Section 8.


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Description
Plan. CircuitMode of transmissionDigital transmissionAnalog transmission for computerized signals - modemsMethodsClassificationInterfacesFunctionsSelection Criteria. Circuit. Signal rateNo. of sign changes (plentifulness, recurrence, or stage) on a circuit for each secondBaudTypes: dibits, tribits, and quadbitsSpeedNo. of bits that a circuit can convey in 1 secondBits every second (bps) utilized for estimation.
Transcripts
Slide 1

Section 8 Data Transmission and Modems

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Agenda Circuit Mode of transmission Digital transmission Analog transmission for computerized signals - modems Methods Classification Interfaces Functions Selection Criteria

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Circuit Signal rate No. of flag changes (sufficiency, recurrence, or stage) on a circuit for every second Baud Types: dibits, tribits, and quadbits Speed No. of bits that a circuit can convey in 1 second Bits for each second (bps) utilized for estimation

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Mode of Transmission Data stream Physical association Timing

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Data Flow - US Simplex transmission Television and radio Half-duplex (HDX) transmission CB radio, terminal Full-duplex (FDX) transmission Telephone, PC to PC

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Physical Connection Parallel transmission Fast Simple Line cost Serial transmission Complicated transmitter and get Decomposing and reproducing

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Timing Asynchronous transmission Start/stop bits for character synchronization Mark (1or stop)/space (0 or begin ) bits for bit synchronization Simple, modest, moderate speed transmission For PC Synchronous transmission Clock hardware One to four synchronization characters for every piece of information Large measure of information on committed line

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Digital Signals Unipolar (positive voltage for 1, no voltage for 0) Bipolar, nonreturn-to zero (NRZ) Manchester coding (low-to-high is 1, high-to-low is 0) Differential Manchester (no move toward the start of the bit time frame is 1, second move toward the start of the bit time frame is 0) Benefits: self-timing, and blunder location Bipolar, come back to-zero

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Benefits of Digital Transmission Better information respectability (recognize & rectify mistake) Higher limit links (fiber-optic) Easier incorporation (voice, information, video, and so forth.) Better security and security (scramble information) Lower cost (expansive scale coordinated hardware)

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Digital Transmission of Analog Signals Quantization Quantizing clamor or digitizing bending Codec (coder/decoder): simple to-computerized (A/D) converter & advanced to-simple (D/A) converter Methods Pulse code regulation (256 whole numbers, 8000 every second) Adaptive differential heartbeat code tweak (contrast) Delta balance (1 for +, 0 for - )

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Digital Transmission of Digital Signals Digital transmitter/beneficiary (information benefit unit/station benefit unit (DSU/CSU)) Simpler & less expensive Transmitter for molding & timing the flag, interface amongst DTE and line Receiver for assurance of inordinate voltage, demonstrative and testing

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Analog Transmission of Digital signs (Modems – I) Modulation and Demodulation Receiver (balance), control unit (auto dial & auto reply), transmitter (demodulation), & control supply Equalizer in transmitter & versatile equalizer in recipient (change in accordance with fit the attributes of the phone line) Methods Frequency move keying (FSK) Phase move keying (PSK): 180 degree (1 bit), 90 degree (2 bits), 45 degree (3 bits) Differential stage move keying (DPSK) Quadrature sufficiency balance (QAM): blend of 8 stages & 4 relative amplitudes

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Modems - II Methods Trellis code balance: flag processor, mistake amendment for blunder free transmission, rapid Standards by ITU-T V.32 for 9.6 kbps & V.32bis for 14.4 kbps V.34 for 28.8 kbps & V.34+ or V.34bis for 33.6 kbps V.90 for 56 kbps

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Modems - III Handshaking Exchange motions between modems Test the qualities of circuit and quality decide baud rate, adjustment procedure and mistake control Data pressure V.42bis by ITU-T Microcom Networking Protocol (MNP 7 or 10) by Microcom, Inc.

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Modem Classification Simplex, half-duplex, full-duplex transmission modems Asynchronous or synchronous transmission modems Acoustically coupled modems (convenient) Limited separation modems/short pull modems (under 20 miles) Modem eliminators/invalid modems (link not exactly a few thousand feet)

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Modem Classification - II Facsimile modems Error revision and information pressure Modem for fiber-optics circuits Digital-electrical to advanced optical Cable modems DTE to satellite TV framework link Data Over Cable Service Interface Specification (DOCSIS) by CableLabs For extensive records and not logon prepare

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Modem Classification - III Reverse station Slow speed switch station for flagging each other Auto dial/auto answer Hayes Microcomputer Product, Inc. Charge AT for consideration Internet benefit supplier use Dial-reinforcement open phone arrange association for rented phone line Internal modem Single circuit card No change to change the parameters and operations

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Modem Interfaces Between modem and line Between DTE and modem

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Between Modem and Line Two-to four-wire link RJ-11 plug

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Between Modem and DTE RS-232-C interface V.24 interface RS-232-D interface RS-449 interface RS-336 interface X.21 interface X.21bis interface Current circle interface

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RS-232-C Interface By EIA and ITU-T V.24 Characteristics 25-stick connector at both end computerized and serial Female for DCE and male for DTE Pins 2 and 3 to pass information, other for flagging Limitations 50 - 100 feet link length 2,400 - 9,600 bps Hard to contrast 0 and 1 when speed is high and link is long

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RS-232-D Interface Specifications for the 25-stick connector Addition of a shield on the link Redefinition of defensive ground and a few pins

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RS-449 Interface 37 pins 4,000 feet link Not all around acknowledged

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RS-336 Interface Automatic dialing from PC to remote terminals for information gathering Not for rapid transmission

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X. Interfaces X.21 interface Digital association with a computerized open phone organize X.21bis interface Terminal to parcel switch arrange by means of simple line

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Current Loop Interface Represent 1 and 0 by nearness or nonappearance of an electrical current Simple and modest Nonstandard Teletywriter framework

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Other Modem Functions Reverse station for flag each other to decide the speed Auto dial/auto answer Modem diagnostics Loop back for precision checking

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Modem Selection Criteria Digital or simple signs Asynchronous or synchronous Speed Distance Type of line Cost Functions

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Spread Spectrum Analog flag for simple or advanced information Frequency jumping promotion coordinate succession Generated by Pseudo arbitrary number generator

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Points to Remember Circuit Mode of transmission Digital transmission Analog transmission for advanced signs - modems Methods Classification Interfaces Functions Selection Criteria

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Discussion Design the information transmission and modem determination for a bank

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