChipsetsThe performance and features of built-in

video differed only slightly from add-oncards using the same or similar chipsets.



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Integrated Video Features of Intel 8xxChipsets


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Table 15.9Table 15.9


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All video adapters contain certain basiccomponents, such as the following:

Video BIOS Video processor/video accelerator

Video memory

Digital-to-analog converter (DAC).

Bus connector Video driver

VIDEO DISPLAY ADAPTOR COMPONENTS


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VIDEO CARDVIDEO CARDVIDEO DISPLAY ADAPTOR COMPONENTS


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VIDEO BIOSVIDEO BIOSContaining basic instructions that provide an interface

between the video adapter hardware and the softwarerunning on your system.

Enables your system to display information on themonitor during the system POST and boot sequences.

Can be upgraded (use EEPROM).

Video BIOS upgrades (sometimes referred asfirmware upgrades) are sometimes necessary in orderto use an existing adapter with a new operatingsystem or when manufacturer encounters asignificant bug in original programming.



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VIDEO PROCESSORVIDEO PROCESSORThe heart of any video adapter and essentially defines

the cards functions and performance levels.Two video adapters with the same chipset often have

the same capabilities and deliver comparableperformance.

Software drivers that OS and applications use to

address the video adapter hardware are writtenprimarily with the chipset.The video adapter that use the same chipset may

differ in the amount and type of memory installed.



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VIDEO CARDVIDEO CARDVIDEO DISPLAY ADAPTOR COMPONENTS


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VIDEO AND SYSTEM CHIPSETSVIDEO AND SYSTEM CHIPSETSWhy you should find out which chipset the

video card or video circuit use?: Better comparisons of card or system to others

Access to technical specifications

Access to reviews and opinions

Better buying decisions

Choice of card manufacturer or chipsetmanufacturer support and drivers.



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Video RAMVideo RAMmost video adapters rely on their own onboard

memory to store video images while processingthem

Size : 32MB, 64MB or more of onboard memory.Many low-cost system with onboard video use

the universal memory architecture (UMA) featureto share the main system memory.

Memory on the video card or borrowed from thesystem performs the same tasks.



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Video RAMVideo RAMAmount of memory on the adapter or used by

integrated video determines the maximumscreen resolution and color depth the device cansupport.

Common memory size : 32MB, 64MB and

128MB.Adding more memory is not guaranteed to speed

up your video adapter.Speed can increase if it enables a wider bus

(from 64bits wide to 128bits wide) or providenondisplay memory as a cache.



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Video RAMVideo RAMSGRAM, SDRAM, DDR and DDR-II SDRAM have

replaced VRAM, WRAM and MDRAM as highspeed solutions.



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SDRAMSDRAMSynchronous DRAM

Usually surface mounted individual chips; on a fewearly models, a small module containing SDRAMsmight be plugged into proprietary connector.

Designed to work with bus speeds up to 200MHz andprovides performance just slightly slower than

SGRAM.Used in current low-end video cards and chipsets

such as NVIDIAs GeForce2 MX and ATIs RADEONVE.



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SGRAMSGRAMSynchronous Graphics RAM (SGRAM).

High-end solution for very fast video adapterdesigns.

Differs from SDRAM by including circuitry toperform block writes to increase the speed of

graphics fill or 3D Z-buffer operations.Although SGRAM is faster than SDRAM, most

video card makers dropped SGRAM in favor ofeven faster DDR-SRAM in their newest products.



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DDR SDRAMDDR SDRAMDouble Data Rate SDRAM.

Designed to transfer data at speeds twice that ofconventional SDRAM by transferring data on boththe rising and falling parts of the processing clockcycle.

Todays mid-range and low-end video cardsbased on chipsets such as NVIDIAs GeForce FXand ATIs RADEON 9xxx series use DDR SDRAMfor video memory.



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DDR-II SDRAMDDR-II SDRAMSecond generation of DDR SDRAM.

Fetches 4 bits of data per cycle, instead of 2 aswith DDR SDRAM (double performance at thesame clock speed).

First video chipset to support DDR-II was

NVIDIAs GeForce FX.



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GDDR-3 SDRAMGDDR-3 SDRAMBased on DDR-II memory with two major

differences: GDDR-3 separates reads and writes with a single-ended

unidirectional strobe, whereas DDR-II uses differentialbidirectional strobes. This method enables much higherdata transfer rates.

GDDR-3 uses an interface technique known aspseudo-open drain, which uses voltage instead of current. Thismethod makes GDDR-3 memory compatible with GPUsdesigned to use DDR or DDR-II memory.



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VIDEO RAM SPEEDVIDEO RAM SPEEDVideo cards with same type 3D graphics

processor chip (GPU) onboard might use differentspeeds of memory.

Example: Two cards use the NVIDIA GeForce FX 5200-the Prolink

PixelView (4ns memory) and the Chaintech A-FX20 (5nsmemory)-use different memory speeds.

Sometimes, video makers also match different memoryspeeds with different versions of the same basic GPU, aswith ATIs Radeon 9800 XT and 9800 Pro: 9800XT has acore clock speed of 412MHz versus the 9800 Pros

380MHz clock speed.



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RAM CALCULATIONSRAM CALCULATIONSTo find amount of memory a video adapter needs to

display a particular resolution and color depth.Resolution determines the number of total pixels. For

example, a screen resolution of 1024x768 requires atotal 786,432 pixels.

If you were to display that resolution with only two

colors, you would need only 1 bit of memory space torepresent each pixel.(0=dot is black, 1=dot is white)

If you use 24 bits of memory space to control eachpixel, you can display more than 16.7 million colors(224 )



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Amount of memory that adapter needs to display thatresolution.

1024x768 = 786432 pixels x 24 bits per pixels

= 18,874,368 bits

= 2,359,296 bytes

= 2.25 MB

Because most adapters support memory amounts ofonly 256KB, 512KB, 1MB, 2MB or 4MB. You wouldneed to use video adapter with at least 4MB of RAMonboard to run your system using that resolution andcolor depth.



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VIDEO CARDVIDEO CARDVIDEO DISPLAY ADAPTOR


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DIGITAL-TO-ANALOG CONVERTERDIGITAL-TO-ANALOG CONVERTERCommonly called a RAMDAC

Convert the digital images your computer generatesinto analog signals the monitor can display.

Measured in MHz, the higher vertical refresh rates,allow higher resolutions with flicker-free refresh rates(72Hz-85Hz or above)

Typically, cards with RAMDAC speeds of 300MHz orabove display flicker-free at resolutions up to1920x1200.

Of course, you must ensure that any resolution youwant to use is supported by both your monitor andvideo card.



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THE BUSTHE BUSIBM

MCAISAEISA

VL-BusPCIAGPPCI-eXPRESS


OBSOLETE


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THE BUSTHE BUS

AGPDeliver maximum bandwidth up to 16times

larger PCIEnhancement to PCI bus.Use with only video adapter

Provides high-speed access to the main systemmemory array.

Four speed of AGP



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THE BUSTHE BUS

PCI EXPRESS Succeed both AGP and PCI Use high speed bidirectional serial data transfer method. PCI Express channels (also known as lanes) can be

combine to create wider and faster expansion slots (eachlanes provides 250MBps data rate in each directional).

Unlike PCI bus, PCI Express do not compete with eachother for bandwidth.

PCI Express graphics cards use 16 lanes (x16) to enablespeeds of 4GBps in each direction.

When PCI Express used for other types of cards, fewer

lanes are used.



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THE VIDEO DRIVERTHE VIDEO DRIVERDriver enables your software to communicate

with the video adapter.Video drivers are designed to support the

processor on the video adapter.Provide the interface you can use to configure

the display your adapter produces.Video driver: get from supplied disk from card

manufacturer or from chipset maker.Sometimes you might find that one of the

provides better performance than the other.



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HOW 3D ACCELERATORS WORKHOW 3D ACCELERATORS WORKTo construct an animated 3D sequence, a

computer can mathematically animate thesequences between keyframes.

Example: a bouncing ball can have threekeyframes; up, down, and up. Using this frames as a reference point, the computer can

create all the interim images between the top andbottom.

After creating the sequence, the system can then refinethe appearance of the images by filling them in color.

Flatshading: shape is filled with a solid color.

Gouraud shading: colors to specific points on a shape.



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HOW 3D ACCELERATORS WORKHOW 3D ACCELERATORS WORK3D software convert image abstractions into the fully

realize images that are then displayed on the monitor.

The image abstractions typically consist of the followingelements:

Vertices: location of objects in three-dimensional space,described in terms of their x, y and z coordinates on threeaxes representing height, width and depth.

Primitives: the simple geometric objects the application usesto create more complex construction, describe in terms of therelative locations of their vertices.

Textures: two-dimensional bitmap images or surfacesdesigned to be mapped onto primitives. The softwareenhances the 3D effect by modifying the appearance of the

textures.



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AUDIO ADAPTERAUDIO ADAPTER


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BASIC CONNECTORSBASIC CONNECTORS

Rear out or speaker/headphone connector (no

standard color)Older sound cards often provided an amplifiedjack supplying up to 4 watts of power for usewith unpowered speakers or headphones along

with the line-out connector.Today, this jack used for rear speakers in four-

speaker setups.

AUDIO ADAPTOR


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BASIC CONNECTORSBASIC CONNECTORS

Microphone, or mono, in connector (pink)

Used to connect a microphone for recording yourvoice or other sounds to disk.

Record in mono and not suitable for high-qualitymusic recording.

Use Automatic Gain Control (AGC) to improverecordings, this feature adjust the recordinglevels on-the-fly.

A 600ohm-10,000ohm dynamic or condenser

microphone works best with this jack.

AUDIO ADAPTOR


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BASIC CONNECTORSBASIC CONNECTORSGame port (gold)

Also called joystick connector 15-pin D-shaped connector that can connect to any

standard joystick or game controller.

MIDI connector (gold)

Audio adapters typically use the same joystick port as theirMIDI connector.

Two of the pins in connector are designed to carry signalsto and from a MIDI device, such as electronic keyboard.

AUDIO ADAPTOR


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CONNECTORS FOR ADVANCED FEATURESCONNECTORS FOR ADVANCED FEATURESMIDI in and MIDI out

Some advanced sound card dont require you to convert thegame port (joystick port) to MIDI interfacing. Offering this ports on a separate external connector. Typical location: external device.

SPDIF in and SPDIF out. Sony/Philips Digital interface receives digital audio signals

directly from compatible devices without converting them toanalog first.

Typical location: external device (also referred as DolbyDigital interfaces.)

AUDIO ADAPTOR


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CONNECTORS FOR ADVANCED FEATURESCONNECTORS FOR ADVANCED FEATURESCD SPDIF

Connects compatible CD-ROM drives with SPDIF interfacingto the digital input of the sound card. Typical location: side of audio card

TAD in

Connects internal modems with Telephone AnsweringDevice support to the sound card for sound processing ofvoice message.

Typical location: side of audio card

AUDIO ADAPTOR


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CONNECTORS FOR ADVANCED FEATURESCONNECTORS FOR ADVANCED FEATURESDigital DIN out

This supports multispeaker digital speaker systems, suchas those produced by Cambridge for use with SoundBlasterLive! Series.

Typical location: side of audio card.

Optical SPDIF in/out This supports home theater and digital speaker system

with optical inputs. Typical location: rear of card or external device.

AUDIO ADAPTOR


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CONNECTORS FOR ADVANCED FEATURESCONNECTORS FOR ADVANCED FEATURESAux in

Provides input for other sound sources, such as a TV tunercard. Typical location: side of audio card.

I2S in Enables the sound card to accept digital audio input from

an external source, such as two-channel decoded AC-3from DVD decoders and MPEG-2 Zoom Video Typical location: side of audio card

AUDIO ADAPTOR


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CONNECTORS FOR ADVANCED FEATURESCONNECTORS FOR ADVANCED FEATURESUSB port Enables the sound card to connect to USB speakers, game

controllers and other types of USB devices. The Hercules GameTheater XP Series, the first sound card with built in USB ports,supports USB 1.1 only.

Typical location: external breakout box

IEEE 1394 this enables the sound card to connect to IEEE 1394-compatible

DV camcoders, scanner, hard drives and other devices. Creative Labs Sound Blaster Audigy, Audigy 2 series and Hercules

Digifire 7.1 all feature one or nore IEEE 1394. Typical location: card bracket or external cable or breakout box.

AUDIO ADAPTOR


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CONNECTORS FOR ADVANCED FEATURESCONNECTORS FOR ADVANCED FEATURESFigure 16.3

Figure 16.4

AUDIO ADAPTOR


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AUDIO ADAPTER CONCEPTS AND TERMSAUDIO ADAPTER CONCEPTS AND TERMSThe Nature of Sound

Every sound is produced by vibrations that compress air orother substances. Two of the basic properties of any sound are pitch and

intensity. Pitch

rate at which vibrations are produced.

Measure in the number of hertz (Hz) or cycle per second.

Higher the frequency the higher the pitch.

Intensity Called amplitude

Determine the sounds volume and depends on the stength ofthe vibrations producing the sound.

AUDIO ADAPTER CONCEPTS AND TERMS


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AUDIO ADAPTER CONCEPTS AND TERMSAUDIO ADAPTER CONCEPTS AND TERMSEvaluating the Quality of Your Audio Adapter

Quality of audio adapter is often measured by the threecriteria

Frequency response (or range)

Total harmonic distortion

Signal-to-noise ratio.

Frequency Response

Range in which an audio system can record or play at aconstant and audible amplitude level.

Many cards support 30Hz-20kHz.

Wider the spread better the adapter.



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Signal-to-noise ratio (S/N or SNR) Measures the strength of the sound signal relative tobackground noise (hiss).

Higher the number (measured in decibels), the better thesound quality.

For example: the top-of-the-line Sound Blaster Audigy 2 sound

card features an SNR of 106db, whereas the older SoundBlaster Audigy is rated at 100db.

These factors affect all types of audio adapter use, fromWAV file playback to speech recognition.

Low-quality microphones and speakers can degrade the

performance of a high-quality sound card.



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Quality of audio adapter is often measured by the threecriteria

Frequency response (or range)

Total harmonic distortion

Signal-to-noise ratio.

Frequency Response

Range in which an audio system can record or play at aconstant and audible amplitude level.

Many cards support 30Hz-20kHz.

Wider the spread better the adapter.



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AUDIO ADAPTER CONCEPTS AND TERMSAUDIO ADAPTER CONCEPTS AND TERMSSampling

With an audio adapter, a PC can record waveform audio.Waveform audio : sampled or digitized sound. Analog-to-digital converters (ADCs) convert analog sound

waves into digital bits that the computer can understand. Digital-to-analog converters (DACs) convert the recorded

sounds to an audible analog format. Sampling is the process of turning the original analogsound waves into digital (binary) signals that the computercan save and later replay.

The system samples the sound by taking snapshots of itsfrequency and amplitude at regular intervals.



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AUDIO ADAPTER CONCEPTS AND TERMSAUDIO ADAPTER CONCEPTS AND TERMS

Figure 16.7Figure 16.7



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MODEMSMODEMS


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WHAT IS MODEMWHAT IS MODEM

a device that modulates an analog carriersignal to encode digital information, and

also demodulates such a carrier signal todecode the transmitted information.


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HOW MODEMS AREHOW MODEMS ARE

CLASSIFIEDCLASSIFIED

Modems are generally classified by: amount of data they can send in a given time,

normally measured in bits per second (bit/s, orbps).

the number of times the modem changes itssignal state per second (Baud).


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MODEM PROTOCOLSMODEM PROTOCOLS

All modems support the following ITUprotocols:

ITU V.90 (modulation) ITU V.42 (error correction)

ITU V.42bis (data compression)


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BITs AND BAUD RATESBITs AND BAUD RATES

BITs

the number of bits that are conveyed or processed perunit of time.

Unit ; bps or Kbps

Baud rates

Is a signaling rate, not a data-transmission rate.

Eg: if a signal between two modems can changefrequency or phase at a rate of 300 times per second,the device is said to communicate at 300 baud.


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MODULATION STANDARDSMODULATION STANDARDS

Three most popular modulation methods: frequency-shift keying (FSK)

phase-shift keying (PSK). Quadrature amplitude modulation (QAM)


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Frequency-shift Keying (FSK)Frequency-shift Keying (FSK)

A form of frequency modulation,otherwise known as FM. By causing and

monitoring frequency changes in a signalsent over the phone line, two modem cansent information.


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Frequency-shift Keying (FSK)Frequency-shift Keying (FSK)


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Phase-shift Keying (PSK).Phase-shift Keying (PSK).

is a digital modulation scheme thatconveys data by changing, or modulating,

the phase of a reference signal (thecarrier wave).


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Quadrature amplitude modulationQuadrature amplitude modulation

(QAM)(QAM)

conveys two analog message signals, ortwo digital bit streams, by changing

(modulating) the amplitudes of two carrierwaves, using the amplitude-shift keying(ASK) digital modulation scheme oramplitude modulation (AM) analog

modulation scheme.


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MODEMMODEM

All modem protocols since ITU V.34 (33.6Kbpsmaximum speed) up through the current ITU V.90and ITU V.92 standards (56Kbps maximum speed)

are full-duplex protocols.ITU V.90 and V.92 protocols are the industry-

standard protocols used today; V.92 support V.90.Full-duplex: communications can travel in both

directions at the same time and at the same speed.example: telephone call.

Half-duplex: communications can travel in bothdirections, but only one side can transmit at a time.

example: radio call.


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MODEMMODEM

V.90 V.90 is the ITU-T designation for a 56Kbps communication

standard.

Reconciles the conflict between the proprietary U.SRobotics (3Com) x2 and Rockwell K56flex modemspecifications developed in 1996 and 1997.

The last ISA modems manufactured by major vendorstypically support V.90, as do many PC Card and PCI

modems built from 1998 to 2001.V.92 Improved version of V.90 standard. Provide faster negotiation of the connection, call waiting

support and faster uploading than V.90.

Most PCI and PC Card sold since mid-2001.

PROTOCOLS


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MODEMMODEMMODEM NEGOTIATION


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MODEMMODEM

Dialing state: a ring input causes a transition to the ringing state,

while a busyinput causes a transition back to the idle state.

Note: In a better modem design, the modem would set a timer and attempt to

dial again after some time had expired.Answer toneis detected, state machine transitions to the modem

detected state because it has now been determined that there is amodem at the other end of the telephone line. In case there is no modem at the other end of the line, a timer is set which

produces a timout event after 15 seconds, causing the modem to transition

back to the idle state. In the modem detectedstate, the modem emits a signal that

identifies its highest possible connection speed. e.g. 33 kbps (kilobits per second). If the modem at the other end is capable of

operating at this speed, it will respond with a signal that is seen by the modemas an id1 response input.

MODEM NEGOTIATION


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MODEMMODEM

If instead the timer expires, then the modem at the other endmust not be capable of operating at 33 kbps, so the modememits a different signal identifying a lower speed that it is

capable of operating at, say 14.4 kbps.When the far-end modem responds to any of the id signals,then the near end modem emits a training sequence.

Training sequence which is a pre-agreed signal that permits themodem at the far end to measure the impairments on thetelephone channel and set up adaptive filters to compensate for

these impairments. Then the modem at the far end responds bysending back a training sequence, which allows the near-endmodem to set up its adaptive filters.

MODEM NEGOTIATION


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MODEMMODEM

After both modems have set up their filters, a convergedevent causes the modem to transition to the connectedstate, in which data communication occurs. You can now

start surfing the web.Note: A better design would use a timeout timer sothat if convergence does not occur, the modem triesto connect at a lower speed.

MODEM NEGOTIATION

Modem Fails to Dial


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MODEMMODEM

Modem Fails to Dial

1. Check line and phone jacks on the modem. Use the line jack to attach themodem to the telephone line. The phone jack takes the same RJ-11 silver cordcable, but its designed to let you daisy-chain a telephone to your modem, soyou need only a single line for modem and telephone use. If you have reversedthese cables, you will not get a dial tone.

2. If the cables are attached properly, check the cable for cuts or breaks. Theouter jacket used on RJ-11 telephone cables is minimal. If the cable looks bad,replace it.

3. If the modem is external, make sure the RS-232 modem cable is running fromthe modem to a working serial port on your computer and that is switched on.

Signal lights on the front of the modem can be used to determine whether themodem is on and whether it is responding to dialing commands.

PROBLEMS & TROUBLESHOOTING

Modem Fails to Dial


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MODEMMODEM

4. If the modem is a PC Card (PCMCIA card). Make sure it is fully plugged into the PCMCIA/PCslot. With Windows 9x/Me/2000/XP, you should see a small PCMCIA/PC Card icon on thetoolbar. Double click it to view the cards that are currently connected. If your modem isproperly attached, it should be visible. Otherwise, remove it, reinsert it into the PCMCIA/PCCard slot, and see whether the computer detects it.

5. Make sure your modem has been properly configured by your OS. With Windows9x/Me/2000, use the Modems control panel to view and test your modem configuration (withWindows XP, you can use the Modem Troubleshooter). Select your modem and click thediagnostics tab. This displays the COM (serial) ports in your computer. Select the COM portused by the modem, and click the More Info tab. This sends test signals to your modem. Aproperly working modem responds with information about the port and modem.


Modem Fails to Dial


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MODEMMODEM

Modem Fails to Dial

6. If you get a Couldnt Open Port error message, your modemisnt connected properly. It might be in use already by aprogram running in the background, or there might be an IRGor I/O port address conflict with another card in yourcomputer. Whether you have a modem installed, every COMport that is working will display its IRQ, I/O port address andUART chip type when you run Diagnostics. The UART typeshould be 16550 or above for use with any modern modem.



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MODEMMODEM

Computer Cant Detect External Modem

1. Make sure the modem has been connected to the computerwith the correct type of cable.

2. Make sure the COM (serial) port or USB port to which themodem is connected to is working.

3. Check the power cord and power switch.



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MODEMMODEM

Using Your Modem Sound to Diagnose Your Modem

1. If you listen to your modem when it makes a connection, you might

have realized that different types of modems make distinctiveconnection sounds and that different connection speeds also makedistinctive sounds.

2. The various types of 56Kbps modems have distinctly differenthandshakes of tones, buzzes and warbles as they negotiate speeds withthe ISPs modem.

3. Check out www.modemsite.com/56k/trouble.asp (click handshake link)for find out sound samples of various modems during the handshakingprocess for troubleshooting.

http://www.modemsite.com/56k/trouble.asphttp://www.modemsite.com/56k/trouble.asp


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ENDEND

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